Header Graphic
Apps for iPad

FAA Glossaries

Touring Machine Company

Chasing the Needles

May 9th, 2017

One of the reasons pilots often chase the needles on an ILS approach is that they don’t have a clear understanding of how the sweet spot narrows as they approach the runway.

From the Pilot and Air Traffic Controller Guide to Wake Turbulence

Glideslope Deviation
Glideslope Deviation

Localizer Deviation
Localizer Deviation

The Outer Marker, which normally identifies the final approach fix (FAF), is four to seven nautical miles before the runway threshold.

I don’t have a chart for the VOR, but is is similar, just not as sensitive
At 30 NM each dot is approximately 1 NM displacement.
At 15 NM each dot is approximately 1/2 NM displacement.

So when you are tracking a VOR to the airport, at the FAF you are usually about 6 nm from the runway threshold. If the VOR is on the field, then each dot is about 1/5 NM (1,200′) displacement.

Designated Mountainous Areas

May 7th, 2017

Flying on the West Coast, I am used to just about everywhere being considered mountainous except for portions of California’s Central Valley. I had a picture of the map in my mind, but couldn’t remember where I had seen it.

Designated Mountainous Areas

After a little digging, I found two sources:

CFR §95 Subpart B—Designated Mountainous Areas has a map that you can download.

The AIM 5−6−5. ADIZ Boundaries and Designated Mountainous Areas also has a map.

The MEA and MOCA on airways in mountainous areas provide 2,000′ of obstacle clearance while in non-mountainous areas they only provide 1,000′.

How a magneto works.

May 6th, 2017

If you ever wondered how a magneto works, you can stop wondering.

There is no requirement to have the magnetos refurbished, but I always do when they have around 500 hours on them. It is fairly expensive, around $500 each depending on which parts need to be replaced. But is is much cheaper than new or overhauled mags.

Here’s an old video explaining how magneto’s work. A little bit boring, but good stuff.

We do a timing check like this at every annual.

And here are some goofy A&P students running through the whole process.

And while we are on the subject of magnetos, it is important to do a check to make sure both the switch and the leads are grounding. There is an AD on my Bendix switch that requires this every 100 hours. It can be done and logged by the pilot, so I do it every month when I do my monthly maintenance checks.

Wobbly Tire

May 3rd, 2017

On takeoff last week, I noticed a lot of shimmy so I aborted the takeoff. We put the plane on jacks and it looked like this.

What altitude to fly on a STAR when it reads “expect”?

May 1st, 2017

I just took the instrument knowledge test and one of the questions referred to this STAR. I got this question right, but for the wrong reason.

STELLA.ONE Arrival

The question stated that you were cleared for the STELA ONE arrival from the west and asked what altitude you should be at when crossing STELA. My understanding of a clearance for a STAR was that, unless otherwise instructed, you should use both the lateral and vertical guidance on the chart. So at STELA, you should be at 11000′. The notation for expect isn’t applicable unless you were told to fly at a higher altitude when given your clearance. Even then, you wouldn’t descend to 11000′ until instructed.

However, I was mistaken. Unlike departure procedures and approach procedures, a STAR only provides lateral and airspeed guidance unless an alitude is specified with underlines or overlines.

AIM 5−4−1. Standard Terminal Arrival (STAR) Procedures
a. A STAR is an ATC coded IFR arrival route established for application to arriving IFR aircraft destined for certain airports. STARs simplify clearance delivery procedures, and also facilitate transition between en route and instrument approach procedures.

1. STAR procedures may have mandatory speeds and/or crossing altitudes published. Other STARs may have planning information depicted to inform pilots what clearances or restrictions to “expect.” “Expect” altitudes/speeds are not considered STAR procedures crossing restrictions unless verbally issued by ATC. Published speed restrictions are independent of altitude restrictions and are mandatory unless modified by ATC. Pilots should plan to cross waypoints with a published speed restriction, at the published speed, and should not exceed this speed past the associated waypoint unless authorized by ATC or a published note to do so.

NOTE−
The “expect” altitudes/speeds are published so that pilots may have the information for planning purposes. These altitudes/speeds must not be used in the event of lost communications unless ATC has specifically advised the pilot to expect these altitudes/speeds as part of a further clearance.

Pilots navigating on STAR procedures must maintain last assigned altitude until receiving authorization to descend so as to comply with all published/issued restrictions. This authorization may contain the phraseology “DESCEND VIA.” If vectored or cleared to deviate off of a STAR, pilots must consider the STAR canceled, unless the controller adds “expect to resume STAR;” pilots should then be prepared to rejoin the STAR at a subsequent fix or procedure leg. If a descent clearance has been received that included a crossing restriction, pilots should expect the controller to issue an altitude to maintain.

  (a) Clearance to “descend via” authorizes pilots to:
  (1) Descend at pilot’s discretion to meet published restrictions and laterally navigate on a STAR.
  (2) When cleared to a waypoint depicted on a STAR, to descend from a previously assigned altitude at pilot’s discretion to the altitude depicted at that waypoint.
  (3) Once established on the depicted arrival, to descend and to meet all published or assigned altitude and/or speed restrictions.

In the case of the exam question, the instruction did not include the phrase “Descend via” and so the altitude to cross STELA would be whatever altitude the pilot was last cleared to, which to the best of my recollection, was not one of the answers.

Good explanation on Bold Method.

Night Flying

April 30th, 2017

Here’s an old FAA film about night flying. The film does a good job of covering the risks and rewards of night flight. Except for the outdated “Over” at the end of each transmission and the presence of Flight Service Stations on the airport, everything they say still applies.

Things to Remember IRA Knowledge Test

April 16th, 2017

Instruments

Alternate static source:
Altimeter higher, Airspeed greater than actual, Momentary rise in VSI

Altimeter
High to low, look out below. Applies to pressure and temperature.
Altitude goes in the same direction as the pressure setting in the Kollsman window.
e.g 1″ decrease for each 1000′ decrease in altitude, 1″ increase for each 1000′ increase in altitude.
In colder than standard air temperature true altitude will be lower than indicated altitude with an altimeter setting of 29.92 inches Hg.

Inclinometer
In a turn made with a bank angle that is too steep, the force of gravity is greater than the inertia and the ball rolls down to the inside of the turn (slip). If the turn is made with too shallow a bank angle, the inertia is greater than gravity and the ball rolls upward to the outside of the turn (skid).

Return to coordinated flight from a skid, increase the bank angle and/or reduce the rate of turn with rudder.
Return to coordinated flight from a slip, decrease the bank angle and/or increase the rate of turn with rudder.

Airspeed
As altitude increases Vx increases.
As altitude increases Vy decreases.

Attitude indicator
There may be a slight nose-up indication during a rapid acceleration and a nose-down indication during a rapid deceleration. There is also a possibility of a small bank angle and pitch error after a 180° turn.

Directional gyro
Check, in straight and level flight, about every 15 minutes or after holding pattern.

Turn Coordinator
First shows the rate of bank, and once established, the rate of turn.

VOR
At 30 NM each dot is appoximately 1 NM displacement.
So 1 NM is ~200′.
Minutes to station = Time (seconds)/Bearing Change (degrees)
then Distance to station = True Airspeed (kts) * Time (seconds)

VOT
With the CDI centered, the OBS should read 0° showing FROM or 180° showing TO.
RMI indicates 180° TO on any OBS setting.

HSI
The slaving meter indicates the difference between the displayed heading and the magnetic heading. A right deflection indicates a clockwise error of the compass card; a left deflection indicates a counterclockwise error.

Fundamental Skills of Instrument Flying
Cross-check, Interpretation, Control

Unusual Attitude—Nose High
Add power, Reduce Pitch, Level the Wings – Leveling the wings first may result in a spin.

Unusual Attitude—Nose Low
Reduce power, Level the Wings, Increase Pitch – Increasing the pitch first will increase the bank and may overstress the airframe.

Wake Turbulence
Wingtip vortices are greatest when the generating aircraft is “heavy, clean, and slow.” This condition is most commonly encountered during approaches or departures because an aircraft’s AOA is at the highest to produce the lift necessary to land or take off.

Approach the runway above a preceding aircraft’s path when landing behind another aircraft and touch down after the point at which the other aircraft wheels contacted the runway.

Close to the ground (within 100 to 200 feet), they tend to move laterally over the ground at a speed of 2 or 3 knots. A wind speed of 10 knots causes the vortices to drift at about 1,000 feet in a minute in the wind direction.

Clear Air Turbulence
Moderate CAT is considered likely when the vertical wind shear is 5 kts per 1,000 feet or greater, and/or the horizontal wind shear is 40 kts per 150 miles or greater.

Jet streams stronger than 110 kts (at the core) have potential for generating significant turbulence near the sloping tropopause above the core, in the jet stream front below the core, and on the low-pressure side of the core.

Wind Shear
Directional wind changes of 180° and speed changes of 50 knots or more are associated with low-level wind shear. Low-level wind shear is commonly associated with passing frontal systems, thunderstorms, and temperature inversions with strong upper level winds (greater than 25 knots).

With a warm front, the most critical period is before the front passes.

When a constant tailwind shears to a calm or headwind, the plane’s airspeed increases causing the the nose to pitch up, and it has a tendency to go above the glide slope.

When a constant headwind shears to a calm or tailwind, the plane’s airspeed decreases causing the the nose to pitch down, vertical speed increases, and it has a tendency to go below the glide slope.

Microburst
Microburst activity may be indicated by an intense rain shaft at the surface but virga at cloud base and a ring of blowing dust is often the only visible clue. A typical microburst has a horizontal diameter of 1–2 miles and a nominal depth of 1,000 feet. The lifespan of a microburst is about 5–15 minutes during which time it can produce downdrafts of up to 6,000 feet per minute (fpm) and headwind losses of 30–90 knots,

Airport Markings

Threshold -> Touchdown Markings 500′
Threshold -> Aiming Point 1,000′
Threshold Markings -> 4 Stripes: 60′ to 16 Stripes: 200′
Centerline Stripe
Centerline lights are white until the last 3,000 feet of the runway. The white lights begin to alternate with red for the next 2,000 feet, and for the last 1,000 feet of the runway, all centerline lights are red.
Precision Runways have Touchdown Zone and Side Stripe

VASI provides obstacle clearance 4nm from threshold and 10° laterally.

Touchdown zone elevation (TDZE). The highest elevation in the first 3,000 feet of the landing surface, TDZE is indicated on the instrument approach procedure chart when straight-in landing minimums are authorized.

Approach
Parallel ILS approaches provide aircraft a minimum of 1 1/2 miles radar separation between successive aircraft on the adjacent localizer course.

When the approach procedure involves a procedure turn, the maximum speed should not be greater than 200 kts.

The Glide Path Qualification Surface (GQS) limits the height of obstructions between the decision altitude and the runway threshold.

Stabilized approach: Straight in before FAF and before descending below 1,000′ AGL, Visual or circling before 500′ AGL
Engines spooled up, Descent less than 1,000 fpm, bank angle less than 15°

Approach Category
Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3 VSO at the maximum certified landing weight.


    Category A: Speed less than 91 knots.                          1.3 NM Protected Area
    Category B: Speed 91 knots or more but less than 121 knots.    1.5 NM
    Category C: Speed 121 knots or more but less than 141 knots.   1.7 NM
    Category D: Speed 141 knots or more but less than 166 knots.   2.3 NM
    Category E: Speed 166 knots or more.                           4.5 NM 

Expanded circling area (after 2012) varies by MSL.

Missed Approach
Missed approach obstacle clearance is assured only if the missed approach is commenced at the published MAP. Before initiating an IAP that contains a “Fly Visual to Airport” segment, the pilot should have preplanned climb out options based on aircraft performance and terrain features. Obstacle clearance is the responsibility of the pilot when the approach is continued beyond the MAP.

Holding


     Altitude (MSL)    Airspeed (KIAS)    Leg Time
     MHA - 6,000'           200           1 minute
     6,001' - 14,000’       230           1 minute 30 seconds
     14,001' and above      265           1 minute 30 seconds

Most GA aircraft use approach airspeed.

The pilot should begin outbound timing over or abeam the fix, whichever occurs later. If the abeam position cannot be determined, start timing when the turn to outbound is completed (wings level).

En Route
When ATC has not imposed any climb or descent restrictions and aircraft are within 1,000 feet of assigned altitude, pilots should attempt to both climb and descend at a rate of between 500 and 1,500′.

Hyperventilation
Breathing normally is both the best prevention and the best cure for hyperventilation. In addition to slowing the breathing rate, breathing into a paper bag or talking aloud helps to overcome hyperventilation.

Hypoxia
The reactions of the average person become impaired at an altitude of about 10,000 feet, but for some people impairment can occur at an altitude as low as 5,000 feet. The physiological reactions to hypoxia or oxygen deprivation are insidious and affect people in different ways. These symptoms range from mild disorientation to total incapacitation, depending on body tolerance and altitude.

Hypoxic hypoxia is a result of insufficient oxygen available to the body as a whole.
High altitude. CO2 in cabin from dry ice.

Hypemic hypoxia occurs when the blood is not able to take up and transport a sufficient amount of oxygen to the cells in the body.
CO poisoning, Blood donation. Bleeding. Smoking. Also called anemic hypoxia on the tests.

Stagnant hypoxia or ischemia results when the oxygen-rich blood in the lungs is not moving, for one reason or another, to the tissues.
Heart attack. Excessive acceleration of gravity (Gs). Cold temperatures can also reduce circulation and decrease the blood supplied to extremities.

Histotoxic hypoxia is the inability of the cells to effectively use oxygen.
Alcohol and other drugs, such as narcotics and poisons

Weather
Unstable Air
Moist, unstable air causes cumulus clouds, showers, and turbulence to form.
Unstable air masses usually have good surface visibility.

Unstable air: Cumuliform clouds, Showery precipitation, Rough air (turbulence), Good Visibility.

Stable Air
A stable air mass can produce low stratus clouds and fog.
Stable air masses usually have poor surface visibility. The poor surface visibility is due to the fact that smoke, dust, and other particles cannot rise out of the air mass and are instead trapped near the surface.

Stable air; Stratiform clouds and fog, Continuous precipitation, Smooth air, Fair to poor visibility in haze and smoke.

Lapse Rates
Rising dry air cools at a lapse rate of 3°C per 1000′ (5.4°F). The dewpoint decreased .5°C (1°F) per 1000′.
Temperature and dew point converge at 2.5°C (4.4°F).
Moist adiabatic lapse rate, which varies between approximately 1.2°C per 1,000 feet for very warm saturated parcels to 3°C per 1,000 feet for very cold saturated parcels.
Average lapse rate is 2°C per 1,000′.

Squall
A sudden increase in wind speed by at least 15 knots to a peak of 20 knots or more and lasting for at least one minute. Essential difference between a gust and a squall is the duration of the peak speed. Wind speed variation of 10kts between peaks and lulls.

A squall line is a non-frontal, narrow band of active thunderstorms. Often it develops ahead of a cold front in moist, unstable air, but it may develop in unstable air far removed from any front. The line may be too long to easily detour and too wide and severe to penetrate. It often contains severe steady-state thunderstorms and presents the single most intense weather hazard to aircraft.

An airplane is most likely to be struck by lightning when the OAT is between -5°C and +5°C.

Icing
Freezing Drizzle— precipitation at ground level or aloft in the form of liquid water drops that have diameters less than 0.5 mm and greater than 0.05 mm. In freezing drizzle, the pilot cannot assume that a warm layer exists above the aircraft.
Freezing Rain—precipitation at ground level or aloft in the form of liquid water drops which have diameters greater than 0.5 mm. Freezing rain will result in ice forming in areas far aft of where it would normally form in icing conditions without freezing rain.
Supercooled Large Drops (SLD). Water drops with a diameter greater than 50 micrometers (0.05 mm) that exist in a liquid form at air temperatures below 0 °C.

Supercooled Clouds—Nearly all aircraft icing occurs in supercooled clouds. Liquid drops are present at outside air temperatures (OAT) below 0 °C (32°F) in these clouds. At temperatures below about -20°C (-4°F), most clouds are made up entirely of ice particles.

SLD may result in drops impinging aft of protected surfaces and causing ice accumulation behind the protected area of leading edges. These surfaces may be very effective ice collectors, and ice accumulations may persist as long as the aircraft remains in icing conditions.

Cloud water drops are generally very small, averaging 20 micrometers (.02 mm) in diameter, and are of such small mass that they can be held aloft by small air currents within clouds. If the temperatures are cold enough at the tops (below or around -15 °C (5 °F), ice particles will usually start to form that tend to deplete the liquid water.

Reporting Icing
Trace Icing—Ice becomes noticeable. The rate of accumulation is slightly greater than the rate of sublimation.
Light Icing—The rate of ice accumulation may create a problem if flight is prolonged in this environment (over 1 hour). Requires occasional cycling of manual deicing systems. 1⁄4 inch to 1 inch (0.6 to 2.5 cm) per hour on the outer wing.
Moderate Icing—Requires frequent cycling of manual deicing systems Anything more than a short encounter is potentially hazardous. 1 to 3 inches (2.5 to 7.5 cm) per hour on the outer wing.
Severe Icing—Ice protection systems fail to remove the accumulation of ice and accumulation occurs in areas not normally prone to icing. More than 3 inches (7.5 cm) per hour on the outer wing.

Clear Ice—Temperatures close to the freezing point, large amounts of liquid water, high aircraft velocities, and large drops are conducive to the formation of clear ice.
Rime Ice—Low temperatures, lesser amounts of liquid water, low velocities, and small drops favor formation of rime ice.

Carburetor Icing—May occur at temperatures between 20°F (-7°C) and 70°F (21°C).

Deicing
Boots—The amount of ice increases as airspeed or temperature decreases. The FAA recommends that the deicing system be activated at the first indication of icing.

Ice protection systems on airplanes certificated prior to 1973 should be considered a means to help exit icing conditions.

For small amounts of ice accretion, effects not apparent while operating in the middle of the flight envelope may be noticeable when operating at the edge of the flight envelope. The most common are an increase in stall speed (with a late or no warning) or the inability to climb at altitude.

Roll Upsets
Ice on the wings forward of the ailerons can affect roll control. The tips are usually thinner than the rest of the wing, and so they most efficiently collect ice. This can lead to a partial stall of the wings at the tips, which can affect the ailerons and thus roll control.

• Reduce the AOA by reducing the aircraft pitch. Roll the wings level.
• Set the appropriate power and monitor the airspeed and AOA.
• If the flaps are extended, do not retract them unless it can be determined that the upper surface of the airfoil is clear of ice. Retracting the flaps will increase the AOA at a given airspeed.
• Verify that the wing ice protection is functioning normally.

Tailplane Stall
An ice-contaminated tailplane stall typically occurs either while extending the wing trailing edge flaps to the landing position; with the flaps already extended to that position; or with the flaps already extended to that position when operating in, or departing from, icing conditions. Since flaps are normally only extended to the landing piosition during final approach to landing, tailplane stalls as the result of ice accumulation are most common in this phase of flight.

Elevator control pulsing, oscillations, or vibrations as well as any other unusual or abnormal pitch anomalies (possibly resulting in pilot-induced oscillations) are indicative of tailplane ice accumulation and the potential for a tailplane stall. You should retract the flaps to the last safe setting in this situation.

Blocked Pitot/Static System Effects
If the pitot tube inlet becomes blocked, air already in the system will vent through the drain hole, and the remaining will drop to ambient (i.e., outside) pressure. Airspeed indicator decreases to zero.

If the pitot tube, drain hole, and static system all become blocked in flight changes in airspeed will not be indicated, due to the trapped pressures.

If the static system remains clear, the airspeed indicator would display a higher­ than-actual airspeed as the altitude increased. As altitude is decreased, the airspeed indicator would display a lower-than-actual airspeed.

If the static port becomes blocked, the airspeed indicator would still function; however, it would be inaccurate. At altitudes above where the static port became blocked, the airspeed indicator would indicate a lower-than-actual airspeed. At lower altitudes, the airspeed indicator would display a higher-than-actual airspeed.

The trapped air in the static system would cause the altimeter to remain at the altitude where the blockage occurred.

If an alternate source is vented inside the airplane, where static pressure is usually lower than outside static pressure, selection of the alternate source may result in the following erroneous instrument indications: The altimeter reads higher than normal, the indicated airspeed reads greater than normal, the vertical speed indicator momentarily shows a climb.

Icing conditions in stratiform clouds often are confined to a relatively thin layer, either climbing or descending may be effective in exiting the icing conditions within the clouds. Icing encountered in cumulus clouds may be of limited duration; it may be possible to deviate around the cloud.

Weather Products
ATIS
Absence of the sky condition and visibility on an ATIS broadcast specifically implies that the ceiling is more than 5,000 feet and visibility is 5 miles or more.

TAF
The body of a Terminal Aerodrome Forecast (TAF) covers a geographical proximity within a 5 statute mile radius from the center of an airport runway complex.

Area Forecast (FA)
It was replaced by Graphic Area Forecasts (GFA) in 2017.

“WND” is appended to any category if the sustained surface wind is expected to be 20 kts or more, or surface wind gusts are expected to be 25 kts or more during the majority of the 6-hour outlook period.

The VFR CLDS/WX section describes conditions consisting of MVFR cloud ceilings (1,000 to 3,000 feet AGL), MVFR obstructions to visibility (3-5 statute miles), and any other significant VFR clouds (bases at or below FL180) or VFR precipitation.

Wind and Temperature Aloft Forecast (FB)
The symbolic form of the forecasts is DDff+TT in which DD is the wind direction, ff the wind speed, and TT the temperature. Wind direction is indicated in tens of degrees (two digits) with reference to true north and wind speed is given in knots (two digits). Light and variable wind or wind speeds of less than 5 knots are expressed by 9900. Forecast wind speeds of 100 through 199 knots are indicated by adding 100 to the speed and subtracting 50 from the coded direction.
No winds forecast within 1,500′ of station elevation. No temp within 2,500′ of reporting and 3,000′ level.
Temps are negative above 24,000′

Weather Depiction Chart
The Weather Depiction Chart is being phased out by the NWS, in favor of newer ceiling and visibility products, like the CVA product.

Weather Advisory
A warning of hazardous weather conditions not predicted in the forecast area that may affect air traffic operations.

AIRMET, SIGMET
An AIRMET is a weather advisory issued only to amend the area forecast concerning weather phenomena which are of operational interest to all aircraft and potentially hazardous to aircraft having limited capability because of lack of equipment, instrumentation, or pilot qualifications. A SIGMET is a weather advisory issued concerning weather significant to the safety of all aircraft.

AIRMETs and SIGMETs are considered to be widespread because they must be affecting or be forecast to affect an area of at least 3000 square miles at any one time.

AIRMET
Sierra—Instrument Flight Rules (IFR) or Mountain Obscuration—Ceilings less than 1000 feet and/or visibility less than 3 miles affecting over 50% of the area at one time. Extensive mountain obscuration
Tango—Turbulence, Moderate Turbulence, Sustained surface winds of greater than 30 knots at the surface
Zulu—Icing, Moderate icing, Freezing levels
Routinely issued for 6 hour periods.

SIGMET—Severe Icing, Severe or Extreme Turbulence, Dust storms and/or sand storms lowering visibilities to less than three (3) miles, Volcanic Ash. Issued for 6 hour periods for conditions associated with hurricanes and 4 hours for all other events.

Convective SIGMETs—Severe surface weather including: surface winds greater than or equal to 50 knots, hail at the surface greater than or equal to 3/4 inches in diameter, tornadoes, embedded thunderstorms, line of thunderstorms, thunderstorms greater than or equal to VIP level 4 affecting 40% or more of an area at least 3000 square miles. Valid for up to 2 hours.

CWAs are advisories issued by the Center Weather Service Units (CWSUs) that are for conditions just below severe criteria. CWAs are issued for: Thunderstorms, Turbulence, Icing, Ceiling & Visibility (IFR)

Vestibular Illusions
The Leans
When a banked attitude, to the left for example, may be entered too slowly to set in motion the fluid in the “roll” semicircular tubes. An abrupt correction of this attitude sets the fluid in motion, creating the illusion of a banked attitude to the right.

Coriolis Illusion
The coriolis illusion occurs when a pilot has been in a turn long enough for the fluid in the ear canal to move at the same speed as the canal. A movement of the head in a different plane, such as looking at something in a different part of the flight deck, may set the fluid moving and create the illusion of turning or accelerating on an entirely different axis.

Graveyard Spiral
A pilot in a prolonged coordinated, constant-rate turn, will have the illusion of not turning. During the recovery to level flight, the pilot experiences the sensation of turning in the opposite direction.

Somatogravic Illusion
A rapid acceleration, such as experienced during takeoff, stimulates the otolith organs in the same way as tilting the head backwards. This action creates the somatogravic illusion of being in a nose-up attitude.

Inversion Illusion
An abrupt change from climb to straight-and-level flight can stimulate the otolith organs enough to create the illusion of tumbling backwards or inversion illusion.

Elevator Illusion
An abrupt upward vertical acceleration, as can occur in an updraft, can stimulate the otolith organs to create the illusion of being in a climb.

Turning Illusions
Without visual aid, a pilot often interprets centrifugal force as a sensation of rising or falling.
While in the turn, without outside visual references and under the effect of the slight positive G, the usual illusion produced is that of a climb. On recovery from the turn, at approximately one-half completed the usual illusion will be that the aircraft is diving.

Visual Illusions
False Horizon
A sloping cloud formation, an obscured horizon, an aurora borealis, a dark scene spread with ground lights and stars, and certain geometric patterns of ground lights can provide inaccurate visual information, or false horizon, for aligning the aircraft correctly with the actual horizon.

Autokinesis
In the dark, a stationary light will appear to move about when stared at for many seconds.

Optical Illusions
Runway and Terrain Slopes Illusion
A narrower-than-usual or an upsloping runway, upsloping terrain can create an illusion the aircraft is at a higher altitude than it actually is.

Featureless Terrain Illusion
An absence of surrounding ground features, as in an overwater approach, over darkened areas, or terrain made featureless by snow, can create an illusion the aircraft is at a higher altitude than it actually is.

Water Refraction
Rain on the windscreen can create an illusion of being at a higher altitude due to the horizon appearing lower than it is.

Haze
Atmospheric haze can create an illusion of being at a greater distance and height from the runway.

Fog
Flying into fog can create an illusion of pitching up.

Ground Lighting Illusions
Lights along a straight path, such as a road or lights on moving trains, can be mistaken for runway and approach lights.

ATC Reports
Reports

Reports that should be made without a specific request from ATC
• VFR-on-top change in altitude
• Missed approach
• Leaving one assigned flight altitude for another
• Leaving any assigned holding fix or point
• Unable to climb or descend at least 500 feet per minute
• TAS variation from filed speed of 5% or 10 knots, whichever is greater
• Time and altitude upon reaching a holding fix
• Loss of NAV/Comm capability
• Unforecasted weather conditions or other information relating to the safety of flight

Readback of airborne clearance
Q:What response is expected when ATC issues an IFR clearance to pilots of airborne aircraft?
A: Read back those parts containing altitude assignments or vectors and any part requiring verification.

Non RADAR Reports
If radar contact has been lost the CFRs require pilots to provide ATC with position reports over designated VORs
• Compulsory reporting points as depicted on IFR en route charts by solid triangles
• Leaving FAF or OM inbound on final approach
• Revised ETA of more than three minutes

Miscellaneous Things I Can’t Remember
An abbreviated departure clearance, …Cleared as Filed…, will always contain the destination airport (or clearance limit), en route altitude, advise to expect an assigned altitude or filed altitude at a certain point after departure. It also includes the Departure Procedure if appropriate.

To level off at an airspeed higher than the descent speed, the addition of power should be made, assuming a 500 FPM rate of descent, at approximately 100 to 150 feet above the desired altitude.

If severe turbulence is encountered during your IFR flight, the airplane should be slowed to the design maneuvering speed because the amount of excess load that can be imposed on the wing will be decreased.

Types of NOTAMs.
FDC NOTAMs Advise of changes in flight data which affect instrument approach procedure (IAP), aeronautical charts, and flight restrictions prior to normal publication.
NOTAM (D) Consists of information that requires wide dissemination via telecommunication and pertains to: En Route navigational aids, Civil public-use airports listed in the Airport Facility Directory (AFD), Facilities Services
NOTAM (L) information pertinent to the departure and/or local area—Discontinued except for military.

ATC may request a detailed report of an emergency even though a rule has not been violated when priority has been given.

DME Arc

April 13th, 2017

Both the Gleim and the ASA Knowledge Test Study Guides give a formula for for calculating the distance travelled along a DME arc that just didn’t look right to me.

The formula is (# of degrees x DME arc) ÷ 60. But the true formula should be based on the percentage of the circle that the airplane travels.

The formula for the circumference of a circle (the distance around it) is 2πr where r is the radius of the circle (DME arc in their notation). So the distance travelled should be the percentage of the circle. The formula is (2π x DME arc) x (# of degrees / 360). You can rewrite it as (# of degrees x DME arc) ÷ 57.3. Which is close to 60.

In the example with the GNATS.ONE departure, their method gives (15*(333-251))/60 = 20.5 miles. The correct method gives (2π * 15) * (82/360) = 21.5. About 5% more.

I don”t know which method the people who wrote the test use, but if they use the incorrect method, it helps explain why none of the answers is ever the right one.

New Tools for My Toolbag

April 10th, 2017

After doing a bunch of oil changes under A&P supervision, I decided to give it a shot myself. There is not a lot of room for my big torque wrench and I don’t feel particularly comfortable using the rule of thumb method of ¾ turn past finger tight, so I bought this torque wrench specifically designed for oil filters that comes pre-set at 17 ft/lbs. of torque. Works like a charm.

Oil Filter Wrench

Cutting the oil filter without an oil filter cutter is an exercise in frustration. Put the filter in a vise and with a couple of turns, the bottom cuts right off.

Oil Filter Cutter

The other tool you will need, that might not come with your wrench set, is a 1″ box wrench to get the filter off. I also use the silicone lube, like the filter manufacturer recommends, instead of oil on the gasket.

Oil Change Notes

April 9th, 2017

Before I changed the oil on the Cherokee and Cessna 210 I took pictures of the oil filter safety wire and drain plug safety wire so that I could make sure I got it right when I redid it. So for the next time, here is what they look like.

Cherokee Oil Filter

Note how the wire is looped through the plug, wraps around the oil pan, and is tied in the hole in the oil pan. Also note the copper gasket on the plug. Don’t lose this, since it is not the same size as the spark plug gaskets and if you lose it, you’ll be down while you order another.

Cessna Oil Plug

Here’s my version. The first time I did it, I couldn’t see the image very well on the phone, but when I cropped it and blew it up, it is easy to see that the wire starts in the plug. I got the direction right, but not the order. So I tried it again. I wasn’t happy with how tight it was, so I tried it again. After five tries, I’m pretty happy with the quality. I took this picture with my iPad and I couldn’t get as good an angle.

Cessna Oil Plug My Version

Which Limitations On Approaches/Departures Apply to Part 91 Pilots?

April 7th, 2017

I answered a question on StackExchange about the meaning of Takeoff Minimum NA and indicated that they do not apply to Part 91 pilots, but after thinking about it, I’m not so sure.

§ 91.175 does require a minimum flight visibility, The flight visibility is not less than the visibility prescribed in the standard instrument approach being used; and at least one of the items in the runway environment must be visible in order to continue the approach below DA or DH. We are not bound by reported visibility or ceiling. The charted DA or DH must be complied with as well as the rest of the charted procedure, including circling minimums, direction, etc.

It is well known that takeoff minimums do not apply to Part 91 pilots, we can depart in 0/0 weather, though it might not be advisable. And the reason for that is because § 91.175 (f) Civil airport takeoff minimums. This paragraph applies to persons operating an aircraft under part 121, 125, 129, or 135 of this chapter. does not include Part 91 operators.

Fuel requirements and alternates are specifically spelled out in §91.167 and §91.169 respectively. But I can’t find anything specifically saying that you must comply with any charted limitations.

Often the reason that the runway is not available would make using it a very unwise decision. e.g. terrain or obstacles. On the other hand an unmonitored ground facility when the tower is closed wouldn’t be an issue if you were using GPS to fly the departure.

The AIM 5-2-8 just says,

Pilots operating under 14 CFR Part 91 are strongly encouraged to file and fly a DP at night, during marginal Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC), when one is available.

At a towered field with an operating control tower, they are unlikely to allow you to to takeoff under IFR on a runway marked as Takeoff Minimum NA but is there any restriction when the tower is closed or there is no tower?

I’m inclined to think that any charted restriction, noting the exceptions mentioned above, applies to Part 91 pilots. What do you think?

Pre-Flight Briefing

April 7th, 2017

Briefing

Radar Loop
Aviation Weather Center

1800WXBRIEF

Earth Wind Map
GOES Satellite – NCAR
Radar Stations – NCAR
Skew-T/Log-P diagrams – NCAR
NWS Weather Prediction Center
UNISYS

TFRs, NOTAMs, and Special Use Airspace

TFRs
NOTAMs
SUAs

GPS Availability

RAIM Prediction Tool
WAAS Availability

Decoding Reports

ASOS Guide For Pilots
TAF Decoder
AvWx Workshops

Sun and Moon Data

ForeFlight message: “geo-referencing disabled”

March 30th, 2017

This is the first chart update cycle since I upgraded to geo-refereced approach charts. While flying the simulator I got this message when I tried to add an approach to the flight plan. All of my charts are updated and I am connected to the internet so the message is puzzling. I can add the chart to the map page via the Airports/Procedures page. I’m guessing Foreflight is confused about the current date of the charts. I reset ForeFlight by double-tapping the home button to get the list of current apps and then pulling the app up off the screen. Then I started ForeFlight and it seems to be fine now.

I don’t know if you need to do this every month or if it is something that happened because I just upgraded.We’ll know next month.

Update: Seems to be a one-time thing.

AC 00-6B Aviation Weather: Icing

March 29th, 2017

In general, icing is any deposit of ice forming on an object. It is one of the major weather hazards to aviation. Icing is a cumulative hazard. The longer an aircraft collects icing, the worse the hazard becomes.

Supercooled Water
Freezing is a complex process. Pure water suspended in the air does not freeze until it reaches a temperature of -40 °C. This occurs because surface tension of the droplets inhibits freezing. The smaller and purer the water droplet, the more likely it is supercooled. Also, supercooled water can exist as large drops known as Supercooled Large Drops (SLD). SLDs are common in freezing rain and freezing drizzle situations.

Supercooled water content of clouds varies with temperature. Between 0 and -10 °C clouds consist mainly of supercooled water droplets. Between -10 and -20 °C, liquid droplets coexist with ice crystals. Below -20 °C, clouds are generally composed entirely of ice crystals. However, strong vertical currents (e.g., cumulonimbus) may carry supercooled water to great heights where temperatures are as low as -40 °C.

Supercooled water will readily freeze if sufficiently agitated. This explains why airplanes collect ice when they pass through a liquid cloud or precipitation composed of supercooled droplets.

Structural Icing
Structural icing is the stuff that sticks to the outside of the airplane. It occurs when supercooled water droplets strike the airframe and freeze. Structural icing can be categorized into three types: rime, clear (or glaze), and mixed.

Rime ice is rough, milky, and opaque ice formed by the instantaneous freezing of small, supercooled water droplets after they strike the aircraft. Rime icing formation favors colder temperatures, lower liquid water content, and small droplets. It grows when droplets rapidly freeze upon striking an aircraft. The rapid freezing traps air and forms a porous, brittle, opaque, and milky-colored ice. Rime ice grows into the air stream from the forward edges of wings and other exposed parts of the airframe.

Clear ice (or glaze ice) is a glossy, clear, or translucent ice formed by the relatively slow freezing of large, supercooled water droplets. Clear icing conditions exist more often in an environment with warmer temperatures, higher liquid water contents, and larger droplets. Clear ice forms when only a small portion of the drop freezes immediately while the remaining unfrozen portion flows or smears over the aircraft surface and gradually freezes. Few air bubbles are trapped during this gradual process.

Clear icing is a more hazardous ice type for many reasons. It tends to form horns near the top and bottom of the airfoils leading edge, which greatly affects airflow. This results in an area of disrupted and turbulent airflow that is considerably larger than that caused by rime ice. Since it is clear and difficult to see, the pilot may not be able to quickly recognize that it is occurring.

Supercooled Large Drops (SLD) is a type of clear icing that is especially dangerous to flight operations is ice formed from SLDs. These are water droplets in a subfreezing environment with diameters larger than 40 microns, such as freezing drizzle (40 to 200 microns) and freezing rain (>200 microns). These larger droplets can flow along the airfoil for some distance prior to freezing. SLDs tend to form a very lumpy, uneven, and textured ice similar to glass in a bathroom window.

Mixed ice is a mixture of clear ice and rime ice. It forms as an airplane collects both rime and clear ice due to small-scale (tens of kilometers or less) variations in liquid water content, temperature, and droplet sizes. Mixed ice appears as layers of relatively clear and opaque ice when examined from the side.

Icing Factors
Structural icing is determined by many factors. The meteorological quantities most closely related to icing type and severity are, in order of importance: Supercooled Liquid Water Content (SLWC), temperature (altitude), and droplet size. However, aircraft type/design and airspeed are also important factors.

For icing to occur, the outside air temperature must be below 0 °C. As clouds get colder, SLWC decreases until only ice crystals remain. Thus, almost all icing tends to occur in the temperature interval between 0 °C and -20 °C, with about half of all reports occurring between -8 °C and -12 °C. In altitude terms, the peak of occurrence is near 10,000 feet, with approximately half of incidents occurring between 5,000 feet and 13,000 feet. The only physical cold limit to icing is at -40 °C because liquid droplets freeze without nuclei present.

In general, rime icing tends to occur at temperatures colder than -15 °C, clear when the temperature is warmer than -10 °C, and mixed ice at temperatures in between.

Icing in Stratiform Clouds
Icing in middle and low-level stratiform clouds is confined, on the average, to a layer between 3,000 and 4,000 feet thick. Thus, a change in altitude of only a few thousand feet may take the aircraft out of icing conditions, even if it remains in clouds. High-level stratiform clouds (i.e., at temperatures colder than -20 °C) are composed mostly of ice crystals and produce little icing.

Icing in Cumuliform Clouds
The icing layer in cumuliform clouds is smaller horizontally, but greater vertically than in stratiform clouds. Icing is more variable in cumuliform clouds because many of the factors conducive to icing depend on the particular cloud’s stage of development.

Icing with Fronts
Most icing reports occur in the vicinity of fronts. This icing can occur both above and below the front. For significant icing to occur above the front, the warm air must be lifted and cooled to saturation at temperatures below zero, making it contain supercooled water droplets. The supercooled water droplets freeze on impact with an aircraft. If the warm air is unstable, icing may be sporadic; if it is stable, icing may be continuous over an extended area. A line of showers or thunderstorms along a cold front may produce icing, but only in a comparatively narrow band along the front.

A favored location for severe clear icing is freezing rain and/or freezing drizzle below a front. Rain forms above the frontal surface at temperatures warmer than freezing. Subsequently, it falls through air at temperatures below freezing and becomes supercooled. Ice pellets indicate icing above.

Icing with Mountains
Icing is more likely and more severe in mountainous regions. Mountain ranges cause upward air motions on their windward side. These vertical currents support large supercooled water droplets above the freezing level.

The most severe icing occurs above the crests and on the ridges’ windward side. This zone usually extends to about 5,000 feet above the mountaintops, but can extend much higher if cumuliform clouds develop. Icing with mountains can be especially hazardous because a pilot may be unable to descend to above freezing temperatures due to terrain elevation.

Icing Hazards
Wind tunnel and flight tests have shown that frost, snow, and ice accumulations (on the leading edge or upper surface of the wing) no thicker or rougher than a piece of coarse sandpaper can reduce lift by 30 percent and increase drag up to 40 percent. Larger accretions can reduce lift even more and can increase drag by 80 percent or more.

The airplane may stall at much higher speeds and lower angles of attack than normal. It can roll or pitch uncontrollably, and recovery might be impossible.

Test you knowledge of icing.

AC 00-6B Aviation Weather: Thunderstorms

March 29th, 2017

A thunderstorm is a local storm, invariably produced by a cumulonimbus cloud, and always accompanied by lightning and thunder, usually with strong gusts of wind, heavy rain, and sometimes with hail.

Thunderstorm cell formation requires three ingredients: sufficient water vapor, unstable air, and a lifting mechanism (see Figure 19-1).Sufficient water vapor (commonly measured using dewpoint) must be present to produce unstable air. Virtually all showers and thunderstorms form in an air mass that is classified as conditionally unstable.
A conditionally unstable air mass requires a lifting mechanism strong enough to release the instability. Lifting mechanisms include: converging winds around surface lows and troughs, fronts, upslope flow, drylines, outflow boundaries generated by prior storms, and local winds, such as sea breeze, lake breeze, land breeze, and valley breeze circulations.

Thunderstorm Cell Life Cycle
A thunderstorm cell is the convective cell of a cumulonimbus cloud having lightning and thunder. It undergoes three distinct stages during its life cycle: towering cumulus, mature, and dissipating. The total life cycle is typically about 30 minutes.

The distinguishing feature of the towering cumulus stage is a strong convective updraft. The updraft is a bubble of warm, rising air concentrated near the top of the cloud which leaves a cloudy trail in its wake. Updraft speeds can exceed 3,000 feet per minute.

The cell transitions to the mature stage when precipitation reaches the surface. Precipitation descends through the cloud and drags the adjacent air downward, creating a strong downdraft alongside the updraft. The downdraft spreads out along the surface, well in advance of the parent thunderstorm cell, as a mass of cool, gusty air.

The dissipating stage is marked by a strong downdraft embedded within the area
of precipitation. Subsiding air replaces the updraft throughout the cloud, effectively cutting off the supply of moisture provided by the updraft. Precipitation tapers off and ends. Compression warms the subsiding air and the relative humidity drops. The convective cloud gradually vaporizes from below, leaving only a remnant anvil cloud.

Thunderstorm Types
There are three principal thunderstorm types: single cell, multicell (cluster and line), and supercell.

A single cell (also called ordinary cell) thunderstorm consists of only one cell. It is easily circumnavigated by pilots, except at night or when embedded in other clouds. Single cell thunderstorms are rare; almost all thunderstorms are multicell.

A multicell cluster thunderstorm consists of a cluster of cells at various stages of their life cycle. With an organized multicell cluster, as the first cell matures, it is carried downwind, and a new cell forms upwind to take its place. A multicell cluster may have a lifetime of several hours (or more).

Sometimes thunderstorms will form a squall line that can extend laterally for hundreds of miles. New cells continually re-form at the leading edge of the system with rain, and sometimes hail, following behind. Sometimes storms which comprise the line can be supercells. The line can persist for many hours (or more) as long as the three necessary ingredients continue to exist.

A supercell thunderstorm is an often dangerous convective storm that consists primarily of a single, quasi-steady rotating updraft that persists for an extended period of time. It has a very organized internal structure that enables it to produce especially dangerous weather for pilots who encounter them. Updraft speeds may reach 9,000 feet per minute (100 knots). This allows hazards to be magnified to an even greater degree. Nearly all supercells produce severe weather (e.g., large hail or damaging wind) and about 25 percent produce a tornado. A supercell may persist for many hours (or longer).

Hazards
A thunderstorm can pack just about every aviation weather hazard into one vicious bundle. These hazards include: lightning, adverse winds, downbursts, turbulence, icing, hail, rapid altimeter changes, static electricity, and tornadoes.

A microburst is particularly dangerous during landing if the pilot has reduced power and lowered the nose in response to the headwind shear. This leaves the aircraft in a nose-low, power-low configuration when the tailwind shear occurs, which makes recovery more difficult. It can cause the airplane to stall or land short of the runway.

Rapid Altimeter Changes
Pressure usually falls rapidly with the approach of a thunderstorm, then rises sharply with gust frontal passage and arrival of heavy rain showers in the cold downdraft, falling back to normal as the storm moves away. This cycle of pressure change may occur in as little as 15 minutes.

Test you knowledge of thunderstorms.

Aviation Weather: Fronts

March 29th, 2017

AC 00-6B: Aviation Weather

Air Masses
An air mass is a large body of air with generally uniform temperature and humidity. The area from which an air mass originates is called a source region. Air mass source regions range from extensive snow-covered polar areas to deserts to tropical oceans. The United States is not a favorable source region because of the relatively frequent passage of weather disturbances that disrupt any opportunity for an air mass to stagnate and take on the properties of the underlying region. The longer the air mass stays over its source region, the more likely it will acquire the properties of the surface below.

Fronts
Air masses can control the weather for a relatively long time period ranging from days to months. Most weather occurs along the periphery of these air masses at boundaries called fronts. A front is a boundary or transition zone between two air masses. Fronts are classified by which type of air mass (cold or warm) is replacing the other.

Fronts are usually detectable at the surface in a number of ways: significant temperature gradients, or differences, exist along fronts (especially on the cold air side); winds usually converge, or come together, at fronts; and pressure typically decreases as a front approaches and increases after it passes.

Fronts do not exist only at the surface of the Earth; they have a vertical structure in which the front slopes over the colder (denser) air mass. Cold fronts have a steep slope, and the warm air is forced upward abruptly. This often leads to a narrow band of showers and thunderstorms along, or just ahead of, the front if the warm rising air is unstable. Warm fronts typically have a gentle slope, so the warm air rising along the frontal surface is gradual. This favors the development of widespread layered or stratiform cloudiness and precipitation along, and ahead of, the front if the warm rising air is stable. Stationary frontal slope can vary, but clouds and precipitation would still form in the warm rising air along the front.

Types of Fronts

FAA-H-8083-25B Pilots Handbook of Aeronautical Knowledge
Warm Front
A warm front occurs when a warm mass of air advances and replaces a body of colder air. Warm fronts move slowly, typically 10 to 25 miles per hour (mph). The slope of the advancing front slides over the top of the cooler air and gradually pushes it out of the area. Warm fronts contain warm air that often has very high humidity. As the warm air is lifted, the temperature drops and condensation occurs.

Generally, prior to the passage of a warm front, cirriform or stratiform clouds, along with fog, can be expected to form along the frontal boundary. In the summer months, cumulonimbus clouds (thunderstorms) are likely to develop

Light to moderate precipitation is probable, usually in the form of rain, sleet, snow, or drizzle, accentuated by poor visibility. The wind blows from the south-southeast, and the outside temperature is cool or cold with an increasing dew point. Finally, as the warm front approaches, the barometric pressure continues to fall until the front passes completely.

During the passage of a warm front, stratiform clouds are visible and drizzle may be falling. The visibility is generally poor, but improves with variable winds. The temperature rises steadily from the inflow of relatively warmer air. For the most part, the dew point remains steady and the pressure levels off. After the passage of a warm front, stratocumulus clouds predominate and rain showers are possible. The visibility eventually improves, but hazy conditions may exist for a short period after passage. The wind blows from the south-southwest. With warming temperatures, the dew point rises and then levels off. There is generally a slight rise in barometric pressure, followed by a decrease of barometric pressure.

Cold Front
A cold front occurs when a mass of cold, dense, and stable air advances and replaces a body of warmer air.
Cold fronts move more rapidly than warm fronts, progressing at a rate of 25 to 30 mph. However, extreme cold fronts have been recorded moving at speeds of up to 60 mph. A typical cold front moves in a manner opposite that of a warm front. It is so dense, it stays close to the ground and acts like a snowplow, sliding under the warmer air and forcing the less dense air aloft. The rapidly ascending air causes the temperature to decrease suddenly, forcing the creation of clouds. The type of clouds that form depends on the stability of the warmer air mass. A cold front in the Northern Hemisphere is normally oriented in a northeast to southwest manner and can be several hundred miles long, encompassing a large area of land.

Prior to the passage of a typical cold front, cirriform or towering cumulus clouds are present, and cumulonimbus clouds may develop. Rain showers may also develop due to the rapid development of clouds. A high dew point and falling barometric pressure are indicative of imminent cold front passage.

As the cold front passes, towering cumulus or cumulonimbus clouds continue to dominate the sky. Depending on the intensity of the cold front, heavy rain showers form and may be accompanied by lightning, thunder, and/or hail. More severe cold fronts can also produce tornadoes. During cold front passage, the visibility is poor with winds variable and gusty, and the temperature and dew point drop rapidly. A quickly falling barometric pressure bottoms out during frontal passage, then begins a gradual increase.

After frontal passage, the towering cumulus and cumulonimbus clouds begin to dissipate to cumulus clouds with a corresponding decrease in the precipitation. Good visibility eventually prevails with the winds from the west-northwest. Temperatures remain cooler and the barometric pressure continues to rise.

Fast-Moving Cold Front
Fast-moving cold fronts are pushed by intense pressure systems far behind the actual front. The friction between the ground and the cold front retards the movement of the front and creates a steeper frontal surface. This results in a very narrow band of weather, concentrated along the leading edge of the front. If the warm air being overtaken by the cold front is relatively stable, overcast skies and rain may occur for some distance behind the front. If the warm air is unstable, scattered thunderstorms and rain showers may form. A continuous line of thunderstorms, or squall line, may form along or ahead of the front. Squall lines present a serious hazard to pilots as squall-type thunderstorms are intense and move quickly. Behind a fast-moving cold front, the skies usually clear rapidly, and the front leaves behind gusty, turbulent winds and colder temperatures.

Violent weather activity is associated with cold fronts, and the weather usually occurs along the frontal boundary, not in advance. However, squall lines can form during the summer months as far as 200 miles in advance of a strong cold front. Warm fronts bring low ceilings, poor visibility, and rain, cold fronts bring sudden storms, gusty winds, turbulence, and sometimes hail or tornadoes.
Cold fronts are fast approaching with little or no warning, and they bring about a complete weather change in just a few hours. The weather clears rapidly after passage and drier air with unlimited visibilities prevail. Warm fronts, on the other hand, provide advance warning of their approach and can take days to pass through a region.

Stationary Front
When the forces of two air masses are relatively equal, the boundary or front that separates them remains stationary and influences the local weather for days. This front is called a stationary front. The weather associated with a stationary front is typically a mixture that can be found in both warm and cold fronts.

Occluded Front
An occluded front occurs when a fast-moving cold front catches up with a slow-moving warm front. As the occluded front approaches, warm front weather prevails but is immediately followed by cold front weather. There are two types of occluded fronts that can occur, and the temperatures of the colliding frontal systems play a large part in defining the type of front and the resulting weather. A cold front occlusion occurs when a fast moving cold front is colder than the air ahead of the slow moving warm front. When this occurs, the cold air replaces the cool air and forces the warm front aloft into the atmosphere. Typically, the cold front occlusion creates a mixture of weather found in both warm and cold fronts, providing the air is relatively stable. A warm front occlusion occurs when the air ahead of the warm front is colder than the air of the cold front. When this is the case, the cold front rides up and over the warm front. If the air forced aloft by the warm front occlusion is unstable, the weather is more severe than the weather found in a cold front occlusion. Embedded thunderstorms, rain, and fog are likely to occur.

Prior to the passage of the typical occluded front, cirriform and stratiform clouds prevail, light to heavy precipitation falls, visibility is poor, dew point is steady, and barometric pressure drops. During the passage of the front, nimbostratus and cumulonimbus clouds predominate, and towering cumulus clouds may also form. Light to heavy precipitation falls, visibility is poor, winds are variable, and the barometric pressure levels off. After the passage of the front, nimbostratus and altostratus clouds are visible, precipitation decreases, and visibility improves.

Test your knowledge of fronts.

AC 00-6B Aviation Weather: Part 2

March 28th, 2017

Vertical Motion and Cloud Formation
A cloud is a visible aggregate of minute water droplets and/or ice particles in the atmosphere above the Earth’s surface. Fog differs from cloud only in that the base of fog is at the Earth’s surface while clouds are above the surface.

Clouds form in the atmosphere as a result of condensation of water vapor in rising currents of air, or by the evaporation of the lowest layer of fog. Rising currents of air are necessary for the formation of vertically deep clouds capable of producing precipitation heavier than light intensity.

Vertical Motion Effects on an Unsaturated Air Parcel
As a bubble or parcel of air ascends (rises), the pressure decreases with height. As this occurs, the parcel expands. This requires energy, or work, which takes heat away from the parcel, so the air cools as it rises. This is called an adiabatic process. The term adiabatic means that no heat transfer occurs into, or out of, the parcel. Air has low thermal conductivity, so transfer of heat by conduction is negligibly small.

The rate at which the parcel cools as it is lifted is called the lapse rate. The lapse rate of a rising, unsaturated parcel (air with relative humidity less than 100 percent) is approximately 3 °C per 1,000 feet (9.8 °C per kilometer). This is called the dry adiabatic lapse rate. Concurrently, the dewpoint decreases approximately 0.5 °C per 1,000 feet (1.8 °C per kilometer). The parcel’s temperature-dewpoint spread decreases, while its relative humidity increases.

This process is reversible if the parcel remains unsaturated and, thus, does not lose any water vapor. A descending (subsiding) air parcel compresses. The atmosphere surrounding the parcel does work on the parcel, and energy is added to the compressed parcel, which warms it. Thus, the temperature of a descending air parcel increases approximately 3 °C per 1,000 feet.

The Lifting Condensation Level (LCL) is the level at which a parcel of moist air lifted dry adiabatically becomes saturated. At this altitude, the temperature-dewpoint spread is zero and relative humidity is 100 percent.

Further lifting of the saturated parcel results in condensation, cloud formation, and latent heat release. Because the heat added during condensation offsets some of the cooling due to expansion, the parcel now cools at the moist adiabatic lapse rate, which varies between approximately 1.2 °C per 1,000 feet (4 °C per kilometer) for very warm saturated parcels to 3 °C per 1,000 feet (9.8 °C per kilometer) for very cold saturated parcels.

As the saturated air parcel expands and cools, however, its water vapor content decreases. This occurs because some of the water vapor is condensed to water droplets or deposited into ice crystals to form a cloud. This process is triggered by the presence of microscopic cloud condensation (and ice) nuclei, such as dust, clay, soot, sulfate, and sea salt particles. The cloud grows vertically deeper as the parcel continues to rise.

Common Sources of Vertical Motion
Orographic Effects
Winds blowing across mountains and valleys cause the moving air to alternately ascend and descend.

Frictional Effects
In the Northern Hemisphere, the surface wind spirals clockwise and outward from high pressure, and counterclockwise and inward into low pressure due to frictional force. The end result is that winds diverge away from surface high pressure, causing the air to sink, compress, and warm, which favors the dissipation of clouds and precipitation. Conversely, winds converge into surface low pressure, causing the air to rise, expand, and cool, which favors the formation of clouds and precipitation given sufficient moisture

Frontal Lift
Frontal lift occurs when the cold, denser air wedges under the warm, less dense air, plowing it upward, and/or the warmer air rides up and over the colder air in a process called overrunning. Cloud and precipitation will form given sufficient lift and moisture content of the warm air.

Buoyancy
Air near the ground can warm at different rates depending on the insular properties of the ground with which it is in contact.

Measurements of Stability
Several stability indexes and other quantities exist that evaluate atmospheric stability and the potential for convective storms. The most common of these are Lifted Index (LI) and Convective Available Potential Energy (CAPE).

Lifted Index
The LI is the temperature difference between an air parcel (usually at the surface) lifted adiabatically and the temperature of the environment at a given pressure (usually 500 millibars) in the atmosphere. A positive value indicates a stable column of air (at the respective pressure), a negative value indicates an unstable column of air, and a value of zero indicates a neutrally stable column of air. The larger the positive (negative) LI value, the more stable (unstable) the column of air.

Convective Available Potential Energy
CAPE is the maximum amount of energy available to an ascending air parcel for convection. CAPE is represented on a sounding by the area enclosed between the environmental temperature profile and the path of a rising air parcel over the layer within which the latter is warmer than the former. Units are joules per kilogram of air (J/kg). Any value greater than 0 joules per kilogram indicates instability and the possibility of thunderstorms.

CAPE is directly related to the maximum potential vertical speed within an updraft; thus, higher values indicate the potential for stronger updrafts. Observed values in thunderstorm environments often exceed 1,000 joules per kilogram, and in extreme cases may exceed 5,000 joules per kilogram.

Precipitation
Precipitation is any of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground. The precipitation types are: drizzle, rain, snow, snow grains, ice crystals, ice pellets, hail, and small hail and/or snow pellets.

Precipitation formation requires three ingredients: water vapor, sufficient lift to condense the water vapor into clouds, and a growth process that allows cloud droplets to grow large and heavy enough to fall as precipitation. Significant precipitation usually requires clouds to be at least 4,000 feet thick. The heavier the precipitation, the thicker the clouds are likely to be.

Growth Process
An average cloud droplet falling from a cloud base at 3,300 feet (1,000 meters) would require about 48 hours to reach the ground. It would never complete this journey because it would evaporate within minutes after falling below the cloud base.

In the collision-coalescence, or warm rain process, collisions occur between cloud droplets of varying size and different fall speeds, sticking together or coalescing to form larger drops. Finally, the drops become too large to be suspended in the air, and they fall to the ground as rain. This is thought to be the primary growth process in warm, tropical air masses where the freezing level is very high.

The other process is the ice crystal process. This occurs in colder clouds when both ice crystals and water droplets are present. In this situation, it is easier for water vapor to deposit directly onto the ice crystals so the ice crystals grow at the expense of the water droplets. The crystals eventually become heavy enough to fall. If it is cold near the surface, it may snow; otherwise, the snowflakes may melt to rain. This is thought to be the primary growth process in mid- and high-latitudes.

Precipitation Types
Snow occurs when the temperature remains below freezing throughout the entire depth of the atmosphere.

Ice pellets (sleet) occur when there is a shallow layer aloft with above freezing temperatures and with a deep layer of below freezing air based at the surface. As snow falls into the shallow warm layer, the snowflakes partially melt. As the precipitation reenters air that is below freezing, it refreezes into ice pellets.

Freezing rain occurs when there is a deep layer aloft with above freezing temperatures and with a shallow layer of below freezing air at the surface. It can begin as either rain and/or snow, but becomes all rain in the warm layer. The rain falls back into below freezing air, but since the depth is shallow, the rain does not have time to freeze into ice pellets. The drops freeze on contact with the ground or exposed objects.

Rain occurs when there is a deep layer of above freezing air based at the surface.

Adverse Wind
Adverse wind is a category of hazardous weather that is responsible for many weather-related accidents. Adverse winds include: crosswinds, gusts, tailwind, variable wind, and a sudden wind shift.

A crosswind is a wind that has a component directed perpendicularly to the heading of an aircraft.

A gust is a fluctuation of wind speed with variations of 10 knots or more between peaks and lulls.

A tailwind is a wind with a component of motion from behind the aircraft.

A variable wind is a wind that changes direction frequently, while a sudden wind shift is a line or narrow zone along which there is an abrupt change of wind direction.

Wind shear is the change in wind speed and/or direction, usually in the vertical.

Weather and Obstructions to Visibility
Weather and obstructions to visibility include: fog, mist, haze, smoke, precipitation, blowing snow, dust storm, sandstorm, and volcanic ash.

Fog
Fog forms when the temperature and dewpoint of the air become identical (or nearly so). This may occur through cooling of the air to a little beyond its dewpoint (producing radiation fog, advection fog, or upslope fog), or by adding moisture and thereby elevating the dewpoint (producing frontal fog or steam fog). Fog seldom forms when the temperature-dewpoint spread is greater than 2 °C (4 °F).

Advection Fog
Advection fog forms when moist air moves over a colder surface, and the subsequent cooling of that air to below its dewpoint. It is most common along coastal areas, but often moves deep in continental areas. At sea, it is called sea fog. Advection fog deepens as wind speed increases up to about 15 knots. Wind much stronger than 15 knots lifts the fog into a layer of low stratus or stratocumulus clouds.

Upslope Fog
Upslope fog forms as a result of moist, stable air being adiabatically cooled to or below its dewpoint as it moves up sloping terrain. Winds speeds of 5 to 15 knots are most favorable since stronger winds tend to lift the fog into a layer of low stratus clouds.

Frontal Fog
When warm, moist air is lifted over a front, clouds and precipitation may form. If the cold air below is near its dewpoint, evaporation (or sublimation) from the precipitation may saturate the cold air and form fog. The result is a more or less continuous zone of condensed water droplets reaching from the ground up through the clouds.

Steam Fog
When very cold air moves across relatively warm water, enough moisture may evaporate from the water surface to produce saturation. As the rising water vapor meets the cold air, it immediately recondenses and rises with the air that is being warmed from below. Because the air is destabilized, fog appears as rising filaments or streamers that resemble steam.

Mist
Mist is a visible aggregate of minute water droplets or ice crystals suspended in the atmosphere that reduces visibility to less than 7 statute miles (11 kilometers), but greater than, or equal to, 5/8 statute mile (1 kilometer).

Haze
Haze is a suspension in the air of extremely small particles invisible to the naked eye and sufficiently numerous to give the air an opalescent appearance. It reduces visibility by scattering the shorter wavelengths of light. Haze produces a bluish color when viewed against a dark background and a yellowish veil when viewed against a light background. Haze may be distinguished by this same effect from mist, which yields only a gray obscuration.

Smoke
Smoke is a suspension in the air of small particles produced by combustion due to fires, industrial burning, or other sources. It may transition to haze when the particles travel 25-100 miles (40-160 kilometers) or more, and the larger particles have settled and others become widely scattered through the atmosphere.

Precipitation
Precipitation is any of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground. Snow, rain, and drizzle are types of precipitation.

Blowing Snow
Blowing snow is snow lifted from the surface of the Earth by the wind to a height of 6 feet (2 meters) or more above the ground, and blown about in such quantities that the reported horizontal visibility is reduced to less than 7 statute miles (11 kilometers).

Turbulence
Aircraft turbulence is irregular motion of an aircraft in flight, especially when characterized by rapid up-and-down motion caused by a rapid variation of atmospheric wind velocities. Turbulence is caused by convective currents (called convective turbulence), obstructions in the wind flow (called mechanical turbulence), and wind shear.

Convective Turbulence
Convective turbulence is turbulent vertical motions that result from convective currents and the subsequent rising and sinking of air. As air moves upward, it cools by expansion. A convective current continues upward until it reaches a level where its temperature cools to the same as that of the surrounding air. If it cools to saturation, a cumuliform cloud forms. Billowy cumuliform clouds, usually seen over land during sunny afternoons, are signposts in the sky indicating convective turbulence.

When the air is too dry for cumuliform clouds to form, convective currents can still be active. This is called dry convection, or thermals.

Mechanical Turbulence
Mechanical turbulence is turbulence caused by obstructions to the wind flow, such as trees, buildings, mountains, and so on. Obstructions to the wind flow disrupt smooth wind flow into a complex snarl of eddies.

Mountain waves are a form of mechanical turbulence which develop above and downwind of mountains. The waves remain nearly stationary while the wind blows rapidly through them. The waves may extend 600 miles (1,000 kilometers) or more downwind from the mountain range.

When sufficient moisture is present in the upstream flow, mountain waves produce interesting cloud formations including: cap clouds, cirrocumulus standing lenticular (CCSL), Altocumulus Standing Lenticular (ACSL), and rotor clouds. These clouds provide visual proof that mountain waves exist. However, these clouds may be absent if the air is too dry.

Wind Shear Turbulence
Wind shear is the rate of change in wind direction and/or speed per unit distance. Wind shear generates turbulence between two wind currents of different directions and/or speeds.

A temperature inversion is a layer of the atmosphere in which temperature increases with altitude. Inversions commonly occur within the lowest few thousand feet above ground due to nighttime radiational cooling, along frontal zones, and when cold air is trapped in a valley. Strong wind shears often occur across temperature inversion layers.

Clear Air Turbulence (CAT) is a higher altitude (~20,000 to 50,000 feet) turbulence phenomenon occurring in cloud-free regions associated with wind shear, particularly between the core of a jet stream and the surrounding air.

AC 00-6B Aviation Weather: Part 1

March 27th, 2017

Weather is not a capricious act of nature, but rather the atmosphere’s response to unequal rates of radiational heating and cooling across the surface of the Earth and within its atmosphere.

Troposphere.
The troposphere begins at the Earth’s surface and extends up to about 11 kilometers (36,000 feet) high.

The vertical depth of the troposphere varies due to temperature variations which are closely associated with latitude and season. It decreases from the Equator to the poles, and is higher during summer than in winter. At the Equator, it is around 18-20 kilometers (11-12 miles) high, at 50° N and 50° S latitude, 9 kilometers (5.6 miles), and at the poles, 6 kilometers (3.7 miles) high. Knowledge tests asks in feet: Average: 37,000′, poles: 25,000-30,000′, mid-latitudes: 25,000′, equator: 55,000-65,000′.

Tropopause
The transition boundary between the troposphere and the stratosphere.

Stratosphere
The stratosphere extends from the tropopause up to 50 kilometers (31 miles) above the Earth’s surface. This layer holds 19 percent of the atmosphere’s gases, but very little water vapor.

Temperature increases with height as radiation is increasingly absorbed by oxygen molecules, leading to the formation of ozone. The temperature rises from an average -56.6 °C (-70 °F) at the tropopause to a maximum of about -3 °C (27 °F) at the stratopause due to this absorption of ultraviolet radiation. The increasing temperature also makes it a calm layer, with movements of the gases being slow.

Mesosphere
The mesosphere extends from the stratopause to about 85 kilometers (53 miles) above the Earth. On average, temperature decreases from about -3 °C (27 °F) to as low as -100 °C (-148 °F) at the mesopause.

Thermosphere.
The thermosphere extends from the mesopause to 690 kilometers (430 miles) above the Earth. This layer is known as the upper atmosphere.

Thermopause
The transition boundary that separates the exosphere from the thermosphere.

Exosphere
The exosphere is the outermost layer of the atmosphere, and extends from the thermopause to 10,000 kilometers (6,200 miles) above the Earth.

Standard Atmosphere
1013.25 Hectopascals
15°C

29.92 Inches of Mercury
59°F

Lapse rate 2°C per 1,000′

Thermal Response
Water has the highest specific heat capacity of any naturally occurring substance. That means it has a much higher capacity for storing heat energy than other substances, such as soil, sand, rock, or air. Water can store large amounts of heat energy while only experiencing a small temperature change. A body of water exhibits greater resistance to temperature change, called thermal inertia, than does a land mass.

Water temperature changes occur to depths of six meters (20 feet) or more on a daily basis, and 200 to 600 meters (650 to 1950 feet) annually. Over land heat must be transferred via the slow process of conduction. Land temperature changes occur to depths of only 10 centimeters (4 inches) on a daily basis and 15 meters (50 feet) or less annually.

Temperature Inversion
A surface-based inversion typically develops over land on clear nights when wind is light. The ground radiates and cools much faster than the overlying air. Air in contact with the ground becomes cool, while the temperature a few hundred feet above changes very little. Thus, temperature increases with height.

An inversion may also occur at any altitude when conditions are favorable. For example, a current of warm air aloft overrunning cold air near the surface produces an inversion aloft. Inversions are common in the stratosphere.

The principal characteristic of an inversion layer is its marked stability, so that very little turbulence can occur within it.

Temperature-Dewpoint Spread (Dewpoint Depression)
Surface temperature-dewpoint spread is important in anticipating fog, but has little bearing on precipitation. To support precipitation, air must be saturated through thick layers aloft.

Sensible Heating
Sensible heating involves both conduction and convection. It occurs due to differences in air density. Warm air is less dense than cool air. Because air is a poor conductor of heat, convection is much more important than conduction as a heat transport mechanism within the atmosphere.

Latent Heat
The phase transition of water and associated latent heat exchanges are largely responsible for transferring the excess heat from the surface of the Earth into its atmosphere. As the Earth’s surface absorbs radiation, some of the heat produced is used to evaporate (vaporize) water from oceans, lakes, rivers, soil, and vegetation. The water absorbs heat energy due to the latent heat of vaporization. Some of this water vapor condenses to microscopic water droplets or deposits as ice crystals that are visible as clouds. During cloud formation, the water vapor changes state, and latent heat is released into the atmosphere. During this process, the excess heat is transferred from the Earth’s surface into its atmosphere.

Heat Imbalance Variations with Latitude
About 35° latitude in both hemispheres is where incoming and outgoing radiation is equal. The excess heat in the tropics must be transported polar by some mechanism(s). This poleward heat transport is accomplished by atmospheric circulations, weather, and ocean currents.

Sea Level Pressure
Since pressure varies greatly with altitude, we cannot readily compare station pressures between stations at different altitudes. To make them comparable, we adjust them to some common level. Mean sea level (MSL) is the most useful common reference.

Sea Level Pressure Analyses (Surface Chart)
After plotting sea level pressure on a surface chart, lines are drawn connecting points of equal sea level pressure. These lines of equal pressure are isobars. Hence, the surface chart is an isobaric analysis showing identifiable, organized pressure patterns. Four pressure systems are commonly identified: low, high, trough and ridge.

Low: A minimum of atmospheric pressure in two dimensions (closed isobars) on a surface chart, or a minimum of height (closed contours) on a constant pressure chart. Also known as a cyclone.

High: A maximum of atmospheric pressure in two dimensions (closed isobars) on a surface chart, or a maximum of height (closed contours) on a constant pressure chart. Also known as an anticyclone.

Trough: An elongated area of relatively low atmospheric pressure.

Ridge: An elongated area of relatively high atmospheric pressure.

Surface Analysis

Constant Pressure Surface Analysis (Upper Air Chart)
These heights measured by the rawinsonde (and other types of instruments) are plotted on a constant pressure chart and analyzed by drawing a line connecting points of equal height. These lines are called height contours.

These charts can be found at the Standard Briefing page for various pressures. Here’s the one for 700MB ~10,000′.

Surface Analysis

Density
Density is directly related to pressure. Assuming constant mass and temperature, an air parcel with a higher pressure is denser than an air parcel with a lower pressure.

Density is inversely related to temperature. Assuming constant mass and pressure, an air parcel with a higher temperature is less dense than an air parcel with a lower temperature. In the atmosphere, temperature has the most effect on density in the horizontal direction; that is, with horizontal changes of location.

Density of an air parcel is inversely related to its quantity of water vapor. Assuming constant pressure, temperature, and volume, air with a greater amount of water vapor is less dense than air with a lesser amount of water vapor. This is because dry air molecules have a larger mass (weight) than water vapor molecules, and density is directly related to mass.

Altitude

True Altitude
Since existing conditions in a real atmosphere are seldom standard, altitude indications on the altimeter are seldom actual or true altitudes. True altitude is the actual vertical distance above MSL.

Indicated Altitude
Indicated altitude is the altitude above MSL indicated on the altimeter when set at the local altimeter setting.

Altimeter Setting
Since the altitude scale is adjustable, a pilot can set the altimeter to read true altitude at some specified height. Takeoff and landing are the most critical phases of flight; therefore, airport elevation is the most desirable altitude for a true reading of the altimeter. The altimeter setting is the value to which the scale of the pressure altimeter is set so the altimeter indicates true altitude at field elevation.

Corrected (Approximately True) Altitude.
If a pilot could always determine mean temperature of a column of air between the aircraft and the surface, flight computers would be designed to use this mean temperature in computing true altitude. However, the only guide a pilot has to temperature below him is free air temperature at his altitude. Therefore, the flight computer uses outside air temperature to correct indicated altitude to approximate true altitude. The corrected (approximately true) altitude is indicated altitude corrected for the temperature of the air column below the aircraft, the correction being based on the estimated deviation of the existing temperature from standard atmosphere temperature. It is a close approximation to true altitude and is labeled true altitude on flight computers. It is close enough to true altitude to be used for terrain clearance, provided the pilot has his altimeter set to the value reported from a nearby reporting station.

Pressure Altitude
In the standard atmosphere, sea level pressure is 29.92 inches of mercury (1013.2 millibars). Pressure decreases at a fixed rate upward through the standard atmosphere. Therefore, in the standard atmosphere, a given pressure exists at any specified altitude. Pressure altitude is the altitude (above MSL) shown by the altimeter when set to 29.92 inches of mercury.

Density Altitude
Density altitude is the pressure altitude corrected for temperature deviations from the standard atmosphere. Density altitude bears the same relation to pressure altitude as true altitude does to indicated altitude.

Density altitude equals field elevation during standard atmospheric conditions, but conditions are rarely standard. Density altitude is higher (lower) than standard at airports that report lower (higher) than standard pressures (29.92 inches of mercury) and/or higher (lower) than standard temperatures. Temperature is the most important factor since temperature has the greatest effect on density horizontally in the atmosphere.

Density altitude and aircraft performance.
Higher (lower) density altitude decreases (increases) performance. High density altitude is a hazard since it reduces aircraft performance in the following three ways:
  1. It reduces power because the engine takes in less air to support combustion.
  2. It reduces thrust because there is less air for the propeller to work with, or a jet has less mass of gases to force out of the exhaust.
  3. It reduces lift because the light air exerts less force on the airfoils.

The aircraft lifts off, climbs, cruises, glides, and lands at the prescribed indicated airspeeds; but at a specified indicated airspeed, the pilot’s true airspeed and groundspeed increase proportionally as density altitude becomes higher.

The net results are that high density altitude lengthens a pilot’s takeoff, and landing rolls and reduces his or her rate of climb. Before lift-off, the plane must attain a faster groundspeed, and, therefore, needs more runway; and the reduced power and thrust add a need for still more runway. The plane lands at a faster groundspeed and, therefore, needs more room to stop. At a prescribed indicated airspeed, it is flying at a faster true airspeed, and, therefore, covers more distance in a given time, which means climbing at a shallower angle. Adding to this are the problems of reduced power and rate of climb.

Forces That Affect the Wind
Three primary forces affect the flow of wind: Pressure Gradient Force (PGF), Coriolis force, and friction.

Pressure Gradient Force (PGF)
Wind is driven by pressure differences which create a force called the Pressure Gradient Force (PGF). Whenever a pressure difference develops over an area, the PGF makes the wind blow in an attempt to equalize pressure differences. This force is identified by height contour gradients on constant pressure charts and by isobar gradients on surface charts.

The wind would flow from high to low pressure if the PGF was the only force acting on it. However, because of the Earth’s rotation, there is a second force called the Coriolis force that affects the direction of wind flow.

Coriolis Force
A moving mass travels in a straight line until acted on by some outside force. However, if one views the moving mass from a rotating platform, the path of the moving mass relative to his platform appears to be deflected or curved.

The force deflects air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. Coriolis force is at a right angle to wind direction and directly proportional to wind speed; that is, as wind speed increases, Coriolis force increases. At a given latitude, double the wind speed and you double the Coriolis force.

Coriolis force varies with latitude from zero at the Equator to a maximum at the poles. It influences wind direction everywhere except immediately at the Equator, but the effects are more pronounced in middle and high latitudes. At a given latitude, double the wind speed and you double the Coriolis force.

Friction Force
Friction between the wind and the terrain surface slows the wind. The rougher the terrain, the greater the frictional effect. Also, the stronger the wind speed, the greater the friction.

Upper Air Wind
In the atmosphere above the friction layer (lowest few thousand feet), only PGF and Coriolis force affect the horizontal motion of air. Remember that the PGF drives the wind and is oriented perpendicular to height contours. When a PGF is first established, wind begins to blow from higher to lower heights directly across the contours. However, the instant air begins moving, Coriolis force deflects it to the right. Soon the wind is deflected a full 90° and is parallel to the contours. At this time, Coriolis force exactly balances PGF. With the forces in balance, wind will remain parallel to contours. This is called the geostrophic wind.

Upper Air Wind

Surface Wind
At the surface of the Earth, all three forces come into play. As frictional force slows the wind speed, Coriolis force decreases. However, friction does not affect PGF. PGF and Coriolis force are no longer in balance. The stronger PGF turns the wind at an angle across the isobars toward lower pressure until the three forces balance

Surface Wind Forces

The angle of surface wind to isobars is about 10° over water, increasing to as high as 45° over rugged terrain. The end result is, in the Northern Hemisphere, the surface wind spirals clockwise and outward from high pressure, and counterclockwise and inward into low pressure (see Figure 7-11). In mountainous regions, one often has difficulty relating surface wind to pressure gradient because of immense friction, and also because of local terrain effects on pressure.

Surface Wind Flow

Jet Streams
Jet streams are relatively narrow bands of strong wind in the upper levels of the atmosphere. The winds blow from west to east in jet streams, but the flow often meanders southward and northward in waves. Jet streams follow the boundaries between hot and cold air. Since these hot and cold air boundaries are most pronounced in winter, jet streams are the strongest for both the Northern and Southern Hemisphere winters.

The momentum of air as it travels around the Earth is conserved, which means as the air that is over the Equator starts moving toward one of the poles, it keeps its eastward motion constant. The Earth below the air, however, moves slower, as that air travels toward the poles. The result is that the air moves faster and faster in an easterly direction (relative to the Earth’s surface below) the farther it moves from the Equator.

In addition, with the three cell circulations mentioned previously, the regions around 30° N/S and 50°-60° N/S are areas where temperature changes are the greatest. As the difference in temperature between the two locations increases, the strength of the wind increases. Therefore, the regions around 30° N/S and 50°-60° N/S are also regions where the wind in the upper atmosphere is the strongest.

Cell Circulations

The jet stream is often indicated by a line on maps, and shown by television meteorologists. The line generally points to the location of the strongest wind. In reality, jet streams are typically much wider. They are less a distinct location, and more a region where winds increase toward a core of highest speed.

Local Winds
Local winds are small-scale wind field systems driven by diurnal heating or cooling of the ground. Air temperature differences develop over adjacent surfaces. Air in contact with the ground heats during the day and cools at night. Low-level pressure gradients develop with higher pressure over the cooler, denser air, and lower pressure over the warmer, less dense air.

Low-level winds develop in the direction of the Pressure Gradient Force (PGF). Coriolis force is insignificant because the circulation’s dimension (less than 100 miles) and life span (less than 12 hours) are too short for significant Coriolis deflection. Thus, the wind generally blows from a high-pressure cool surface to a low-pressure warm surface.

Rod Machado’s Five Step Teaching Process

March 25th, 2017

Identify the Big Picture
Define Your Objectives in Behavioral Terms
Simulate Experience
Identify the Specific Clues You Use and Give These To Your Students
Critique the Behavior Not the Student.

FAA Order JO 7110.65W Air Traffic Control.

March 22nd, 2017

I ran across this order when researching the previous post. If you want to know what ATC is going to have you do, this order will give you a heads-up.

This order prescribes air traffic control procedures and phraseology for use by personnel providing air traffic control services. Controllers are required to be familiar with the provisions of this order that pertain to their operational responsibilities and to exercise their best judgment if they encounter situations not covered by it.

Timed Approaches From a Holding Fix

March 22nd, 2017

I had never heard of this or seen an approach with a holding fix at the FAF or outer marker when I ran across a question on timed approaches from a holding fix in Gardner’s Complete Advanced Pilot. As you can see from the quotes at the bottom of the post, it is unlikely to ever be used. But they are still available to the controller, FAA Order JO 7110.65W Air Traffic Control.

FAA_H_8083-15B Instrument Flying Handbook 2012
Timed approaches from a holding fix are conducted when many aircraft are waiting for an approach clearance. Although the controller does not specifically state “timed approaches are in progress,” the assigning of a time to depart the FAF inbound (nonprecision approach), or the outer marker or fix used in lieu of the outer marker inbound (precision approach), indicates that timed approach procedures are being utilized.

In lieu of holding, the controller may use radar vectors to the final approach course to establish a distance between aircraft that ensures the appropriate time sequence between the FAF and outer marker or fix used in lieu of the outer marker and the airport. Each pilot in the approach sequence is given advance notice of the time they should leave the holding point on approach to the airport. When a time to leave the holding point is received, the pilot should adjust the flightpath in order to leave the fix as closely as possible to the designated time.

Timed approaches may be conducted when the following conditions are met:
1. A control tower is in operation at the airport where the approaches are conducted.
2. Direct communications are maintained between the pilot and the Center or approach controller until the pilot is instructed to contact the tower.
3. If more than one MAP is available, none require a course reversal.
4. If only one MAP is available, the following conditions are met:
  a) Course reversal is not required; and
  b) Reported ceiling and visibility are equal to or greater than the highest prescribed circling minimums for the IAP.
5. When cleared for the approach, pilots should not execute a procedure turn.

Timed Approaches From Holding Fix Chart

The AIM has an example of how they might be used.

Timed Approaches From Holding Fix

Ths actual order specifies that Timed approaches using either nonradar procedures or radar vectors to the final approach course may be used at airports served by a tower if the following conditions are met and goes on to give similar conditions.

The sons of the guys who wrote that procedure are now in the “Old Controllers’ Home”, I can only guess at their intent. The last time I had to run timed approaches was when I was taking non-radar problems to certify on Denver Sector 26 (COS/PUB low) in 1968! R Butler – ATC Controller

We did some timed approaches when I worked a U.S. non-radar approach control in the ’80s. Don’t believe there are any non-radar approach controls left, and I don’t know a single radar controller who would try it if there were a radar outage of some sort. We also had to run them at the FAA Academy in training back in the ’70s. You would need to assign different missed approaches to succeeding aircraft, so #2 doesn’t catch #1 on the miss.
It’s a lot of radio and brain work to do successfully. Non-radar at a radar facility, (because of an outage) is usually very limited now. (One in, one out) Backup radar systems preferred, even if not as accurate.
vector4fun

Vg diagram explained | Load Factor and Accelerated Stalls

March 21st, 2017

FAA-H-8083-25B Pilots Handbook of Aeronautical Knowledge

Vg Diagram
The flight operating strength of an aircraft is presented on a graph whose vertical scale is based on load factor. The diagram is called a Vg diagram—velocity versus G loads or load factor. Each aircraft has its own Vg diagram that is valid at a certain weight and altitude.

If the aircraft is flown at a positive load factor greater than the positive limit load factor, structural damage is possible. When the aircraft is operated in this region, objectionable permanent deformation of the primary structure may take place and a high rate of fatigue damage is incurred. Operation above the limit load factor must be avoided in normal operation.

There are two other points of importance on the Vg diagram. One point is the intersection of the positive limit load factor and the line of maximum positive lift capability. The airspeed at this point is the minimum airspeed at which the limit load can be developed aerodynamically. Any airspeed greater than this provides a positive lift capability sufficient to damage the aircraft. Conversely, any airspeed less than this does not provide positive lift capability sufficient to cause damage from excessive flight loads. The usual term given to this speed is “maneuvering speed,” since consideration of subsonic aerodynamics would predict minimum usable turn radius or maneuverability to occur at this condition. The maneuver speed is a valuable reference point, since an aircraft operating below this point cannot produce a damaging positive flight load. Any combination of maneuver and gust cannot create damage due to excess airload when the aircraft is below the maneuver speed.

The other point of importance on the Vg diagram is the intersection of the negative limit load factor and line of maximum negative lift capability. Any airspeed greater than this provides a negative lift capability sufficient to damage the aircraft; any airspeed less than this does not provide negative lift capability sufficient to damage the aircraft from excessive flight loads.

Maneuvering speed at gross weight can be found in the Type Certificate Data Sheet for your airplane. Newer airplanes also have it in the Airplane Flight Manual or Pilots Handbook. Maximum structural cruising speed and never exceed speed are found on your airspeed indicator.

The very best explanation of maneuvering speed that I have seen is in this video by Rod Machado.

And this one explains why maneuvering speed varies with weight.

Rule of thumb: For every 2% decrease in aircraft weight from max gross, decrease maneuvering speed by 1%.

SBAS

March 15th, 2017

I was reading the Airplane Flight Manual Supplement for my Garmin 430W and ran across this acronym.

GPS/SBAS TSO-C146a Class 3 Operation
The GNS complies with AC 20-138A and has airworthiness approval for navigation using GPS and SBAS (within the coverage of a Satellite Based Augmentation System complying with ICAO Annex 10) for IFR en route, terminal area, and non-precision approach operations (including those approaches titled “GPS”, “or GPS”, and “RNAV (GPS)” approaches). The Garmin GNSS navigation system is composed of the GNS navigator and antenna, and is approved for approach procedures with vertical guidance including “LPV” and “LNAV/VNAV” and without vertical guidance including “LP” and “LNAV,” within the U.S. National Airspace System.

AIM 1−1−18. Wide Area Augmentation System (WAAS)
WAAS 2. The International Civil Aviation Organization (ICAO) has defined Standards and Recommended Practices (SARPs) for satellite−based augmentation systems (SBAS) such as WAAS. Japan, India, and Europe are building similar systems: EGNOS, the European Geostationary Navigation Overlay System; India’s GPS and Geo-Augmented Navigation (GAGAN) system; and Japan’s Multi-functional Transport Satellite (MT-SAT)-based Satellite Augmentation System (MSAS). The merging of these systems will create an expansive navigation capability similar to GPS, but with greater accuracy, availability, and integrity.

For users in the US, it just means WAAS. Overseas users have different systems for accomplishing the same objectives.

GBAS and GLS

March 15th, 2017

I had seen these terms before but I forgot what they meant. TL;DR, they are a new system of ground based augmentation that will improve navigation performance in the immediate vicinity of an airport. Currently only Newark and Houston-Hobby have the systems installed and the required equipment is installed on some Boeing aircraft flown by United Airlines.

Pilot Controller Glossary
GROUND BASED AUGMENTATION SYSTEM (GBAS) LANDING SYSTEM (GLS)- A type of precision IAP based on local augmentation of GNSS data using a single GBAS station to transmit locally corrected GNSS data, integrity parameters and approach information. This improves the accuracy of aircraft GNSS receivers’ signal in space, enabling the pilot to fly a precision approach with much greater flexibility, reliability and complexity. The GLS procedure is published on standard IAP charts, features the title GLS with the designated runway and minima as low as 200 feet DA. Future plans are expected to support Cat II and CAT III operations.

The FAA has a page describing the system.

Satellite Navigation – Ground Based Augmentation System (GBAS)
Ground-Based Augmentation System (GBAS) is a system that provides differential corrections and integrity monitoring of Global Navigation Satellite Systems (GNSS). GBAS provides navigation and precision approach service in the vicinity of the host airport (approximately a 23 nautical mile radius), broadcasting its differential correction message via a very high frequency (VHF) radio data link from a ground-based transmitter. GBAS yields the extremely high accuracy, availability, and integrity necessary for Category I, and eventually Category II, and III precision approaches. GBAS demonstrated accuracy is less than one meter in both the horizontal and vertical axis.

Notes from the Instrument Procedures Handbook – Departure Procedures

March 13th, 2017

FAA-H-8083-16 Instrument Procedures Handbook
Chapter 1 Departures

Instrument departure procedures are preplanned IFR procedures that provide obstruction clearance from the terminal area to the appropriate en route structure. Primarily, these procedures are designed to provide obstacle protection for departing aircraft. There are two types of Departure Procedures (DPs): Obstacle Departure Procedures (ODPs) and Standard Instrument Departures (SIDs).

If an aircraft may turn in any direction from a runway within the limits of the assessment area and remain clear of obstacles that runway passes what is called a diverse departure assessment, and no ODP is published. A diverse departure assessment ensures that a prescribed, expanding amount of required obstacle clearance (ROC) is achieved during the climb-out until the aircraft can obtain a minimum 1,000 feet ROC in non-mountainous areas or a minimum 2,000 feet ROC in mountainous areas. Unless specified otherwise, required obstacle clearance for all departures, including diverse, is based on the pilot crossing the departure end of the runway (DER) at least 35 feet above the DER elevation, climbing to 400 feet above the DER elevation before making the initial turn, and maintaining a minimum climb gradient of 200 feet per nautical mile (FPNM), unless required to level off by a crossing restriction until the minimum IFR altitude is reached.

All departure procedures are initially assessed for obstacle clearance based on a 40:1 Obstacle Clearance Surface (OCS). If no obstacles penetrate this 40:1 OCS, the standard 200 FPNM climb gradient provides a minimum of 48 FPNM of clearance above objects that do not penetrate the slope.

Low, Close-In Obstacles
Obstacles that are located within 1 NM of the DER and penetrate the 40:1 OCS are referred to as “low, close-in obstacles” and are also included in the TPP [Terminal Procedures Publication]. These obstacles are less than 200 feet above the DER elevation, within 1 NM of the runway end, and do not require increased takeoff minimums. The standard rate-of-climb to clear these obstacles would require a climb gradient greater than 200 FPNM for a very short distance, only until the aircraft was 200 feet above the DER. To eliminate publishing an excessive climb gradient, the obstacle above ground level (AGL)/ MSL height and location relative to the DER is noted in the Takeoff Minimums and (Obstacle) Departure Procedures section of a given TPP booklet.

Obstacle Departure Procedures (ODPs)
The term ODP is used to define procedures that simply provide obstacle clearance. ODPs are only used for obstruction clearance and do not include ATC related climb requirements. In fact, the primary emphasis of ODP design is to use the least restrictive route of flight to the en route structure or to facilitate a climb to an altitude that allows random (diverse) IFR flight, while attempting to accommodate typical departure routes.

ODPs are textual in nature. However, due to the complex nature of some procedures, a visual presentation may be given. If the ODP is charted graphically, the chart itself includes the word “Obstacle” in parentheses in the title. Additionally, all newly-developed RNAV ODPs are issued in graphical form.

Standard Instrument Departures (SIDs)
A SID is an ATC-requested and developed departure route, typically used in busy terminal areas. It is designed at the request of ATC in order to increase capacity of terminal airspace, effectively control the flow of traffic with minimal communication, and reduce environmental impact through noise abatement procedures. ATC clearance must be received prior to flying a SID.

If you cannot comply with a SID, if you do not possess the charted SID procedure, or if you simply do not wish to use SIDs, include the statement “NO SIDs” in the remarks section of your flight plan. Doing so notifies ATC that they cannot issue you a clearance containing a SID, but instead will clear you via your filed route to the extent possible, or via a Preferential Departure Route (PDR).

Transition Routes
Charted transition routes allow pilots to transition from the end of the basic SID to a location in the en route structure. Typically, transition routes fan out in various directions from the end of the basic SID to allow pilots to choose the transition route that takes them in the direction of intended departure. A transition route includes a course, a minimum altitude, and distances between fixes on the route.

To fly a SID, you must receive approval to do so in a clearance. In order to accept a clearance that includes a SID, you must have the charted SID procedure in your possession at the time of departure.

DPs are also categorized by equipment requirements as follows:
Non-RNAV DP—established for aircraft equipped with conventional avionics using ground-based NAVAIDs. These DPs may also be designed using dead reckoning navigation.

RNAV DP—established for aircraft equipped with RNAV avionics (e.g., GPS, VOR/DME, DME/DME). Automated vertical navigation is not required.

Radar DP—radar may be used for navigation guidance for SID design. Radar SIDs are established when ATC has a need to vector aircraft on departure to a particular ATS Route, NAVAID, or fix.

All public RNAV SIDs and graphic ODPs are RNAV 1. These procedures generally start with an initial RNAV or heading leg near the departure end runway. From a required navigation performance (RNP) standpoint, RNAV departure routes are designed with 1 or 2 NM performance standards as listed below. This means you as the pilot and your aircraft equipment must be able to maintain the aircraft within 1 or 2 NM either side of route centerline.

• RNAV 1 procedures require that the aircraft’s total system error remain bounded by ±1 NM for 95 percent of the total flight time.
• RNAV 2 requires a total system error of not more than 2 NM for 95 percent of the total flight time.

RNP is RNAV with on-board monitoring and alerting; RNP is also a statement of navigation performance necessary for operation within defined airspace. RNP-1 (in-lieu-of RNAV- 1) is used when a DP that contains a constant radius to a fix (RF) leg or when surveillance (radar) monitoring is not desired for when DME/DME/IRU is used. These procedures are annotated with a standard note: “RNP-1.”

For details on RNP refer to this answer by DeltaLima on Aviation StackExchange. But basically,

The RNP value alway gives the 95% accuracy, the 99.999% assurance (integrity) limit is always at twice that value. So RNP 0.3 means that the aircraft has to stay within 0.3 NM of the designed path centreline 95% of the time. And if it exceeds the 0.6 NM threshold, an alert will be raised with 99.999% certainty. RNP systems therefore require a system monitoring function.

Pilots are not authorized to fly a published RNAV or RNP procedure unless it is retrievable by the procedure name from the navigation database and conforms to the charted procedure. No other modification of database waypoints or creation of user-defined waypoints on published RNAV or RNP procedures is permitted, except to change altitude and/or airspeed waypoint constraints to comply with an ATC clearance/ instruction, or to insert a waypoint along the published route to assist in complying with an ATC instruction.

There are two types of waypoints currently in use: fly-by (FB) and fly-over (FO). A FB waypoint typically is used in a position at which a change in the course of procedure occurs. Charts represent them with four-pointed stars. This type of waypoint is designed to allow you to anticipate and begin your turn prior to reaching the waypoint, thus providing smoother transitions. Conversely, RNAV charts show a FO waypoint as a four-pointed star enclosed in a circle. This type of waypoint is used to denote a missed approach point, a missed approach holding point, or other specific points in space that must be flown over.

SID Altitudes
SID altitudes can be charted in four different ways. The first are mandatory altitudes, the second, minimum altitudes, the third, maximum altitudes and the fourth is a combination of minimum and maximum altitudes or also referred to as block altitudes. Below are examples of how each will be shown on a SID approach plate.

• Mandatory altitudes – 5500

• Minimum altitudes – 2300

• Maximum altitudes – 3300

• Combination of minimum and maximum –
7000
4600

Radar Departures
A radar departure is another option for departing an airport on an IFR flight. You might receive a radar departure if the airport does not have an established departure procedure, if you are unable to comply with a departure procedure, or if you request “No SIDs” as a part of your flight plan. Terrain and obstacle clearance remain your responsibility until the controller begins to provide navigational guidance in the form of radar vectors.

Visual Climb Over Airport (VCOA)
A visual climb over airport (VCOA) is a departure option for an IFR aircraft, operating in VMC equal to or greater than the specified visibility and ceiling, to visually conduct climbing turns over the airport to the published “climb-to” altitude from which to proceed with the instrument portion of the departure. [These are not very common. KTVL has one. VCOA: Rwy 18, Obtain ATC approval for climb in visual conditions when requesting IFR clearance. Remain within 3 NM, climb in visual conditions to cross South Lake Tahoe airport at or above 11100 MSL then intercept and proceed on SWR-127 to SWR VOR/DME. More details in this post.]

Notes from the Instrument Procedures Handbook – Departure Weather

March 13th, 2017

FAA-H-8083-16 Instrument Procedures Handbook
Chapter 1 Departures

Takeoff Minimums

Takeoff minimums are typically lower than published landing minimums, and ceiling requirements are only included if it is necessary to see and avoid obstacles in the departure area.

The FAA establishes takeoff minimums for every airport that has published Standard Instrument Approaches. These minimums are used by commercially operated aircraft, namely Part 121 and Part 135 operators.

FAA designated standard minimums: 1 statute mile (SM) visibility for single- and twin-engine aircraft, and 1⁄2 SM for helicopters and aircraft with more than two engines.

Aircraft operating under 14 CFR Part 91 are not required to comply with established takeoff minimums. Legally, a zero/ zero departure may be made, but it is never advisable.

If an airport has non-standard takeoff minimums, a Alternate Takeoff Minimums is placed in the notes sections of the instrument procedure chart. In the front of the TPP booklet, takeoff minimums are listed before the obstacle departure procedure.

Ceiling and Visibility Requirements
All takeoffs and departures have visibility minimums (some may have minimum ceiling requirements) incorporated into the procedure.

Visibility
Visibility is the ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night. Visibility is reported as statute miles, hundreds of feet, or meters.

Prevailing Visibility
Prevailing visibility is the greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle, which need not necessarily be continuous. Prevailing visibility is reported in statute miles or fractions of miles.

Runway Visibility Value (RVV)
Runway visibility value is the visibility determined for a particular runway by a transmissometer. A meter provides continuous indication of the visibility (reported in statute miles or fractions of miles) for the runway. RVV is used in lieu of prevailing visibility in determining minimums for a particular runway.

Tower Visibility
Tower visibility is the prevailing visibility determined from the airport traffic control tower at locations that also report the surface visibility.

Runway Visual Range (RVR)
Runway visual range is an instrumentally derived value, based on standard calibrations, that represents the horizontal distance a pilot sees down the runway from the approach end. RVR, in contrast to prevailing or runway visibility, is based on what a pilot in a moving aircraft should see looking down the runway.

Ceilings
Ceiling is the height above the earth’s surface of the lowest layer of clouds or obscuring phenomena that is reported as broken, overcast, or obscuration and not classified as thin or partial.

IFR Alternate Requirements
On AeroNav Products charts, standard alternate minimums are not published. If the airport has other than standard alternate minimums, they are listed in the front of the approach chart booklet.

For airplane 14 CFR Part 91 requirements, an alternate airport must be listed on IFR flight plans if the forecast weather at the destination airport, for at least 1 hour before and for 1 hour after the estimated time of arrival (ETA), the ceiling is less than 2,000 feet above the airport elevation, and the visibility is less than 3 SM.

For an airport to be used as an alternate, the forecast weather at that airport must meet certain qualifications at the ETA. Standard airplane alternate minimums for a precision approach are a 600-foot ceiling and a 2 SM visibility. For a non-precision approach, the minimums are an 800-foot ceiling and a 2 SM visibility.

Holding Patterns

March 12th, 2017

Someone asked why there are different speeds and leg times on holding patterns. I gave up on trying to figure out why the designers do what they do. However, here’s a guess on this one.


     Altitude (MSL)    Airspeed (KIAS)    Leg Time
     MHA - 6,000'           200           1 minute
     6,001' - 14,000’       230           1 minute 30 seconds
     14,001' and above      265           1 minute 30 seconds

If you are holding below 6,000′ you are most likely on an approach to an airport or holding at the missed approach point. By limiting speed to 200kts and legs to 1 minute the protected area is much smaller. Often you will also see a note on the chart limiting the distance from the holding fix. The designer can make the hold closer to the airport elevation which makes the approach easier for the pilot.

The purpose of the hold on an approach chart is for a course reversal or missed approach. On other forums, general aviation pilots have stated that they have never, or almost never, been given a hold for spacing when on an approach. I was given the option to hold once when on a practice approach but opted instead for vectors.

If you are holding above 6,000′ you are most likely not a Cessna 152—you are probably in a much faster airplane. So the protected space needs to be substantially larger. That’s why the airspeed is limited to 230 kts between 6,001′ – 14,000’ and legs are 1 minute 30 seconds.

Above 14,000′ you are probably an airliner or business plane that is holding for spacing purposes. The highest mountain peak in the continental US is 14,505′ and we know that in mountainous areas the MEA is 2,000′ above the highest obstacle. So a hold along an airway has 4 miles on the holding side already protected. And outside of California and Colorado there is plenty of room. ATC can have an aircraft hold without worrying about them hitting the ground. But limiting airspeed to 265 kts and making legs 1 minute 30 Seconds makes it easier to ensure that the airplane won’t hit anyone else.

Holds used to be much more common in the US airspace but the FAA computers do a much better job of estimating traffic and the implementation of ground stops and EDCTs has made them much less common than in the past. From what I have read on other blogs, they are mostly used for unanticipated weather delays.

ELT Battery Replacement

March 9th, 2017

§91.207 Emergency locator transmitters.

(c) Batteries used in the emergency locator transmitters required by
paragraphs (a) and (b) of this section must be replaced (or recharged,
if the batteries are rechargeable)—
  (1) When the transmitter has been in use for more than 1 cumulative
hour; or
  (2) When 50 percent of their useful life (or, for rechargeable
batteries, 50 percent of their useful life of charge) has expired, as
established by the transmitter manufacturer under its approval.

The battery replacement is preventive maintenance per Part 43 Appendix A(c) and may be owner-performed (and must be logged). The annual functional check per 91.207 requires an A&P and is normally performed at the same time as the annual inspection and normally documented in the annual inspection logbook entry, although it’s not actually part of an annual inspection per Part 43 Appendix D. Mike Busch

Getting information on how long they must transmit is surprisingly hard. Many of the technical documents cost money to access, e.g. DO-204A, Minimum Operational Performance Standards (MOPS) for 406 MHz Emergency Locator Transmitters (ELTs) so I can’t read them.

I found one reputable source for the lifetime once activated.

“Depends on a lot of factors. The design criteria is that they transmit for at least 48 hours at 0-degrees, some will transmit much longer if the weather is warm, the battery fresh, etc. Or they will transmit for less if it’s colder, if the battery hasn’t been replaced when it was supposed to, etc.” Richard A. De Castro -N6RCX NREMT SAR Tech

Flavors of FAA Approval for Certified Aircraft

March 8th, 2017

On one of the blogs I follow, a poster asked about installing a non-TSO’d part on an older aircraft. It is an interesting question, so I decided to write about it.

Certified aircraft meet either the rules of CAR 3 or more recently CFR 14 Part 23. This is called the Type Certificate. In general, you cannot add or remove anything from a certificated airplane without approval by the FAA. That approval comes in lots of flavors. (Note: I’m simplifying this. It gets really complicated.)

Type Certificate
You can replace any part with a part that is listed in the original type certificate. Those part numbers are found in the original Aircraft Flight Manual or the parts manual for the aircraft. Many of the parts are also covered by TSOs, PMAs, or Standard Parts as described below.

Technical Standards Orders
A TSO is a minimum performance standard for specified materials, parts, and appliances used on civil aircraft. When authorized to manufacture a material, part, or appliances to a TSO standard, this is referred to as TSO authorization. Receiving a TSO authorization is both design and production approval.

An altimeter is common to all aircraft and the FAA has issued TSO-C10b that tells manufacturers the standards that altimeters must meet. If it meets the standards, and the manufacturer hasn’t specified something different when it certified the airplane, then it can be installed on the aircraft by a licensed A&P. When he makes a logbook entry for it, it is legal to fly the airplane. You can buy non-TSO’d altimeters for much less than TSO’d ones, and they might even be “better” but you can only install them on experimental airplanes.

Parts Manufacturer Approval (PMA)
Is a combined design and production approval for modification and replacement articles. It allows a manufacturer to produce and sell these articles for installation on type certificated products.

This is another way you can replace parts on your airplane. These cover generic type items. Oil filters, spark plugs, tires, etc. It also covers things that are made by reference to the original manufacturers specifications. Things like muffler shrouds and engine mounts come to mind.

Standard Parts
The parts manual for an aircraft will refer to things like screws and gaskets by industry standard nomenclature. e.g. Cad Plated MS24694-S1 screws, MS24665 cotter pins.

You can replace the carpet in your plane with new carpet, provided it meets the flame resistant standards.

Often however, you can’t substitute a part from the hardware store that is as good or better than the original and you end up paying $150 for a 50 cent gasket. I once bought 25 feet of gasket for the landing gear doors from Cessna for $250. The exact same product is sold at Home Depot for $18. But it doesn’t have a PMA certificate.

Supplemental Type Certificates
A supplemental type certificate (STC) is a type certificate (TC) issued when an applicant has received FAA approval to modify an aeronautical product from its original design. The STC, which incorporates by reference the related TC, approves not only the modification but also how that modification affects the original design.

My airplane came with navigation and communication radios that we replaced with a Garmin GPS 430. Garmin conforms to TSO−C146() so we can use it as an approved primary navigation i.e. to fly en route, terminal, and WAAS approaches. There is an STC that details Limitations, Emergency Procedures, and Normal Procedures. As long as it was installed according to the STC we’re legal. That STC required adding pages to our Aircraft Flight Manual.

The autopilot on my plane was installed on the basis of an STC. This STC must be carried in the plane and there are a bunch of pages added to the AFM. STCs are filed with the FAA with a Form 337.

Some examples are: Ski holder for Cessna 182, Mirrors for checking if your wheels are down on Cessna 210, Gross weight increase for certain model Cessnas.

Owner Produced
This gets complicated, but a simple example would be if you lost an inspection plate. You could have a local machine shop cut out a new piece from the same gauge aluminum and use it on your plane. The A&P would make a logbook entry stating that they replaced the missing plate with an owner-produced plate.

AC 23-27 – Parts and Materials Substitution for Vintage Aircraft
This advisory circular (AC) provides guidance for substantiating parts or materials substitutions to maintain the safety of old or out-of-production general aviation (GA) aircraft, or other GA aircraft where the parts or materials are either difficult or impossible to obtain.

This gives the owner some flexibility in keeping our older aircraft flying.

Field Approval
If you want to make a modification to an aircraft that is not covered by any of the above, you can ask the local FSDO to approve it.

There was some discussion about whether LED landing lights were PMA’d or required a field approval. To be on the safe side, some people got field approval before installing them. Field approval is often used to install a TSO’d part on an aircraft that was not originally installed on. i.e. bigger brakes and wheels on a bush plane.

I think that covers everything. Let me know if I left out a category.

The original poster, who is not familiar with airplane maintenance, posted a follow-up question.

“Now what about aircraft certified before TSO standards were issued?”

If the part you want to replace has no TSO or PMA standard, then you could replace it with a part from another aircraft of the same type or the same part that is called out in the type certificate. For example, the Airplane Flight Manual that came with my Cherokee specifies a Harrison #C-8526250 Oil Cooler. If I can find the same oil cooler at a junkyard, I can install it—provided that it is in serviceable condition. Otherwise, I’d need to comply with one of the other items on the list.

In your altimeter example, there is a TSO for altimeters. Altimeters are one of the items required to be in an aircraft and working. Even if the TSO didn’t exist when the aircraft was manufactured, it does now, so you cannot go to Aircraft Spruce and buy a non-TSO’d altimeter and install it in the aircraft.

You can do an end-run around the TSO requirement. For example, Dynon has been making a poor-man’s glass-panel for experimental aircraft. Dynon’s EFIS-D10A. It displays all of the six-pack instruments. The EAA obtained an STC that allows you to replace the attitude indicator on many certificated airplanes. You buy the EFIS from a vendor and pay EAA $100 and you can replace your TSO’d attitude indicator.

If you are going to replace a part on a certificated airplane, you need some legal basis for doing so. TSO’s, PMA’d, and Original Equipment Manufacture (OEM) parts meet the legal test. STCs are slightly more difficult to use, but they also easily meet the test. The other items on the list require judgement calls by your A&P or the FSDO.

Notes on the Instrument Procedures Handbook – Approaches

March 7th, 2017

FAA-H-8083-16 Instrument Procedures Handbook
Chapter 4 Approaches

Primary NAVAID
Most conventional approach procedures are built around a primary final approach NAVAID; others, such as RNAV (GPS) approaches, are not. If a primary NAVAID exists for an approach, it should be included in the IAP briefing, set into the appropriate backup or active navigation radio, and positively identified at some point prior to being used for course guidance.

Area Navigation Courses
Approach waypoints, except for the missed approach waypoint (MAWP) and the missed approach holding waypoint (MAHWP), are normally FlyBy WPs.

Altitudes
Prescribed altitudes may be depicted in four different configurations: minimum, maximum, recommended, and mandatory.

Minimum Safe Altitude
Minimum safe altitudes (MSAs) are published for emergency use on IAP charts. For conventional navigation systems, the MSA is normally based on the primary omnidirectional facility on which the IAP is predicated.

For RNAV approaches, the MSA is based on either the runway waypoint (RWY WP), the MAWP for straight-in approaches, or the airport waypoint (APT WP) for circling only approaches. For RNAV (GPS) approaches with a terminal arrival area (TAA), the MSA is based on the IAF WP.

MSAs provide 1,000 feet clearance over all obstructions but do not necessarily assure acceptable navigation signal coverage.

Final Approach Fix Altitude
Another important altitude that should be briefed during an IAP briefing is the FAF altitude, designated by the cross on a non-precision approach, and the lightning bolt symbol designating the glideslope intercept altitude on a precision approach. Adherence and cross-check of this altitude can have a direct effect on the success and safety of an approach.

Minimum Descent Altitude (MDA), Decision Altitude (DA), And Decision Height (DH)

MDA—the lowest altitude, expressed in feet MSL, to which descent is authorized on final approach or during circle-to-land maneuvering in execution of a standard instrument approach procedure (SIAP) where no electronic glideslope is provided.

DA—a specified altitude in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.

DH—with respect to the operation of aircraft, means the height at which a decision must be made during an ILS, MLS, or PAR IAP to either continue the approach or to execute a missed approach.

CAT II and III approach DHs are referenced to AGL and measured with a radio altimeter.

Vertical Navigation
Modern RNAV avionics can display an electronic vertical path that provides a constant-rate descent to minimums.

The pilots, airplane, and operator must be approved to use advisory VNAV inside the FAF on an instrument approach.

VNAV information appears on selected conventional nonprecision, GPS, and RNAV approaches (see “Types of Approaches” later in this chapter). It normally consists of two fixes (the FAF and the landing runway threshold), a FAF crossing altitude, a vertical descent angle (VDA), and may provide a visual descent point ( VDP).

VISUAL DESCENT POINT− A defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the approach threshold of that runway, or approach lights, or other markings identifiable with the approach end of that runway are clearly visible to the pilot. (Pilot Controller Glossary) [Note: This point does not show up as a named waypoint on GPS Navigation devices or ForeFlight. It is shown on some RNAV approaches as a distance to the threshold and on some approaches with DME as a DME distance. More info at this post.]

Wide Area Augmentation System
WAAS enabled vertically guided approach procedures are called LPV, which stands for “localizer performance with vertical guidance,” and provide ILS equivalent approach minimums as low as 200 feet at qualifying airports.

RNAV (GPS) approach charts presently can have up to four lines of approach minimums: LPV, LNAV/VNAV, LNAV, and Circling.

GPS receivers (non-WAAS) can fly to the LNAV MDA.

GPS and FMS (with approach-certified barometric vertical navigation, or Baro-VNAV) can fly to the LNAV/VNAV MDA.

WAAS-LPV avionics can fly an LPV approach

If for some reason the WAAS service becomes unavailable, all GPS or WAAS equipped aircraft can revert to the LNAV MDA and land safely using GPS only, which is available nearly 100 percent of the time.

LNAV/VNAV identifies APV minimums developed to accommodate an RNAV IAP with vertical guidance, usually provided by approach certified Baro-VNAV, but with vertical and lateral integrity limits larger than a precision approach or LPV. Airplanes that are commonly approved in these types of operations include Boeing 737NG, 767, and 777, as well as the Airbus A300 series.

Ground-Based Augmentation System (GBAS)
GBAS is comprised of ground equipment and avionics. The ground equipment includes four reference receivers, a GBAS ground facility, and a VHF data broadcast transmitter. This ground equipment is complemented by GBAS avionics installed on the aircraft. Signals from GPS satellites are received by the GBAS GPS reference receivers (four receivers for each GBAS) at the GBAS equipped airport. The reference receivers calculate their position using GPS. The GPS reference receivers and GBAS ground facility work together to measure errors in GPS provided position.

The GBAS ground facility produces a GBAS correction message based on the difference between actual and GPS calculated position. Included in this message is suitable integrity parameters and approach path information. This GBAS correction message is then sent to a VHF data broadcast (VDB) transmitter. The VDB broadcasts the GBAS signal throughout the GBAS coverage area to avionics in GBAS equipped aircraft. GBAS provides its service to a local area (approximately a 20–30 mile radius). The signal coverage is designed support the aircraft’s transition from en route airspace into and throughout the terminal area airspace.

Approaches are named GLS in the TPP. GLS RWY 4L at Newark is an example.

Required Navigation Performance (RNP)
To attain the benefits of RNP approach procedures, a key component is curved flight tracks. Constant radius turns around a fix are called “radius-to-fix legs (RF legs).” These turns, which are encoded into the navigation database, allow the aircraft to avoid critical areas of terrain or conflicting airspace while preserving positional accuracy by maintaining precise, positive course guidance along the curved track. The introduction of RF legs into the design of terminal RNAV procedures results in improved use of airspace and allows procedures to be developed to and from runways that are otherwise limited to traditional linear flight paths or, in some cases, not served by an IFR procedure at all. Navigation systems with RF capability are a prerequisite to flying a procedure that includes an RF leg. Garmin GTN-series avionics should be able to fly the RF legs used as transitions/feeder routes on those approaches

Baro-VNAV
Baro-VNAV is an RNAV system function that uses barometric altitude information from the aircraft’s altimeter to compute and present a vertical guidance path to the pilot. The specified vertical path is computed as a geometric path, typically computed between two waypoints or an angle based computation from a single waypoint. Operational approval must also be obtained for Baro−VNAV systems to operate to the LNAV/VNAV minimums. Baro−VNAV may not be authorized on some approaches due to other factors, such as no local altimeter source being available. Baro−VNAV is not authorized on LPV procedures.

Hot and Cold Temperature Limitations
A minimum and maximum temperature limitation is published on procedures that authorize Baro−VNAV operation.

e.g. RNAV (GPS) RWY 11 KSPB Note: For uncompensated Baro VNAV systems, LNAV/VNAV NA below -15°C or above 42°C.

Transition to a Visual Approach
The visibility published on an approach chart is dependent on many variables, including the height above touchdown for straight-in approaches or height above airport elevation for circling approaches. Other factors include the approach light system coverage, and type of approach procedure, such as precision, non-precision, circling or straight-in. Another factor determining the minimum visibility is the penetration of the 34:1 and 20:1 surfaces. These surfaces are inclined planes that begin 200 feet out from the runway and extend outward to the DA point (for approaches with vertical guidance), the VDP location (for non-precision approaches) and 10,000 feet for an evaluation to a circling runway. If there is a penetration of the 34:1 surface, the published visibility can be no lower than three-fourths SM. If there is penetration of the 20:1 surface, the published visibility can be no lower than 1 SM with a note prohibiting approaches to the affected runway at night (both straight-in and circling).

For RNAV approaches only, the presence of a grey shaded line from the MDA to the runway symbol in the profile view is an indication that the visual segment below the MDA is clear of obstructions on the 34:1 slope. Absence of the gray shaded area indicates the 34:1 OCS is not free of obstructions.

RNAV Shaded example

Missed Approach
Many reasons exist for executing a missed approach. The primary reasons, of course, are that the required flight visibility prescribed in the IAP being used does not exist.

In addition, according to 14 CFR Part 91, the aircraft must continuously be in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under Part 121 or 135, unless that descent rate allows touchdown to occur within the TDZ of the runway of intended landing.

A clearance for an instrument approach procedure includes a clearance to fly the published missed approach procedure, unless otherwise instructed by ATC. Once descent below the DA, DH, or MDA is begun, a missed approach must be executed if the required visibility is lost or the runway environment is no longer visible, unless the loss of sight of the runway is a result of normal banking of the aircraft during a circling approach.

Course Reversal
On U.S. Government charts, a barbed arrow indicates the maneuvering side of the outbound course on which the procedure turn is made. Headings are provided for course reversal using the 45° type procedure turn. However, the point at which the turn may be commenced and the type and rate of turn is left to the discretion of the pilot (limited by the charted remain within XX NM distance). Some of the options are the 45° procedure turn, the racetrack pattern, the teardrop procedure turn, or the 80° procedure turn, or the 80° 260° course reversal. Racetrack entries should be conducted on the maneuvering side where the majority of protected airspace resides.

Some procedure turns are specified by procedural track. These turns must be flown exactly as depicted.

Descent to the PT completion altitude from the PT fix altitude (when one has been published or assigned by ATC) must not begin until crossing over the PT fix or abeam and proceeding outbound.

A holding pattern in lieu of procedure turn may be specified for course reversal in some procedures. In such cases, the holding pattern is established over an intermediate fix or a FAF. The holding pattern distance or time specified in the profile view must be observed. If pilots elect to make additional circuits to lose excessive altitude or to become better established on course, it is their responsibility to so advise ATC upon receipt of their approach clearance.

Initial Approach Segment
The purposes of the initial approach segment are to provide a method for aligning the aircraft with the intermediate or final approach segment and to permit descent during the alignment. This is accomplished by using a DME arc, a course reversal, such as a procedure turn or holding pattern, or by following a terminal route that intersects the final approach course. The initial approach segment begins at an IAF and usually ends where it joins the intermediate approach segment or at an IF.

Many RNAV approaches make use of a dual-purpose IF/IAF associated with a hold-in-lieu-PT (HILPT) anchored at the Intermediate Fix. The HILPT forms the Initial Approach Segment when course reversal is required.

Intermediate Approach Segment
The intermediate segment is designed primarily to position the aircraft for the final descent to the airport. Like the feeder route and initial approach segment, the chart depiction of the intermediate segment provides course, distance, and minimum altitude information.

In some cases, an IF is not shown on an approach chart. In this situation, the intermediate segment begins at a point where you are proceeding inbound to the FAF, are properly aligned with the final approach course, and are located within the prescribed distance prior to the FAF.

Final Approach Segment
The final approach segment for an approach with vertical guidance or a precision approach begins where the glideslope intercepts the minimum glideslope intercept altitude shown on the approach chart.

For a non-precision approach, the final approach segment begins either at a designated FAF, which is depicted as a cross on the profile view, or at the point where the aircraft is established inbound on the final approach course.

There are three types of procedures based on the final approach course guidance:
Precision approach (PA)—an instrument approach based on a navigation system that provides course and glidepath deviation information meeting precision standards of ICAO Annex 10. For example, PAR, ILS, and GLS are precision approaches.

Approach with vertical guidance (APV) —an instrument approach based on a navigation system that is not required to meet the precision approach standards of ICAO Annex 10, but provides course and glidepath deviation information. For example, Baro-VNAV, LDA with glidepath, LNAV/VNAV and LPV are APV approaches.

Non-precision approach (NPA)—an instrument approach based on a navigation system that provides course deviation information but no glidepath deviation information. For example, VOR, TACAN, LNAV, NDB, LOC, and ASR approaches are examples of NPA procedures.

Missed Approach Segment
The missed approach segment begins at the MAP and ends at a point or fix where an initial or en route segment begins.

Precision or an APV approach, the MAP occurs at the DA or DH on the glideslope.

For non-precision approaches, the MAP is either a fix, NAVAID, or after a specified period of time has elapsed after crossing the FAF.

Vectors To Final Approach Course
The approach gate is an imaginary point used within ATC as a basis for vectoring aircraft to the final approach course. The gate is established along the final approach course one mile from the FAF on the side away from the airport and is no closer than 5 NM from the landing threshold.

The controller should always assign an altitude to maintain until the aircraft is established on a segment of a published route or IAP.

Visual and Contact Approaches
To expedite traffic, ATC may clear pilots for a visual approach in lieu of the published approach procedure if flight conditions permit. Requesting a contact approach may be advantageous since it requires less time than the published IAP and provides separation from IFR and special visual flight rules (SVFR) traffic. A contact or visual approach may be used in lieu of conducting a SIAP, and both allow the flight to continue as an IFR flight to landing while increasing the efficiency of the arrival.

For a visual approach clearance, the controller must verify that pilots have the airport, or a preceding aircraft that they are to follow, in sight. May be assigned by ATC. It is authorized when the ceiling is reported or expected to be at least 1,000 feet AGL and the visibility is at least 3 SM.

Contact Approaches
Pilots can request a contact approach, which is then authorized by the controller. A contact approach cannot be initiated by ATC. The airport must have a SIAP the reported ground visibility is at least 1 SM, and pilots are able to remain clear of clouds with at least one statute mile flight visibility throughout the approach.

Terminal Arrival Areas
TAAs are the method by which aircraft equipped with a FMS and/or GPS are transitioned from the RNAV en route structure to the terminal area with minimal ATC interaction.

ILS Approach Categories
There are three general classifications of ILS approaches: CAT I, CAT II, and CAT III (autoland). The basic ILS approach is a CAT I approach and requires only that pilots be instrument rated and current, and that the aircraft be equipped appropriately. CAT II and CAT III ILS approaches typically have lower minimums and require special certification for operators, pilots, aircraft, and airborne/ground equipment. Because of the complexity and high cost of the equipment, CAT III ILS approaches are used primarily in air carrier and military operations.

Notes on the Instrument Procedures Handbook – Arrivals

March 6th, 2017

FAA-H-8083-16 Instrument Procedures Handbook
Chapter 3 Arrivals

Descending From the En Route Altitude
Making the transition from cruise flight to the beginning of an instrument approach procedure sometimes requires arriving at a given waypoint at an assigned altitude. When this requirement is prescribed by a published arrival procedure or issued by ATC, it is called a crossing restriction.

Descend at the optimum rate for the aircraft being flown until 1,000 feet above the assigned altitude, then descend at a rate between 500 and 1,500 fpm to the assigned altitude.

When ATC issues a clearance to descend at pilot’s discretion, pilots may begin the descent whenever they choose and at any rate of their choosing. Pilots are also authorized to level off, temporarily, at any intermediate altitude during the descent. However, once the aircraft leaves an altitude, it may not return to that altitude.

Sterile Flight Deck Rules
14 CFR Part 121, section 121.542 and Part 135, section 135.100, Flight Crewmember Duties, commonly referred to as “sterile flight deck rules”. The provisions in this rule can help pilots, operating under any regulations, to avoid altitude and course deviations during arrival. In part, it states: (a) No certificate holder should require, nor may any flight crewmember perform, any duties during a critical phase of flight except those duties required for the safe operation of the aircraft.
b) No flight crewmember may engage in, nor may any pilot in command permit, any activity during a critical phase of flight that could distract any flight crewmember from the performance of his or her duties or which could interfere in any way with the proper conduct of those duties.

Standard Terminal Arrival Routes (STARs)
STARs start at the en route structure but do not make it down to the pavement; they end at a fix or NAVAID designated by ATC, where radar vectors commonly take over.

The STAR and approach procedure should connect to one another in such a way as to maintain the overall descent and deceleration profiles. This often results in a seamless transition between the en route, arrival, and approach phases of flight, and serves as a preferred route into high volume terminal areas.

STAR procedures typically include a standardized descent gradient at and above 10,000 feet MSL of 318 feet per nautical mile (FPNM), or 3 degrees. Below 10,000 feet MSL, the maximum descent rate is 330 FPNM, or approximately 3.1 degrees.

Use of a STAR requires pilot possession of at least the approved chart. RNAV STARs must be retrievable by the procedure name from the aircraft database and conform to charted procedure.

A STAR is simply a published routing; it does not have the force of a clearance until issued specifically by ATC.

During arrivals, when cleared for an instrument approach, maintain the last assigned altitude until established on a published segment of the approach or on a segment of a published route. If no altitude is assigned with the approach clearance and the aircraft is already on a published segment, the pilot can descend to its minimum altitude for that segment of the approach.

14 CFR Part 91, section 91.117 still apply during speed adjustments. It is the pilot’s responsibility to advise ATC if an assigned speed adjustment would cause an exceedence of these limits. For operations in Class C or D airspace at or below 2,500 feet above ground level (AGL), within 4 NM of the primary airport, ATC has the authority to approve a faster speed than those prescribed.

It is normal to level off at 2,500 feet above airport elevation to slow to the 200 KIAS limit that applies within the surface limits of Class C or D airspace. Controllers anticipate this action and plan accordingly.

Holding Patterns
If aircraft reach a clearance limit before receiving a further clearance from ATC, a holding pattern is required at the last assigned altitude.

DME and IFR-certified GPS equipment offer some additional options for holding. Rather than being based on time, the leg lengths for DME/GPS holding patterns are based on distances in nautical miles. These patterns use the same entry and holding procedures as conventional holding patterns. The controller or the instrument approach procedure chart specifies the length of the outbound leg. The end of the outbound leg is determined by the DME or the along track distance (ATD) readout.

When flying published GPS overlay or standalone procedures with distance specified, the holding fix is a waypoint in the database and the end of the outbound leg is determined by the ATD (along track distance).

Approach Clearance
The approach clearance provides guidance to a position from where the pilot can execute the approach. It is also a clearance to fly that approach.

When a vector takes the aircraft across the final approach course, pilots are informed by ATC and the reason for the action is stated. In the event that ATC is not able to inform the aircraft, the pilot is not expected to turn inbound on the final approach course unless an approach clearance has been issued.

The following ATC arrival instructions are issued to an IFR aircraft before it reaches the approach gate:
1. Position relative to a fix on the final approach course. If none is portrayed on the controller’s radar display or if none is prescribed in the instrument approach procedure, ATC issues position information relative to the airport or relative to the NAVAID that provides final approach guidance.
2. Vector to intercept the final approach course if required.
3. Approach clearance except when conducting a radar approach. ATC issues the approach clearance only after the aircraft is established on a segment of a published route or instrument approach procedure.

Sometimes IAPs have no initial segment and require vectors. “RADAR REQUIRED” is charted in the plan view.

Notes from the Instrument Procedures Handbook – En Route

March 6th, 2017

FAA-H-8083-16 Instrument Procedures Handbook
Chapter 2 En Route

The en route phase of flight is defined as that segment of flight from the termination point of a departure procedure to the origination point of an arrival procedure.

En Route Airspace Structure

Low Altitude Victor Airways:
  Use Navaids
  1,200′ AGL – 18,000′ MSL

High Altitude Jet Routes
  18,000′ – FL450

Above FL450
  Random operations allowed

Air Route Traffic Control Center
A facility established to provide air traffic control (ATC) service to aircraft operating on IFR flight plans within controlled airspace, principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft.

Aircraft are separated by the following criteria:
• Laterally—
  5 miles
• Vertically—
  1,000 feet (if the aircraft is below FL290, or between FL290 and FL410 for RVSM compliant aircraft)
  2,000 feet (if the aircraft is at FL290 or above)

High Altitude Area Navigation Routing
Special high altitude routes allow pilots routing options for flight within the initial high altitude routing (HAR) Phase I expansion airspace. Pilots are able to fly user-preferred routes, referred to as non-restrictive routing (NRR), between specific fixes described by pitch (entry into) and catch (exit out of) fixes in the HAR airspace. Pitch points indicate an end of departure procedures, preferred IFR routings, or other established routing programs where a flight can begin a segment of NRR. The catch point indicates where a flight ends a segment of NRR and joins published arrival procedures, preferred IFR routing, or other established routing programs.

Above FL 350 in fourteen of the western and soutern ARTCCs
Chart Supplement has pitch and catch points.

Catch Point

RNAV routes – Q Routes
Published as preferred IFR routes.

Preferred IFR Routes
Preferred IFR routes are established between busier airports to increase system efficiency and capacity.

Published in the Chart Supplement for low and high stratum.

Preferred Route

Tower En Route Control
An ATC program available to pilots that provides a service to aircraft proceeding to and from metropolitan areas.
Fly an IFR flight without leaving approach control airspace.

Tower Enroute Control

Altitudes and routes depend on aircraft classification: J-Jet, M—Turbo-Props, P—Non-Jet cruise speed > 190 kts, Q—Non-Jet cruise speed < 190 kts.

Primary and Secondary En Route Obstacle Clearance Areas
The primary obstacle clearance area has a protected width of 8 NM with 4 NM on each side of the centerline. The primary area has widths of route protection based upon system accuracy of a ±4.5° angle from the NAVAID. These 4.5° lines extend out from the NAVAID and intersect the boundaries of the primary area at a point approximately 51 NM from the NAVAID. Ideally, the 51 NM point is where pilots would change over from navigating away from the facility, to navigating toward the next facility, although this ideal is rarely achieved.

If the distance from the NAVAID to the change-over point (COP) is more than 51 NM, the outer boundary of the primary area extends beyond the 4 NM width.

Primary Obstacle Area

Secondary Obstacle Area

Secondary Obstacle Area has 500′ obstacle clearance.

Direct Route Flights
Direct route flights are flights that are not flown on the radials or courses of established airways or routes. Direct route flights must be defined by indicating the radio fixes over which the flight passes. Fixes selected to define the route should be those over which the position of the aircraft can be accurately determined. Such fixes automatically become compulsory reporting points for the flight, unless advised otherwise by ATC.

Operational Service Volume Limits

1. Operations above FL 450—use NAVAIDs not more than 200 NM apart. These aids are depicted on en route high altitude charts.
2. Operation off established routes from 18,000 feet MSL to FL 450—use NAVAIDs not more than 260 NM apart. These aids are depicted on en route high altitude charts.
3. Operation off established airways below 18,000 feet MSL—use NAVAIDs not more than 80 NM apart. These aids are depicted on en route low altitude charts.
4. Operation off established airways between 14,500 feet MSL and 17,999 feet MSL in the conterminous United States—(H) facilities not more than 200 NM apart may be used.

Published RNAV Routes
Published RNAV routes are fixed, permanent routes that can be flight planned and flown by aircraft with RNAV capability.

OROCA – Off-Route Obstruction Clearance Altitude
An OROCA is an off-route altitude that provides obstruction clearance with a 1,000 foot buffer in non-mountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the United States. This altitude may not provide signal coverage from ground-based NAVAIDs, ATC radar, or communications coverage.

OROCAs depicted on en route charts do not provide the pilot with an acceptable altitude for terrain and obstruction clearance for the purposes of off-route, random RNAV direct flights in either controlled or uncontrolled airspace.

When accepting a clearance below the MEA, MIA, MVA, or the OROCA, you are responsible for your own terrain/ obstruction clearance until reaching the MEA, MIA, or MVA.

When you plan a random RNAV route, I would suggest you don’t restrict yourself to just the IFR enroute charts. I also look at sectional charts. They also depict a Maximum Elevation Figure (MEF) which may be used for altitude planning, but its dimensions are 30 minutes of latitude and longitude whereas the OROCA altitude covers an area of 1 degree of latitude and longitude, so there are 4 times the detail. If you use the MEF, remember that you have to add 1000 feet or 2000 feet (mountainous) to get to an equivalent to the OROCA, as the MEF only has a buffer of at most a few hundred feet and it depicts the MSL altitude of the obstacle or terrain. John D. Collins

Navigational Gaps
A navigational course guidance gap, referred to as an MEA gap, describes a distance along an airway or route segment where a gap in navigational signal coverage exists. The navigational gap may not exceed a specific distance that varies directly with altitude, from 0 NM at sea level to 65 NM at 45,000 feet MSL and not more than one gap may exist in the airspace structure for the airway or route segment.

Computer Navigation Performance
A point used for the purpose of defining the navigation track for an airborne computer system (i.e., GPS or FMS) is called a Computer Navigation Fix (CNF). CNFs include unnamed DME fixes, beginning and ending points of DME arcs, and sensor final approach fixes (FAFs) on some GPS overlay approaches.

A CNF name is enclosed in parenthesis, e.g., (MABEE) and is placed next to the CNF it defines. They are being replaced with fixes that start with CF.

IFR En Route Altitudes

Minimum En Route Altitude (MEA)
The MEA is the lowest published altitude between radio fixes that assures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes.

Minimum Crossing Altitude (MCA)
The standard for determining the MCA is based upon the following climb gradients and is computed from the flight altitude:
• Sea level through 5,000 feet MSL—150 feet per NM
• 5000 feet through 10,000 feet MSL—120 feet per NM
• 10,000 feet MSL and over—100 feet per NM

Minimum Reception Altitude (MRA)
The minimum altitude the navigation signal can be received for the route and for off-course NAVAID facilities that determine a fix. [Fixes on the chart have a flag with an R in it.]

Maximum Authorized Altitude (MAA)
An MAA is a published altitude representing the maximum usable altitude or flight level for an airspace structure or route segment. [Not very common. Used in high density areas like New York to keep traffic below arrivals and departures. e.g MAA-10000 on V213 between ARD and TEB.]

Minimum Obstruction Clearance Altitude (MOCA)
The MOCA is the lowest published altitude in effect between fixes on VOR airways, off-airway routes, or route segments that meets obstacle clearance requirements for the entire route segment. This altitude also assures acceptable navigational signal coverage only within 22 NM of a VOR. [Indicated on the chart with an asterisk preceeding the altitude e.g. *5800 between PMD VOR and VICKY waypoint.]

Minimum Turning Altitude (MTA)
Minimum turning altitude (MTA) is a charted altitude providing vertical and lateral obstruction clearance based on turn criteria over certain fixes, NAVAIDs, waypoints, and on charted route segments. [See this post for details.]

Minimum IFR Altitude (MIA)
The MIA for operations is prescribed in 14 CFR Part 91, 95 or 97.

Minimum Vectoring Altitudes (MVA)
MVAs are established for use by ATC when radar ATC is exercised. The MVA provides 1,000 feet of clearance above the highest obstacle in non-mountainous areas and 2,000 feet above the highest obstacle in designated mountainous areas.

Reduced Vertical Separation Minimums (RSVM)
RVSM is a term used to describe the reduction of the standard vertical separation required between aircraft flying at levels between FL 290 (29,000 feet) and FL 410 (41,000 feet) from 2,000 feet to 1,000 feet.

Cruise Clearance
The term “cruise” may be used instead of “maintain” to assign a block of airspace to an aircraft. The block extends from the minimum IFR altitude up to and including the altitude that is specified in the cruise clearance.

Altitude Above Ground (QFE)
A local altimeter setting equivalent to the barometric pressure measured at an airport altimeter datum, usually signifying the approach end of the runway is in use. At the airport altimeter datum, an altimeter set to QFE indicates zero altitude. If required to use QFE altimetry, altimeters are set to QFE while operating at or below the transition altitude and below the transition level. On the airport, the altimeter will read “0” feet.

Barometric Pressure for Standard Altimeter Setting (QNE)
Use the altimeter setting (en route) at or above the transition altitude (FL 180 in the United States). The altimeter setting is always 29.92 inches of mercury/1013.2 hPa for a QNE altitude.

Barometric Pressure for Local Altimeter Setting (QNH)
A local altimeter setting equivalent to the barometric pressure measured at an airport altimeter datum and corrected to sea level pressure. At the airport altimeter datum, an altimeter set to QNH indicates airport elevation above mean sea level (MSL). Altimeters are set to QNH while operating at and below the transition altitude and below the transition level.

En Route Reporting Procedures
Non-Radar Position Reports
All compulsory reporting points.

Position Report Items
Position reports should include the following items:
1. Aircraft identification
2. Position
3. Time
4. Altitude or flight level (include actual altitude or flight level when operating on a clearance specifying VFR-on-top)
5. Type of flight plan (not required in IFR position reports made directly to ARTCCs or approach control)
6. ETA and name of next reporting point
7. The name only of the next succeeding reporting point along the route of flight
8. Pertinent remarks

Additional Reports
The following reports should be made at all times to ATC or FSS facilities without a specific ATC request:

  • When vacating any previously assigned altitude or flight level for a newly assigned altitude or flight level.
  • When an altitude change is made if operating on a clearance specifying VFR-on-top.
  • When unable to climb/descend at a rate of a least 500 feet per minute (fpm).
  • When approach has been missed. (Request clearance for specific action (i.e., to alternative airport, another approach).
  • Change in the average true airspeed (at cruising altitude) when it varies by 5 percent or 10 knots (whichever is greater) from that filed in the flight plan.
  • The time and altitude or flight level upon reaching a holding fix or point to which cleared.
  • When leaving any assigned holding fix or point.
  • Any loss, in controlled airspace, of VOR, TACAN, ADF, low frequency navigation receiver capability, GPS anomalies while using installed IFR-certified GPS/GNSS receivers, complete or partial loss of ILS receiver capability or impairment of air/ground communications capability. Reports should include aircraft identification, equipment affected, degree to which the capability to operate under IFR in the ATC system is impaired, and the nature and extent of assistance desired from ATC.
  • Any information relating to the safety of flight.

Communication Failure
If the radio fails while operating on an IFR clearance, but in VFR conditions, or if encountering VFR conditions at any time after the failure, continue the flight under VFR conditions, if possible, and land as soon as practicable. The requirement to land as soon as practicable should not be construed to mean as soon as possible.

Route
If pilots must continue their flight under IFR after experiencing two-way radio communication failure, they should fly one of the following routes:
• The route assigned by ATC in the last clearance received.
• If being radar vectored, the direct route from the point of radio failure to the fix, route, or airway specified in the radar vector clearance.
• In the absence of an assigned route, the route ATC has advised to expect in a further clearance.
• In the absence of an assigned or expected route, the route led in the flight plan.

Altitude
• The altitude or flight level assigned in the last ATC clearance.
• The minimum altitude or flight level for IFR operations.
• The altitude or flight level ATC has advised to expect in a further clearance.

Climbing and Descending En Route
When ATC issues a clearance or instruction, pilots are expected to execute its provisions upon receipt. In some cases, ATC includes words that modify their expectation. For example, the word “immediately” in a clearance or instruction is used to impress urgency to avoid an imminent situation, and expeditious compliance is expected and necessary for safety.

Once you vacate an altitude, you may not return to that altitude.

Climb at an optimum rate consistent with the operating characteristics of the aircraft to 1,000 feet below the assigned altitude, and then attempt to climb at a rate of between 500 and 1,500 fpm until the assigned altitude is reached. If at any time the pilot is unable to climb at a rate of at least 500 fpm, advise ATC. If it is necessary to level off at an intermediate altitude during climb, advise ATC.

Controllers anticipate and plan that the pilot may level off at 10,000 feet MSL on descent to comply with the 14 CFR Part 91 indicated airspeed limit of 250 knots.

En Route Holding Procedures
For level holding, a minimum of 1,000 feet obstacle clearance is provided throughout the primary area. In the secondary area, 500 feet of obstacle clearance is provided at the inner edge, tapering to zero feet at the outer edge

The holding instructions include the direction from the fix, name of the fix, course, leg length, if appropriate, direction of turns (if left turns are required), and the EFC time.

Maximum holding speed
MHA – 6,000′ MSL 200 kts IAS
6,001′- 14,000′ MSL 230 kts
14,001’+ 265 kts

Mountain Flying

March 5th, 2017

While I have flown over the Sierras and Cascades a bunch of times, I have only landed at a few high altitude airports in the summer time. When I took off from Lake Tahoe and Jackson Hole I had an experienced mountain flyer with me and was flying a normally aspirated Cessna 182. We followed the techniques in this video and takeoff was interesting. It was fun to catch a mountain wave on the way out of Tahoe and gain quite a bit of altitude in a short time. Taking off from Durango, Colorado in a turbocharged Cessna 210 was not much different from taking off from my near sea-level home field. Just a longer takeoff roll.

Understanding VFR Charts

March 3rd, 2017

He covers the charts in great detail and includes a couple of things that I never noticed. Like, the little clumps of grass-like icons that are the Everglades swamp. There is also a notation on the chart for “numerous small lakes” in the area. Also good coverage of RCOs and communicating with ATC Radio.

Special Use Airspace

Localizer or VOR approaches with GPS

March 1st, 2017

AIM Effective: May 26, 2016. This change allows for the use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure (IAP) based on a VOR, TACAN, or NDB signal. The underlying NAVAID must be operational and monitored for the final segment course alignment.

1−1−18. Wide Area Augmentation System (WAAS)

1. Use of a suitable RNAV system as a Substitute Means of Navigation when a Very−High Frequency (VHF) Omni−directional Range (VOR), Distance Measuring Equipment (DME), Tactical Air Navigation (TACAN), VOR/TACAN (VORTAC), VOR/DME, Non−directional Beacon (NDB), or compass locator facility including locator outer marker and locator middle marker is out−of−service (that is, the navigation aid (NAVAID) information is not available); an aircraft is not equipped with an Automatic Direction Finder (ADF) or DME; or the installed ADF or DME on an aircraft is not operational. For example, if equipped with a suitable RNAV system, a pilot may hold over an out−of− service NDB.

2. Use of a suitable RNAV system as an Alternate Means of Navigation when a VOR, DME, VORTAC, VOR/DME, TACAN, NDB, or compass locator facility including locator outer marker and locator middle marker is operational and the respective aircraft is equipped with operational navigation equipment that is compatible with conventional navaids. For example, if equipped with a suitable RNAV system, a pilot may fly a procedure or route based on operational VOR using that RNAV system without monitoring the VOR.

You need to dig into the AIM to find out what they mean by “suitable RNAV system”. “the following systems qualify as a suitable RNAV system: 1. An RNAV system with TSO−C129/−C145/−C146 equipment, installed in accordance with AC 20−138,… and 2. An RNAV system with DME/DME/IRU inputs that is compliant with the equipment provisions of AC 90−100A” For most people, that means certified GPS or WAAS systems.

NOTE−
4. The navigation database should be current for the duration of the flight.

c. Uses of Suitable RNAV Systems. Subject to the operating requirements, operators may use a suitable RNAV system in the following ways.
  1. Determine aircraft position relative to, or distance from a VOR (“VOR” includes VOR, VOR/DME, and VORTAC facilities and “compass locator” includes locator outer marker and locator middle marker.), TACAN, NDB, compass locator, DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course.

  2. Navigate to or from a VOR, TACAN, NDB, or compass locator.

  3. Hold over a VOR, TACAN, NDB, compass locator, or DME fix.

  4. Fly an arc based upon DME.

None of the substitutions mentioned above include the localizer portion of an ILS. So you may not substitute GPS/WAAS for and ILS or localizer approach, but you may still use it for situational awareness.

Alternates with WAAS

March 1st, 2017

AIM 1−1−18. Wide Area Augmentation System (WAAS)

9. Unlike TSO−C129 avionics [GPS systems in AIM-speak], which were certified as a supplement to other means of navigation, WAAS avionics are evaluated without reliance on other navigation systems. As such, installation of WAAS avionics does not require the aircraft to have other equipment appropriate to the route to be flown. (See paragraph 1−1−17 d for more information on equipment requirements.)

(a) Pilots with WAAS receivers may flight plan to use any instrument approach procedure authorized for use with their WAAS avionics as the planned approach at a required alternate, with the following restrictions. When using WAAS at an alternate airport, flight planning must be based on flying the RNAV (GPS) LNAV or circling minima line, or minima on a GPS approach procedure, or conventional approach procedure with “or GPS” in the title. Code of Federal Regulation (CFR) Part 91 non−precision weather requirements must be used for planning. Upon arrival at an alternate, when the WAAS navigation system indicates that LNAV/ VNAV or LPV service is available, then vertical guidance may be used to complete the approach using the displayed level of service. The FAA has begun removing the Alternate Minimums NA Symbol (Alternate Minimums Not Authorized) symbol from select RNAV (GPS) and GPS approach procedures so they may be used by approach approved WAAS receivers at alternate airports. Some approach procedures will still require the Alternate Minimums NA Symbol for other reasons, such as no weather reporting, so it cannot be removed from all procedures. Since every procedure must be individually evaluated, removal of the Alternate Minimums NA Symbol from RNAV (GPS) and GPS procedures will take some time.

Note that the symbol Alternate Minimums NA Symbol means that this particular approach is not available to use as an alternate, though there may be others at the airport that are available.

Magnetic Variation

March 1st, 2017

This section of the AIM describes the reason that you may see differences between charted courses and the course on the PBN (Performance Based Navigation e.g. GPS and WAAS) system. Basically, the system uses true north to determine the course and then makes a correction to display magnetic course. It uses published airport or navaid variation, or magnetic reference bearing data, to display the magnetic course. This can result in a difference between the charted magnetic course to differ from the magnetic course displayed. The actual ground track from following the GPS course will be the same as the ground track from following the charted course.

Variations in distances may also occur since PBN system distance−to−waypoint values while DME values are slant−range distances measured to the station.

AIM Navigation Aids
1−1−17. Global Positioning System (GPS)
5. GPS Instrument Approach Procedures
(k) Impact of Magnetic Variation on PBN Systems

(1) Differences may exist between PBN systems and the charted magnetic courses on ground−based NAVAID instrument flight procedures (IFP), enroute charts, approach charts, and Standard Instrument Departure/Standard Terminal Arrival (SID/STAR) charts. These differences are due to the magnetic variance used to calculate the magnetic course. Every leg of an instrument procedure is first computed along a desired ground track with reference to true north. A magnetic variation correction is then applied to the true course in order to calculate a magnetic course for publication. The type of procedure will determine what magnetic variation value is added to the true course. A ground−based NAVAID IFP applies the facility magnetic variation of record to the true course to get the charted magnetic course.

Magnetic courses on PBN procedures are calculated two different ways. SID/STAR procedures use the airport magnetic variation of record, while IFR enroute charts use magnetic reference bearing. PBN systems make a correction to true north by adding a magnetic variation calculated with an algorithm based on aircraft position, or by adding the magnetic variation coded in their navigational database. This may result in the PBN system and the procedure designer using a different magnetic variation, which causes the magnetic course displayed by the PBN system and the magnetic course charted on the IFP plate to be different.

It is important to understand, however, that PBN systems, (with the exception of VOR/DME RNAV equipment) navigate by reference to true north and display magnetic course only for pilot reference. As such, a properly functioning PBN system, containing a current and accurate navigational database, should fly the correct ground track for any loaded instrument procedure, despite differences in displayed magnetic course that may be attributed to magnetic variation application. Should significant differences between the approach chart and the PBN system avionics’ application of the navigation database arise, the published approach chart, supplemented by NOTAMs, holds precedence.

(2) The course into a waypoint may not always be 180 degrees different from the course leaving the previous waypoint, due to the PBN system avionics’ computation of geodesic paths, distance between waypoints, and differences in magnetic variation application. Variations in distances may also occur since PBN system distance−to−waypoint values are ATDs computed to the next waypoint and the DME values published on underlying procedures are slant−range distances measured to the station. This difference increases with aircraft altitude and proximity to the NAVAID.

Missed Approach Point

February 28th, 2017

AIM – Ch5 Arrival Procedures

5−4−20. Approach and Landing Minimums
4. The missed approach point (MAP) varies depending upon the approach flown. For vertically guided approaches, the MAP is at the decision altitude/decision height. Non−vertically guided and circling procedures share the same MAP and the pilot determines this MAP by timing from the final approach fix, by a fix, a NAVAID, or a waypoint. Circling from a GLS, an ILS without a localizer line of minima or an RNAV (GPS) approach without an LNAV line of minima is prohibited.

5−4−21. Missed Approach
a. When a landing cannot be accomplished, advise ATC and, upon reaching the missed approach point defined on the approach procedure chart, the pilot must comply with the missed approach instructions for the procedure being used or with an alternate missed approach procedure specified by ATC.

5−4−21. Missed Approach
b. …when an early missed approach is executed, pilots should, unless otherwise cleared by ATC, fly the IAP as specified on the approach plate to the missed approach point at or above the MDA or DH before executing a turning maneuver.

Glossary
MISSED APPROACH POINT− A point prescribed in each instrument approach procedure at which a missed approach procedure shall be executed if the required visual reference does not exist.

AREA NAVIGATION (RNAV) APPROACH CONFIGURATION:
a. STANDARD T− An RNAV approach whose design allows direct flight to any one of three initial approach fixes (IAF) and eliminates the need for procedure turns. The standard design is to align the procedure on the extended centerline with the missed approach point (MAP) at the runway threshold, the final approach fix (FAF), and the initial approach/ intermediate fix (IAF/IF). The other two IAFs will be established perpendicular to the IF.

FAA-H-8083-16 Instrument Procedures Handbook
Minimum Descent Altitude (MDA), Decision Altitude (DA), And Decision Height (DH)

MDA—the lowest altitude, expressed in feet MSL, to which descent is authorized on final approach or during circle-to- land maneuvering in execution of a standard instrument approach procedure (SIAP) where no electronic glideslope is provided.

DA—a specified altitude in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.

DH—with respect to the operation of aircraft, means the height at which a decision must be made during an ILS, MLS, or PAR IAP to either continue the approach or to execute a missed approach.

RNAV charts show a FO waypoint as a four-pointed star enclosed in a circle. This type of waypoint is used to denote a missed approach point, a missed approach holding point, or other specific points in space that must be flown over.

I can’t find any documentation of what the MAP looks like on AeroNav charts, however several reputable sources confirm that it is the vertical bar near the upsloping dotted lines and arrow that mark the missed approach procedure.

For a LPV or LNAV/VNAV, the MAP is located at the DA on the GS. For the LP or LNAV, the MAP is typically at the runway threshold, but may be at a named fix other than the runway threshold. On the AeroNav approach charts, the MAP for the LNAV and LP is also shown in the profile view with a vertical line at the MAP. John D Collins

You can confirm this by looking at some charts with non-precision approaches. I picked KBUR because it is shown in some FAA publications as an example of missed approaches.

Missed Approach Point KBUR VOR8

Notice that in the timing section, it gives the distance from the FAF ✠ as 5.5 NM. If we look at the profile view, the distance from the ✠ to the vertical line is 5.5 NM.

This post gives some more examples. Most RNAV approaches without vertical guidance usually have MAPs located at the runway threshold. Not all non-precision MAPs (VOR, Localizer, or DME) are located at the runway threshold, though most are. In some cases the only way to find the MAP is by timing from the FAF.

VFR Lost Comms

February 27th, 2017

AIM Section 4. Two-way Radio Communications Failure

6−4−1. Two-way Radio Communications Failure

a. It is virtually impossible to provide regulations and procedures applicable to all possible situations associated with two-way radio communications failure. During two-way radio communications failure, when confronted by a situation not covered in the regulation, pilots are expected to exercise good judgment in whatever action they elect to take. Should the situation so dictate they should not be reluctant to use the emergency action contained in 14 CFR Section 91.3(b).

6−4−2. Transponder Operation During Two-way Communications Failure

a. If an aircraft with a coded radar beacon transponder experiences a loss of two-way radio capability, the pilot should adjust the transponder to reply on Mode A/3, Code 7600.

AIM 4−2−13. Communications with Tower when Aircraft Transmitter or Receiver or Both are Inoperative

a. Arriving Aircraft.

1. Receiver inoperative.
(a) If you have reason to believe your receiver is inoperative, remain outside or above the Class D surface area until the direction and flow of traffic has been determined; then, advise the tower of your type aircraft, position, altitude, intention to land, and request that you be controlled with light signals.

(b) When you are approximately 3 to 5 miles from the airport, advise the tower of your position and join the airport traffic pattern. From this point on, watch the tower for light signals. Thereafter, if a complete pattern is made, transmit your position downwind and/or turning base leg.

2. Transmitter inoperative. Remain outside or above the Class D surface area until the direction and flow of traffic has been determined; then, join the airport traffic pattern. Monitor the primary local control frequency as depicted on Sectional Charts for landing or traffic information, and look for a light signal which may be addressed to your aircraft. During hours of daylight, acknowledge tower transmissions or light signals by rocking your wings. At night, acknowledge by blinking the landing or navigation lights. To acknowledge tower transmis- sions during daylight hours, hovering helicopters will turn in the direction of the controlling facility and flash the landing light. While in flight, helicopters should show their acknowledgement of receiving a transmission by making shallow banks in opposite directions. At night, helicopters will acknowledge receipt of transmissions by flashing either the landing or the search light.

3. Transmitter and receiver inoperative.
Remain outside or above the Class D surface area until the direction and flow of traffic has been determined; then, join the airport traffic pattern and maintain visual contact with the tower to receive light signals. Acknowledge light signals as noted above.

b. Departing Aircraft.

If you experience radio failure prior to leaving the parking area, make every effort to have the equipment repaired. If you are unable to have the malfunction repaired, call the tower by telephone and request authorization to depart without two-way radio communications. If tower authorization is granted, you will be given departure information and requested to monitor the tower frequency or watch for light signals as appropriate. During daylight hours, acknowledge tower transmissions or light signals by moving the ailerons or rudder. At night, acknowledge by blinking the landing or navigation lights. If radio malfunction occurs after departing the parking area, watch the tower for light signals or monitor tower frequency.

§91.126 Operating on or in the vicinity of an airport in Class G airspace.
(d) Communications with control towers. Unless otherwise authorized or required by ATC, no person may operate an aircraft to, from, through, or on an airport having an operational control tower unless two-way radio communications are maintained between that aircraft and the control tower. Communications must be established prior to 4 nautical miles from the airport, up to and including 2,500 feet AGL. However, if the aircraft radio fails in flight, the pilot in command may operate that aircraft and land if weather conditions are at or above basic VFR weather minimums, visual contact with the tower is maintained, and a clearance to land is received. If the aircraft radio fails while in flight under IFR, the pilot must comply with §91.185.

§91.127 Operating on or in the vicinity of an airport in Class E airspace.
(c) Communications with control towers. Unless otherwise authorized or required by ATC, no person may operate an aircraft to, from, through, or on an airport having an operational control tower unless two-way radio communications are maintained between that aircraft and the control tower. Communications must be established prior to 4 nautical miles from the airport, up to and including 2,500 feet AGL. However, if the aircraft radio fails in flight, the pilot in command may operate that aircraft and land if weather conditions are at or above basic VFR weather minimums, visual contact with the tower is maintained, and a clearance to land is received. If the aircraft radio fails while in flight under IFR, the pilot must comply with §91.185.

§91.129 Operations in Class D airspace.
(d) Communications failure. Each person who operates an aircraft in a Class D airspace area must maintain two-way radio communications with the ATC facility having jurisdiction over that area.

(1) If the aircraft radio fails in flight under IFR, the pilot must comply with §91.185 [IFR operations: Two-way radio communications failure.] of the part.
(2) If the aircraft radio fails in flight under VFR, the pilot in command may operate that aircraft and land if—
  (i) Weather conditions are at or above basic VFR weather minimums;
  (ii) Visual contact with the tower is maintained; and
  (iii) A clearance to land is received.

§91.130 Operations in Class C airspace.
(a) General. Unless otherwise authorized by ATC, each aircraft operation in Class C airspace must be conducted in compliance with this section and §91.129.

§91.131 Operations in Class B airspace.
(a) Operating rules. No person may operate an aircraft within a Class B airspace area except in compliance with §91.129 and the following rules:

My Thoughts
Operating in Class B and C without a radio defaults to the operation in Class D. However, as the AIM states, It is virtually impossible to provide regulations and procedures applicable to all possible situations. If you have just entered Class B and your destination airport is not close, then the best course of action might be to turn around and exit the airspace. However, if you are transiting a Class B or Class C, then squawking 7600 and continuing on the flight path that ATC expects will cause the least concern.

If for some reason, your destination is a Class B airport, you are not on a STAR, and you are not on a flight plan, it would make the most sense to land somewhere else. Airliners are always on an IFR flight plan, so they should just follow IFR lost comms procedures.

Understanding IFR Charts

February 27th, 2017

He covers the charts in great detail and includes a couple of things that I never noticed. Like, the time zone boundaries are on the charts as well as Class G boundaries. He also explains T-routes and Q-routes if you are not familiar with them.

IFR Lost Comms

February 27th, 2017

§91.185 IFR operations: Two-way radio communications failure.
(a) General. Unless otherwise authorized by ATC, each pilot who has two-way radio communications failure when operating under IFR shall comply with the rules of this section.

(b) VFR conditions. If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the flight under VFR and land as soon as practicable.

(c) IFR conditions. If the failure occurs in IFR conditions, or if paragraph (b) of this section cannot be complied with, each pilot shall continue the flight according to the following:

  (1) Route.

  • (i) By the route assigned in the last ATC clearance received;
  • (ii) If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance;
  • (iii) In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance; or
  • (iv) In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.

  (2) Altitude. At the highest of the following altitudes or flight levels for the route segment being flown:

  • (i) The altitude or flight level assigned in the last ATC clearance received;
  • (ii) The minimum altitude (converted, if appropriate, to minimum flight level as prescribed in §91.121(c)) for IFR operations; [Minimum IFR Altitude—MEA or MORA]or
  • (iii) The altitude or flight level ATC has advised may be expected in a further clearance.

  (3) Leave clearance limit.

  • (i) When the clearance limit is a fix from which an approach begins, commence descent or descent and approach as close as possible to the expect-further-clearance time if one has been received, or if one has not been received, as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
  • (ii) If the clearance limit is not a fix from which an approach begins, leave the clearance limit at the expect-further-clearance time if one has been received, or if none has been received, upon arrival over the clearance limit, and proceed to a fix from which an approach begins and commence descent or descent and approach as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.

Route – AVEnue F
Assigned, Vectored, Expected, Filed

Altitude – MEA
Minimum IFR Altitude
Expected
Assigned
Highest for route.

The AIM has a section on lost comms as well.

Instrument Approaches

February 27th, 2017

Watching people perform approaches can help you figure out what needs to be done and when. Here are a few that I found useful.

ILS Approach

VOR Approach

Garry Wing has lots of 5-minute videos about flying, this one is longer and takes you through an approach and circle to land.

This is an entire flight from takeoff to landing with a student pilot. Lots of mistakes to learn from.

This guy has lots of flights from Auburn,. Here’s one to Oakland.

Climb Via

February 27th, 2017

CLIMB VIA– An abbreviated ATC clearance that requires compliance with the procedure lateral path, associated speed restrictions, and altitude restrictions along the cleared route or procedure. Pilot Controller Glossary

The folks at BoldMethod have a page with all of the charts and some explanation of departure procedures so you can follow along as they fly the procedure.

The FAA also has a video that promotes familiarity with “Climb Via” phraseology and RNAV SIDs (Area Navigation Standard Instrument Departures). And with the NBAA, a document describing the procedure.

Objectionable Airports

February 25th, 2017

Objectionable Airport

I ran across an airport listed on the chart as OBJECTIONABLE and wondered what it was. The FAQs at AeroNav explain it.

What does “OBJECTIONABLE” stand for on VFR Charts?

The type “OBJECTIONABLE” associated with an airport symbol indicates that an objectionable airspace determination has been made for the airport per FAA Order JO 7400.2 Section 4, Airport Charting and Publication of Airport Data. Objectionable airspace determinations can be based upon a number of factors including conflicting traffic patterns with another airport, hazardous runway conditions, or natural or man-made obstacles in close proximity to the landing area. FAA Regional Airports Offices are responsible for airspace determinations.

Question: Following the glide slope in Class E

February 23rd, 2017

When descending on an ILS you can descend to 100′ above the TDZE if you have the approach lighting system in sight. Cody Johnson wrote an article explaining how one pilot mis-interpreted what the rules allowed him to do, descended below 100′ when there were obstructions in the way and crashed into a hill.

Section 91.129(e)(3), Operations in Class D Airspace, is also extremely applicable in this accident. It says, ‘An airplane approaching to land on a runway served by a visual approach slope indicator shall maintain an altitude at or above the glide slope until a lower altitude is necessary for safe landing.’

Class C and B incorporate Section 91.129(e)(3) by reference, so the rule applies in that airspace as well. It doesn’t specifically apply to operations at airports in Class E airspace.

My question is are there any ILS approaches in Class E airspace? Is there a a rule that prohibits them, or conversely, only allows them when there is a tower?

The question was answered on Aviation.StackExchange. There is at least one, Visalia. So why don’t you have to follow the glide slope at airports in Class E?

Wonderful World of Flying on YouTube

February 23rd, 2017

Steve Kahn did a series of shows for ABC in the late 1980s called “ABCs Wide
World of Flying”. He then made a few more and sold the series as DVDs. They are now up on YouTube on his channel. I’ve linked to many of them in previous posts and found this list of what is in each one. Barry Schiff, Phil Boyer, and Rod Machado feature in them and much of the content is still relevant. I’ll provide links and highlight the good parts as time permits. Here’s the whole list to get you started.

V.1 Piper Malibu, Takeoff Techniques, Engine Controls Rigged Right?, Sentimental Journey-The B17, Switching Tanks Safely, Flying the Lancair

V.2 Mooney 252, Morning Sickness, Argus 5000, ATC at Oshkosh, Avisit to Rhinebeck, NY, Touring AOPA, Lear Jet (Part 1)

V.3 Flying the Lear Jet (Part 2), Flight Quiz, Quiet Flight Intercom, Cessna Skylane, NDB Techniques, Tsunami at Reno 1987

V.4 Crossing the Atlantic, Flight Quiz 1, Inside a FSS, Flight Quiz 2, Flashlight Please, Rejected Takeoffs & Landings, Flight Quiz 3, Propeller Handling Tips, F4U Corsair

V.5 Flying the Trinidad and Tobago, Flight Quiz 1, Making Your Home Videos Fly, Instrument Rating in 10 Days, Midair Collision Avoidance, Those Hollywood Helicopters, Flight Quiz 2, Understanding Spins

V.6 Machen Superstar, Flight Quiz 1, Flight Plan Filing by PC, Flight Quiz 2, T-6 Transition, Wheeler Express, NASA Reporting System, Flying a Taildragger

V.7 How to Fly a Seaplane, Ground Ice Precautions, Flight Quiz, Glasair III, Aero Car, Winter Preflight, Moosehead Seaplane Splash-In, Desert Vision

V.8 Slip Tips, Leaning with EGT, Tie Down Tips, The Ultimate EGT, P-51, Destination Hawaii

V.9 Flight Control Failure, Flight Quiz 1, IFR Scan Techniques, Mooney Panel Update, Flight Safety International, Flight Quiz 2, Electrical Failure, Citabria Decathlon

V.10 Beechcraft Bonanza, Glass Cockpit, Bacuum Pump Failure, A-26 Invader, World’s Best Equipped Mooney, Spruce Goose

V.11 Emergency Glide Techniques, Mooney TLS, Bose Noise-Canceling Headset, Single Pilot IFR, P-40 Warhawk

V.12 Beechcraft Staggerwing, AltAlert, Airspace Quiz, Bushmaster, Top Gun for Everyone

V.13 T-28C, Faulty Gas Caps, Measuring Airspeed, Ryan TCAD, Helicopter Transition

V.14 Questair Venture, Atlantic Crossing Part 1, Fuel System Management, Accident Tracking, Bendix/King KLN-88, Behind the Scenes at Geneseo, After-Market Turbochargers

V. 15 Pitot Static Pitfalls, Cockpit Organization, Wildcat, Wake Turbulence, TBM-700, Changing Your Oil Filter, Atlantic Crossing Part 2

V.16 Cessna 310, Performing the Loop, You Can Buy a Warbird, Landing Gear Problems, Protection Against Corrosion, Determining Practical Range

V.17 Bellanca Viking 300, Swinging Your Compass, Airplane Painting, Nose Wheel Shimmy, Propeller Failure, Color Sky Map, Airborne Radar, Sun-N-Fun EAA FLy-in

V.18 Cessna 210, Engine Failure, Fire Extinguishers, AOPA Quiz 1, Idaho Airplane Camping, AirSport Pro, Do I Buy a Single or Twin, AOPA Quiz 2

V.19 Lancair, Aircraft Ditching, Propeller Clothing, Bamboo Bomber, Aviation Weather, Garmin GPS 100, Pilot Profile

V.20 The A.G. Tiger, Weight and Balance, NorthStar M2V GPS, Spartan Executive, Maneuvering Speed, Flying to Mexico, Engine Overhauls, Schiff and Son

V.21 Mooney MSE, Approach Lighting Systems, How Things Work, Supplemental Oxygen, Antiques, Fliers’ Fantasy Vacation, Cloud Chasers

V.22 Chipmunk, ASR-9 Radar, Cayman Caravan, Engine Instruments, IFR Departures, Gyroplane, Aerostar Convention

V.23 Commander 114B, Stabilized Approach, SR-71, Nova Scotia, GPS Approaches.

RNAV Arrival

February 23rd, 2017

Pilot Controller Glossary
AREA NAVIGATION (RNAV) APPROACH CONFIGURATION:

a. STANDARD T− An RNAV approach whose design allows direct flight to any one of three initial approach fixes (IAF) and eliminates the need for procedure turns. The standard design is to align the procedure on the extended centerline with the missed approach point (MAP) at the runway threshold, the final approach fix (FAF), and the initial approach/ intermediate fix (IAF/IF). The other two IAFs will be established perpendicular to the IF.

b. MODIFIED T− An RNAV approach design for single or multiple runways where terrain or operational constraints do not allow for the standard T. The “T” may be modified by increasing or decreasing the angle from the corner IAF(s) to the IF or by eliminating one or both corner IAFs.

c. STANDARD I− An RNAV approach design for a single runway with both corner IAFs eliminated. Course reversal or radar vectoring may be required at busy terminals with multiple runways.

d. TERMINAL ARRIVAL AREA (TAA)− The TAA is controlled airspace established in conjunction with the Standard or Modified T and I RNAV approach configurations. In the standard TAA, there are three areas: straight-in, left base, and right base. The arc boundaries of the three areas of the TAA are published portions of the approach and allow aircraft to transition from the en route structure direct to the nearest IAF. TAAs will also eliminate or reduce feeder routes, departure extensions, and procedure turns or course reversal.

1. STRAIGHT-IN AREA− A 30NM arc centered on the IF bounded by a straight line extending through the IF perpendicular to the intermediate course.

2. LEFT BASE AREA− A 30NM arc centered on the right corner IAF. The area shares a boundary with the straight-in area except that it extends out for 30NM from the IAF and is bounded on the other side by a line extending from the IF through the FAF to the arc.

3. RIGHT BASE AREA−A 30NM arc centered on the left corner IAF. The area shares a boundary with the straight-in area except that it extends out for 30NM from the IAF and is bounded on the other side by a line extending from the IF through the FAF to the arc.

TAA Area

AIM 5−4−5. Instrument Approach Procedure (IAP) Charts
d. Terminal Arrival Area (TAA)

1. The TAA provides a transition from the en route structure to the terminal environment with little required pilot/air traffic control interface for aircraft equipped with Area Navigation (RNAV) systems. A TAA provides minimum altitudes with standard obstacle clearance when operating within the TAA boundaries. TAAs are primarily used on RNAV approaches but may be used on an ILS approach when RNAV is the sole means for navigation to the IF; however, they are not normally used in areas of heavy concentration of air traffic.

5 (b) Once cleared for the approach, pilots may descend in the TAA sector to the minimum altitude depicted within the defined area/subdivision, unless instructed otherwise by air traffic control.

6. U.S. Government charts depict TAAs using icons located in the plan view outside the depiction of the actual approach procedure. (See FIG 5−4−5). Use of icons is necessary to avoid obscuring any portion of the “T” procedure (altitudes, courses, minimum altitudes, etc.). The icon for each TAA area will be located and oriented on the plan view with respect to the direction of arrival to the approach procedure, and will show all TAA minimum altitudes and sector/radius subdivisions. The IAF for each area of the TAA is included on the icon where it appears on the approach to help the pilot orient the icon to the approach procedure. The IAF name and the distance of the TAA area boundary from the IAF are included on the outside arc of the TAA area icon.

TAA Example

Note: Not all RNAV approaches have a TAA. If there is an MSA circle on the chart, there is no TAA.

BruceAir gives some examples of how ATC might clear you into a TAA and what altitude they expect you to fly.

Missed Approach Waypoint – WAAS

February 23rd, 2017

AIM 1−1−18. Wide Area Augmentation System (WAAS)
d. Flying Procedures with WAAS

7. The Along−Track Distance (ATD) during the final approach segment of an LNAV procedure (with a minimum descent altitude) will be to the MAWP. On LNAV/VNAV and LPV approaches to a decision altitude, there is no missed approach waypoint so the along−track distance is displayed to a point normally located at the runway threshold. In most cases, the MAWP for the LNAV approach is located on the runway threshold at the centerline, so these distances will be the same. This distance will always vary slightly from any ILS DME that may be present, since the ILS DME is located further down the runway. Initiation of the missed approach on the LNAV/ VNAV and LPV approaches is still based on reaching the decision altitude without any of the items listed in 14 CFR Section 91.175 being visible, and must not be delayed while waiting for the ATD to reach zero. The WAAS receiver, unlike a GPS receiver, will automatically sequence past the MAWP if the missed approach procedure has been designed for RNAV. The pilot may also select missed approach prior to the MAWP; however, navigation will continue to the MAWP prior to waypoint sequencing taking place.

Pilot Math – Descent Rate

February 19th, 2017

Suppose you are flying into an airport with a VASI. When the VASI is in sight and you are descending on it, what should be your rate of descent?

AIM 2−1−2. Visual Glideslope Indicators
2. Two−bar VASI installations provide one visual glide path which is normally set at 3 degrees. Three−bar VASI installations provide two visual glide paths. The lower glide path is provided by the near and middle bars and is normally set at 3 degrees while the upper glide path, provided by the middle and far bars, is normally 1/4 degree higher. This higher glide path is intended for use only by high cockpit aircraft to provide a sufficient threshold crossing height.

One way to find out would be to go out and fly it and see what rate of descent you need for various speeds. It’s complicated somewhat because your rate of descent depends on your groundspeed—not airspeed.

The FAA includes a table on the back cover of each Terminal Procedures Publication that tells you the rate of descent or climb for various ground speeds and angles.

The part we are interested in is shown below:

Climb Descent Rates

If you are on a 3° VASI then you should be descending a little less than 500 fpm in most small GA aircraft. If you are in a faster plane, then a little faster.

A general rule of thumb is that for a 3 degree glideslope the descent rate is 300′ per one nautical mile (according to the table it is actually 318 fpnm). A VASI is normally visible and the descent path is protected at 4 miles so you should be at about 1200 feet above the airport when the VASI becomes visible. Steeper than 3 degrees would be a little more.

Another convenient formula is to multiply your groundspeed (or airspeed if you have nothing else) by 5 to determine the approximate rate of descent to make good a 3 degree glideslope. (You can verify this by looking at the table.)

A typical approach speed for a light airplane is 90 knots which gives about 450 fpm which is a little lower than the 478 fpm you get from the table. In any event, close enough to get you there.

Now what about on the ILS?

AIM 1−1−9. Instrument Landing System (ILS)
d. Glide Slope/Glide Path
3. The glide path projection angle is normally adjusted to 3 degrees above horizontal so that it intersects the MM at about 200 feet and the OM at about 1,400 feet above the runway elevation.

It’s usually the same. Remember that it is groundspeed—not airspeed. So if you normally fly the approach at 100 kts, your groundspeed will probably be less than that—significantly so if there is a large headwind.

In a no-wind condition, we need to interpolate to get 100kts.

(637-478) * ⅓ + 478 = 531 kts.

El Niño

February 16th, 2017

Walker Circulation

I don’t think that any of the FAA books cover El Niños, but as flyers, we should be aware of their impact. The drought in California from 2012-2016 was primarily caused by the weather pattern associated with the lack of an El Niño, a La Niña, as well as the effects of global climate change. In 2017, the west coast has been hit with many atmospheric rivers caused by lingering effects of an El Niño.

The NASA Earth Observatory has a long article explaining how they form and the worldwide effects on weather.

Required Equipment

February 10th, 2017

14 CFR §91.205 Instrument and equipment requirements is fairly wordy, so to remember the equipment needed for day VFR pilots use A TOMATO FLAMES. For night flight and IFR you don’t really need any acronyms (though some people like GRABCARD for Instrument flight) since the additional items are fairly obvious.

Day VFR
Anti-collision lamps (certificated after March 11, 1996)

Tachometer
Oil pressure gauge
Manifold pressure gauge for each altitude engine
Airspeed indicator
Temperature gauge for each liquid cooled engine
Oil temperature gauge for each air cooled engine

Fuel level gauge
Landing gear position indicator
Altimeter
Magnetic direction indicator (Compass)
Emergency locator transmitter (ELT)
Seat belts (and airplanes manufactured after July 18, 1978 Safety Harness)

Day VFR
Some people like to remember the day items by grouping them into categories:
Engine
Fuel level gauge
Oil temperature gauge for each air cooled engine
Oil pressure gauge
Tachometer

Manifold pressure gauge for each altitude engine
Temperature gauge for each liquid cooled engine

Instruments
Airspeed indicator
Altimeter
Magnetic direction indicator (Compass)

Safety
Seat belts
Emergency locator transmitter (ELT)
Anti-collision lamps (certificated after March 11, 1996)
Landing gear position indicator
Safety Harness ( manufactured after July 18, 1978 )

Night
Everything from Day plus:
Adequate source of electrical energy
Fuses
Position indicator lamps

IFR
Everything from Day plus:
Generator or alternator of adequate capacity.
Two-way radio communication and navigation equipment suitable for the route to be flown.
Clock

(Normal six pack except VSI)
Sensitive altimeter adjustable for barometric pressure.
Gyroscopic rate-of-turn indicator
Slip-skid indicator
Gyroscopic pitch and bank indicator (artificial horizon).
Gyroscopic direction indicator (directional gyro or equivalent).

IFR Mnemonic— GRABCARD
Generator or Alternator
Radios for Communication and Navigation
Altimeter – Sensitive
Ball – Slip/Skid Indicator
Clock
Attitude Indicator
Rate of Turn Indicator
Directional Gyro (Heading Indicator)

For Hire
Landing light at night
Flotation Device if outside gliding distance

§91.213 Inoperative instruments and equipment.
a) Except as provided in paragraph (d) of this section, no person may take off an aircraft with inoperative instruments or equipment installed unless the following conditions are met:

Minimum Equipment List exists for that aircraft—not likely for your aircraft.

The inoperative instruments and equipment are not— (i) Part of the VFR-day type certification instruments and equipment…

The inoperative instruments and equipment… Removed from the aircraft, the cockpit control placarded, and the maintenance recorded in accordance with §43.9 of this chapter; or
Deactivated and placarded “Inoperative.

You can fly with equipment that is inoperative provided that it is marked as INOP on the panel and an appropriate logbook entry has been made if maintenance has been performed.

Obviously, you cannot fly at night, IFR, or for hire if the equipment is on the list of required items. It is possible to fly with inoperative items, on the VFR list, if a ferry permit is obtained.

If you read the requirements carefully, you can see that they require an altimeter for day flight and at night they require a sensitive altimeter. I stumbled across this tidbit about J3 Cubs at the Air and Space Museum. Notice the lack of a Kollsman window. That why it isn’t a sensitive altimeter and an aircraft with this altimeter cannot fly IFR.

Altimeter J3 Cub

This altimeter was one of the standard instruments onboard the Piper Cub J-3 and L-4 aircraft. Designed by C.G. Taylor in 1931 to be economical and easy to fly, the Cub had only four instruments: an altimeter, a tachometer, an oil temperature gauge and pressure gauge.

Even if you have all the equipment for your flight you still may not be able to take off.
§91.213 Inoperative instruments and equipment.
(d) Except for operations conducted in accordance with paragraph (a) or (c) of this section, a person may takeoff an aircraft in operations conducted under this part with inoperative instruments and equipment without an approved Minimum Equipment List provided—

(3) The inoperative instruments and equipment are—
  (i) Removed from the aircraft, the cockpit control placarded, and the maintenance recorded in accordance with §43.9 of this chapter; or
  (ii) Deactivated and placarded “Inoperative.” If deactivation of the inoperative instrument or equipment involves maintenance, it must be accomplished and recorded in accordance with part 43 of this chapter; and…

Hazardous Attitudes

February 9th, 2017

The FAA has been emphasizing recognition and the antidote to hazardous attitudes and asks about them on most of the knowledge tests. The Pilots Handbook of Aeronautical Knowledge (FAA-H-8083-25B) lists them.

Being fit to fly depends on more than just a pilot’s physical condition and recent experience. For example, attitude affects the quality of decisions. Attitude is a motivational predisposition to respond to people, situations, or events in a given manner. Studies have identified five hazardous attitudes that can interfere with the ability to make sound decisions and exercise authority properly: anti-authority, impulsivity, invulnerability, macho, and resignation.

Anti-authority: “Don’t tell me.”
This attitude is found in people who do not like anyone telling them what to do. In a sense, they are saying, “No one can tell me what to do.” They may be resentful of having someone tell them what to do or may regard rules, regulations, and procedures as silly or unnecessary. However, it is always your prerogative to question authority if you feel it is in error.

Impulsivity: “Do it quickly.”
This is the attitude of people who frequently feel the need to do something, anything, immediately. They do not stop to think about what they are about to do, they do not select the best alternative, and they do the first thing that comes to mind.
Invulnerability: “It won’t happen to me.”

Many people falsely believe that accidents happen to others, but never to them. They know accidents can happen, and they know that anyone can be affected. However, they never really feel or believe that they will be personally involved. Pilots who think this way are more likely to take chances and increase risk.

Macho: “I can do it.”
Pilots who are always trying to prove that they are better than anyone else think, “I can do it—I’ll show them.” Pilots with this type of attitude will try to prove themselves by taking risks in order to impress others. While this pattern is thought to be a male characteristic, women are equally susceptible.

Resignation: “What’s the use?”
Pilots who think, “What’s the use?” do not see themselves as being able to make a great deal of difference in what happens to them. When things go well, the pilot is apt to think that it is good luck. When things go badly, the pilot may feel that someone is out to get them or attribute it to bad luck. The pilot will leave the action to others, for better or worse. Sometimes, such pilots will even go along with unreasonable requests just to be a “nice guy.”

Antidotes
Follow the rules. They are usually right.
Not so fast. Think first.
It could happen to me.
Taking chances is foolish.

None of this is new. The Air Force recognized this years ago and put out this movie.
F-86D Sabre Jet “No Sweat” circa 1955 United States Air Force Pilot Training Film

The FAA put out a movie that highlights some of these as well, especially the Don’t tell me. attitude.
Density Altitude with Harry Bliss

Approach Plate Videos

February 9th, 2017

Will Liebhaber has a bunch of good videos for pilots. These are the ones that explain how to use the NACO AeroNav charts put out by the FAA—the charts that come with most EFBs like ForeFlight, WingsX, and Garmin Pilot. For the most part, the videos just explain stuff that you can get from reading the legend on the TPP, but if you are just starting out in your instrument training, these videos give you a basic understanding of approach charts in around 45 minutes. Even if you have been flying IFR for a while, you’ll probably pick up somethings that you didn’t know.

Approach Plate Basics

Approach Plate Margin Data

Approach Plate Pilot Briefing

Approach Plate Plan View

Approach Plate Profile View
Two observations on this video. For Part 91 operations, the pilot can start the approach no matter what ceiling and visibility is reported by the tower. That’s not the case for Part 135 and 121. Flight visibility, not reported visibility, determines whether the pilot can continue the approach. However, if the flight visibility is less than the minimum, then it is highly unlikely that the pilot will be able to see any of the 10 items required for landing.

His observation about the numbers in parentheses, while probably correct, is not what the legend says those numbers mean. According to the legend, they are for military use and can be ignored by civilian pilots.

Approach Plate Minima (Minimums) Section

Approach Plate Airport Diagram

Jeppesen vs. FAA (NACO) Instrument Charts

Approach Plate Overview with Fly8MA

IFR Pilot Refresher Clinic

February 9th, 2017

Wednesday, February 24, 2010
I found this slide show on the FAA website and thought it was worth expanding.

Topics For Discussion
– Expected Performance And Equipment Required
– Alternates
– Airport Environment
– Fuel and Delays
– SIDs and STARs
– Enroute Procedures
– Approach Procedures
– Equipment Problems

Sources
– Pilot’s Handbook of Aeronautical Knowledge – Airplane Flying Handbook
– Instrument Procedures Handbook
– Instrument Flying Handbook
– Practical Test Standards
– Federal Aviation Regulations

Expected Performance & Equipment Required

Expected Performance: Pilot
– Must have a current BFR Flight Review
– Must be Instrument Current or have a Current IPC (Instrument Proficiency Check)
– Instrument Experience Requirements

§61.57 Recent flight experience: Pilot in command.
(i) Six instrument approaches.
(ii) Holding procedures and tasks.
(iii) Intercepting and tracking courses through the use of navigational electronic systems.

• After the First 6 months
  FAA allows a 6 month grace period to become instrument current
  No longer allowed to use the Instrument Flight Rules
  Must use an appropriately rated safety pilot

14 CFR §91.109 Flight instruction; Simulated instrument flight and certain flight tests.
(1) The other control seat is occupied by a safety pilot who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft being flown.

• Must make a logbook entry
14 CFR § 61.51 Pilot logbooks.
(3) For the purposes of logging instrument time to meet the recent instrument experience requirements of §61.57(c) of this part, the following information must be recorded in the person’s logbook—
  (i) The location and type of each instrument approach accomplished; and
  (ii) The name of the safety pilot, if required.

• After 12 months
Must conduct either an IPC with a CFII, a DPE, or take a new Instrument Checkride
(d) Instrument proficiency check. Except as provided in paragraph (e) of this section, a person who has failed to meet the instrument experience requirements of paragraph (c) for more than six calendar months may reestablish instrument currency only by completing an instrument proficiency check.

Expected Performance: Aircraft & Pilot
• Pilots should familiarize themselves with all the facilities and services available along the planned route of flight.
• Facilities: Runway length, Airport Elevation, Approaches, etc.
• Always know where the nearest VFR conditions can be found, and be prepared to head in that direction if the situation deteriorates or equipment malfunctions

Expected Performance: Aircraft

• ATC is expecting the aircraft to climb or descend at a minimum of 500 feet/minute
  If unable, advise ATC as soon as possible

• When the aircraft is within 1000 feet of altitude, ATC is expected the aircraft to climb from 500 to 1500 feet / minute

• If cleared for a DP or STAR, follow the charted altitudes and airspeeds

Required Equipment

• Must have VFR Day & Night Equipment in addition to:
• Required Aircraft IFR Equipment

– Generator (Alternator)
– Radios
– Altimeter (Pressure Sensitive)
– Ball (Inclinometer)
– Clock (Second Hand Sweep)
– Attitude Indicator
– Rate of Turn Indicator
– Directional Gyro
– Do not need a VSI

• Required Inspections
– Annual Inspection
– 100-Hour Inspection (If for hire)
– Transponder (Every 24 Calendar Months)
– Altimeter (Every 24 Calendar Months)
– Pitot Static System (Every 24 Calendar Months)
– ELT (Every 24 Calendar Months)
– VOR (Every 30 Days)

– Acronym A1TAPEV

• VOR Checks
– Airborne Checkpoint (+/- 6°)
– Ground Checkpoint (+/- 4°)
– VOT (+/- 4°)
– Dual VORs (+/- 4° difference)

Alternates

§91.167 (b) (2) (i) For aircraft other than helicopters. For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles.

1–2–3 Rule
• 1 hour before or after your ETA
• 2000 foot ceiling or below
• 3 miles visibility or below

Do I need an alternate? (FAR 91)
• No symbol – airport is good to go with standard alternate minimums.
Alternate Symbol airport has nonstandard IFR alternate minimums Civil pilots should refer to the Alternate Minimums Section
Alternate NA Symbol signifies that this approach is Not Authorized for use as an alternate due to unmonitored facility or the absence of weather reporting service.

• Depending on type of approach into the airport and the weather reported at the ETA
– Precision Approach – 600 foot ceiling and 2 miles visibility
– Non Precision Approach – 800 foot ceiling and 2 miles visibility
– No Published Approach – 1000 foot ceiling and 3 miles visibility

§91.169 IFR flight plan: Information required.
(c) IFR alternate airport weather minima. Unless otherwise authorized by the Administrator, no person may include an alternate airport in an IFR flight plan unless appropriate weather reports or weather forecasts, or a combination of them, indicate that, at the estimated time of arrival at the alternate airport, the ceiling and visibility at that airport will be at or above the following weather minima:

(1) If an instrument approach procedure has been published in part 97 of this chapter, or a special instrument approach procedure has been issued by the Administrator to the operator, for that airport, the following minima:
  (i) For aircraft other than helicopters: The alternate airport minima specified in that procedure, or if none are specified the following standard approach minima:
    (A) For a precision approach procedure. Ceiling 600 feet and visibility 2 statute miles.
    (B) For a nonprecision approach procedure. Ceiling 800 feet and visibility 2 statute miles.

(2) If no instrument approach procedure has been published in part 97 of this chapter and no special instrument approach procedure has been issued by the Administrator to the operator, for the alternate airport, the ceiling and visibility minima are those allowing descent from the MEA, approach, and landing under basic VFR.

§91.155 Basic VFR weather minimums.
(c) Except as provided in §91.157, no person may operate an aircraft beneath the ceiling under VFR within the lateral boundaries of controlled airspace designated to the surface for an airport when the ceiling is less than 1,000 feet.

(d) Except as provided in §91.157 of this part, no person may take off or land an aircraft, or enter the traffic pattern of an airport, under VFR, within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport—
  (1) Unless ground visibility at that airport is at least 3 statute miles; or
  (2) If ground visibility is not reported at that airport, unless flight visibility during landing or takeoff, or while operating in the traffic pattern is at least 3 statute miles.

• How low can I go at the alternate?
– Precision Approach – 200 foot ceiling and 1/2 mile visibility
– Non Precision Approach – 400 foot ceiling and 1 mile visibility
– The minimums published on the approach

Airport Environment

• Takeoff Minimums
– In the event of an emergency, a decision must be made to either return to the departure airport or fly directly to a takeoff alternate.
– The FAA establishes takeoff minimums for every airport that has published Standard Instrument Approaches. Legally, under 14 CFR 91 a zero/zero departure may be made, but it is never advisable.

§91.175 Takeoff and landing under IFR.
(f) Civil airport takeoff minimums. This paragraph applies to persons operating an aircraft under part 121, 125, 129, or 135 of this chapter.
  (1) Unless otherwise authorized by the FAA, no pilot may takeoff from a civil airport under IFR unless the weather conditions at time of takeoff are at or above the weather minimums for IFR takeoff prescribed for that airport under part 97 of this chapter.
  (2) If takeoff weather minimums are not prescribed under part 97 of this chapter for a particular airport, the following weather minimums apply to takeoffs under IFR:
    (i) For aircraft, other than helicopters, having two engines or less—1 statute mile visibility.
    (ii) For aircraft having more than two engines— 1⁄2 statute mile visibility.
    (iii) For helicopters— 1⁄2 statute mile visibility.

• AeroNav charts list takeoff minimums only for the runways at airports that have other than standard minimums. These takeoff minimums are listed by airport in alphabetical order in the front of the TPP booklet.

• If an airport has non-standard takeoff minimums, a Alternate Symbol will be placed in the notes sections of the instrument procedure chart.

Airport Diagrams
• For select airports, AeroNav prints an airport diagram.
If you don’t have access to them in your EFB, you can download them from the FAA

– It is a full page depiction of the airport that includes the same features of the airport sketch plus additional details such as taxiway identifiers, airport latitude and longitude, and building identification.

– The airport diagrams are also available in the Airport / Facility Directory Chart Supplement
– The sketch is depicted in the lower left or right of an IAP.
– It depicts the runways, their length, width, and slope, the touchdown zone elevation, the lighting system installed on the end of the runway, and taxiways.

Fuel & Delays

• Aircraft must have enough fuel to reach your destination, fly to your alternate, with an additional 45 minutes at cruise power

ASRS Callback

A “fuel emergency” declaration is not defined in the Aeronautical Information Manual (AIM) or Federal Aviation Regulations, but is widely understood in the industry to mean a condition in which in the judgment of the pilot-in-command, it is necessary to proceed directly to the airport of intended landing due to low fuel. Use of this term conveys an explicit understanding that priority handling by ATC is both required and expected.

In contrast, the AIM (section 5-5-15) and Pilot/Controller Glossary provide the following definition of a “minimum fuel” declaration: “Indicates an aircraft’s fuel supply has reached a state where, upon reaching the destination, it can accept little or no delay. This is not an emergency situation but merely indicates an emergency situation is possible should any undue delay occur.”

The ATC Handbook (ATP 7110.65P: 2-1-8) adds the following guidance for controllers:
“A minimum fuel advisory does not imply a need for traffic priority. Common sense and good judgment will determine the extent of assistance to be given in minimum fuel situations.”

• Fuel Emergencies
– Declaring minimum fuel means you cannot accept undue delay in your flight
– Declaring an emergency and landing safely will not result in talking to the FAA
– However declaring and emergency and NOT landing safely, or refusing to declare and emergency and NOT landing safety will result in talking to the FAA

SIDs and STARs

• Departure procedures are preplanned routes that provide transitions from the departure airport to the en route structure.
– They also allow for efficient routing of traffic and reductions in pilot/controller workloads.
– Departure design criterion assumes an initial climb of 200 feet per nautical mile after crossing the departure end of the runway (DER) at a height of at least 35 feet and no turns before 400′ AGL

• There are two types of DPs: Obstacle Departure Procedures (ODPs) and Standard Instrument Departures (SIDs)

• Obstacle Departure Procedures (ODPs) are only used for obstruction clearance and do not include ATC related climb requirements. An ODP must be developed when obstructions penetrate the 40:1 departure plain.

• SIDS are designed at the request of ATC in order to increase capacity of terminal airspace. The primary goal is to reduce ATC/pilot workload while providing seamless transitions to the en route structure

• DPs are also categorized by equipment requirements as follows:
– Non-RNAV DP. Established for aircraft equipped with conventional avionics using ground-based NAVAIDs
– RNAV DP. Established for aircraft equipped with RNAV avionics; e.g., GPS, VOR/DME, etc. Automated vertical navigation is not required. Prior to using GPS, RAIM availability should be checked with the receiver or a Flight Service Station
Standard Instrument Departures
– Radar DP. Radar SIDs are established when ATC has a need to vector aircraft on departure to a particular route, NAVAID, or Fix. Radar vectors may also be used to join conventional or RNAV navigation SIDs

Departure Procedure Responsibility
• Responsibility for the safe execution of departure procedures rests on the shoulders of both ATC and the pilot.
• ATC is responsible for specifying the direction of takeoff or initial heading when necessary, and including departure procedures as part of the ATC clearance when pilot compliance for separation is necessary.
• The pilot must acknowledge receipt and understanding of an ATC clearance, request clarification of clearances, request an amendment to a clearance if it is unacceptable from a safety perspective or cannot be complied with.

Departures from Tower-Controlled Airports
– Normally you request your IFR clearance through ground control or clearance delivery
– Once you have received your clearance, it is your responsibility to comply with the instructions as given and notify ATC if you are unable to comply with the clearance
– Communication frequencies for the various controllers are listed on departure, approach, and airport charts as well as the A/FD.

Departures from Airports Without an Operating Control Tower
– You should file your flight plan at least 30 minutes in advance
– During your planning phase, investigate the departure airport’s method for receiving an instrument clearance.
– You can contact the Flight Service Station on the ground by telephone and they will request your clearance from ATC
– You must depart the airport before the clearance void time; if you fail to depart, you must contact ATC by a specified notification time

AIM 5−2−8. Instrument Departure Procedures (DP) − Obstacle Departure Procedures (ODP) and Standard Instrument Departures (SID)

1. Unless specified otherwise, required obstacle clearance for all departures, including diverse, is based on the pilot crossing the departure end of the runway at least 35 feet above the departure end of run- way elevation, climbing to 400 feet above the departure end of runway elevation before making the initial turn, and maintaining a minimum climb gradient of 200 feet per nautical mile (FPNM), unless required to level off by a crossing restriction, until the minimum IFR altitude.

ODPs are recommended for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC.

Ground Communications Outlets
– This has been developed in conjunction with the capability to contact ATC and AFSS via VHF radio to a telephone connection to obtain an instrument clearance or close a VFR/IFR flight plan
– You can use four key clicks on your VHF radio to contact the nearest ATC facility and six key clicks to contact the local AFSS, but it is intended to be used only as a ground operational tool
– The GCO should help relieve the need to use the telephone to call ATC and the need to depart into marginal conditions just to achieve radio contact
– GCO information is listed on airport charts and instrument approach charts with other communications frequencies

Standard Terminal Arrival Routes
• The STAR provides a common method for leaving the en route structure and navigating to your destination
• Big differences between DPs and Stars
• DPs start at the pavement and connect to the en route structure. STARs on the other hand, start at the en route structure and they end at a fix or NAVAID
• Primarily STARs serve multiple airports
• STAR procedures typically include a standardized descent gradient at and above 10,000 feet MSL of 318 feet per NM, or 3 degrees
• If a speed reduction is needed a general guideline is typically to add 1 NM for each ten knots

– STARs usually are named according to the point at which the procedure begins
– The STAR name is usually the same as the last fix on the en route transitions
– A STAR that commences at the CHINS Intersection becomes the CHINS ONE ARRIVAL.
– When a significant portion of the arrival is revised, such as an altitude, a route, or data concerning the NAVAID, the number of the arrival changes. For example, the CHINS ONE ARRIVAL is now the CHINS FOUR ARRIVAL
– In addition, some STARs require that you use DME and/or ATC RADAR

AIM 5−4−1. Standard Terminal Arrival (STAR) Procedures

c. Use of STARs requires pilot possession of at least the approved chart. RNAV STARs must be retrievable by the procedure name from the aircraft database and conform to charted procedure. As with any ATC clearance or portion thereof, it is the responsibility of each pilot to accept or refuse an issued STAR.

Holding Procedures
• Each holding pattern has a fix, a direction to hold, a course or radial, and the direction on which the aircraft is to hold
• Speed of the aircraft affects the size of a holding pattern therefore speed limits have been set depending on the altitude and ATC need
• Time plays another factor into a holding pattern. under 14,000 feet MSL, and 1 minute 30 seconds over 14,001 feet MSL.
• Time can be replaced by distance if the aircraft has DME or an IFR-certified GPS

Holding Procedures
• There are 3 entries an aircraft can use to enter a hold. Originally the FAA mandated the entry, today you can enter every hold from a direct entry if you desire
Holding Entry


Altitude (MSL)    Airspeed (KIAS)    Leg Time
MHA - 6,000'           200           1 minute
6,001' - 14,000’       230           1 minute 30 Seconds
14,001' and above      265           1 minute 30 Seconds

AIM 5-3-8. Holding

i. An ATC clearance requiring an aircraft to hold at a fix where the pattern is not charted will include the following information: (See FIG 5-3-2.)
1. Direction of holding from the fix in terms of the eight cardinal compass points (i.e., N, NE, E, SE, etc.).
2. Holding fix (the fix may be omitted if included at the beginning of the transmission as the clearance limit).
3. Radial, course, bearing, airway or route on which the aircraft is to hold.
4. Leg length in miles if DME or RNAV is to be used (leg length will be specified in minutes on pilot request or if the controller considers it necessary).
5. Direction of turn if left turns are to be made, the pilot requests, or the controller considers it necessary.
6. Time to expect further clearance and any pertinent additional delay information.

Enroute Procedures

• Course To Be Flown
– Part 91.181 is the basis for the course to be flown
– Pilots must either fly along the centerline on an airway or, along the direct course between navigational aids
– The regulation also allows an aircraft to pass clear of other traffic in VFR conditions

§91.181 Course to be flown.

Unless otherwise authorized by ATC, no person may operate an aircraft within controlled airspace under IFR except as follows:
(a) On an ATS route, along the centerline of that airway.
(b) On any other route, along the direct course between the navigational aids or fixes defining that route. However, this section does not prohibit maneuvering the aircraft to pass well clear of other air traffic or the maneuvering of the aircraft in VFR conditions to clear the intended flight path both before and during climb or descent.

Airway Structure
1.) Lower Stratum – an airway structure that extends from the base of controlled airspace to FL180.
2.) Second Stratum – contains identifiable Jet Routes from FL180 to FL450
3.) Third Stratum – Random point-to-point navigation above FL450

Air Route Traffic Control Centers

– ARTCCs provide the central authority for issuing IFR clearances and nationwide monitoring of each IFR flight
– There are 20 ARTCCs in the United States, and each containing between 20 to 80 sectors
– Appropriate radar and communication sites are connected to the Centers by microwave links and telephone lines
– When climbing after takeoff, an IFR flight is either in contact with a radar equipped local departure control or, in some areas, an ARTCC facility
– As a flight transitions to the en route phase, pilots typically expect a handoff from departure control to a Center frequency if not already in contact with the Center
– Accepting radar vectors from controllers does not relieve pilots of their responsibility for keeping track of altitude and position when during each phases of flight changes, and to aid in the management of air traffic

Preferred IFR Routes
– Preferred IFR routes are designed to provide a flow of air traffic in the major terminal and en route flight environments
– These routes are published in the Airport/Facility Directory Chart Supplement for the low and high altitude stratum
– These help pilots to plan a route to minimize route mileage
– Routes beginning or ending with a fix indicate that pilots will be routed to these fixes via a SID, vectors, or a STAR
– Routes where several airports are in proximity they are listed under the principal airport and categorized as a metropolitan area; e.g., New York Metro Area.
– If more than one route is listed both routes have equal priority for use.

Monitoring of Navigation Facilities
– VOR, VORTAC, VOR/DME, ILS facilities, NDBs, and Marker Beacons are provided with an internal monitoring feature
– Internal monitoring is provided at the facility through the use of equipment that causes a facility shutdown if performance deteriorates below established tolerances
– Older NDBs (both Federal and Non-Federal) do not have the internal feature and therefore are checked at least once each hour

– ARTCCs are usually the control point for NAVAID facility status.
– Pilots can also query the appropriate FAA facility if they have questions in flight regarding NAVAID status, or by checking the NOTAMs prior to flight since NAVAIDs and associated monitoring equipment are continuously changing

NAVAID Service Volume
-Each class of NAVAID (VOR, VOR/DME, or VORTAC) has an established operational service volume to ensure adequate signal coverage and frequency protection
-When using VORs for direct route navigation, the following guidelines apply:

• For operations that are off airways below 18,000 feet MSL, pilots should use aids not more than 80 NM apart

– If using GPS for the route, the pilot can fly outside the service volume of some NAVAIDs, during this operation, the pilot has a responsibility for staying on the authorized direct route
– ATC uses radar flight following for the purpose of aircraft separation. If ATC initiates a direct route that exceeds NAVAID service volume limits, ATC also provides radar navigational assistance as necessary

Changeover Points
– When flying airways, pilots normally change frequencies midway between navigation aids
– If the navigation signals cannot be received at the midpoint a COP is depicted and shows the distance in NM to each NAVAID
– COPs indicate the point where a frequency change is necessary to receive course guidance

– These change over points divide an airway or route segment and ensure continuous reception of navigation signals at the prescribed minimum en route IFR altitude
– Where radio frequency interference or other navigation signal problems exist, the COP is placed at the optimum location

IFR Enroute Altitudes
– For IFR operations, regulations require that pilots operate their aircraft at or above minimum altitudes
– Minimum altitude rules are designed to ensure safe vertical separation between the aircraft and the terrain

• Minimum Enroute Altitude
– This is the lowest published altitude that assures acceptable navigational signal coverage and meets obstacle clearance requirements
– MEAs are established based upon obstacle clearance over terrain and manmade objects, although adequate communication at the MEA is not guaranteed

• Minimum Obstruction Clearance Altitude
– This is the lowest published altitude in effect between VOR airways.
– This altitude assures acceptable navigational signal coverage only within 22 NM of a VOR

• Minimum Vectoring Altitude
– These are established for use by ATC when being vectored. The MVA provides 1,000 feet of clearance above the highest obstacle and 2,000 feet in designated mountainous areas

– Some MVAs may be lower than MEAs, or MOCAs depicted on charts for a given location

• Maximum Authorized Altitude
– This is a published altitude representing the maximum usable altitude for a route segment
– MAAs represent procedural limits determined by limitations of ground based facilities.

• Minimum Reception Altitude
– This is the minimum altitude that a navigation signal can be received for the route and for off- course NAVAID facilities that determine a fix

• Minimum Crossing Altitude
– This is the lowest altitude at certain fixes at which the aircraft must cross when proceeding in the direction of a higher minimum en route IFR altitude
– MCAs are established where obstacles intervene to prevent pilots from maintaining obstacle clearance

– The standard for determining the MCA is based upon the following climb gradients
  Sea level through 5,000 feet MSL — 150 feet per NM
  5000 feet through 10,000 feet MSL — 120 feet per NM
  10,000 feet MSL and over — 100 feet per NM

• Minimum Turning Altitude
– MTAs the published minimum enroute altitude (MEA) may not be sufficient for obstacle clearance when a turn is required over a fix, NAVAID, or waypoint.

– Pilots must ensure they are at or above the charted MTA not later than the turn point and maintain at or above the MTA until joining the centerline of the ATS route following the turn point. Once established on the centerline following the turning fix, the MEA/MOCA determines the minimum altitude available for assignment.

• Off Route Obstruction Clearance Altitude
– This route provides obstruction clearance with a 1,000-foot (non-mountainous) and 2,000-foot (mountainous areas)
– OROCAs are intended primarily as a pilot tool for emergencies and situational awareness
– This altitude may not provide signal coverage.

IFR Cruising Altitude & VFR-On-Top
– In controlled airspace, pilots must maintain the altitude assigned by ATC
– When operating with a VFR-on-top clearance, any VFR cruising altitude appropriate to the direction of flight that allows the flight to remain in VFR conditions
– Any change in altitude must be reported to ATC and pilots must comply with all other IFR reporting procedures
– VFR-on-top is not authorized in Class A airspace

Reporting Procedures
– These are reports that should be made without a specific request from ATC
• VFR-on-top change in altitude
• Missed approach
• Leaving one assigned flight altitude for another
• Leaving any assigned holding fix or point
• Unable to climb or descend at least 500 feet per minute
• TAS variation from filed speed of 5% or 10 knots, whichever is greater
• Time and altitude upon reaching a holding fix
• Loss of NAV/Comm capability
• Unforecasted weather conditions or other information relating to the safety of flight

Non RADAR Reports
– If radar contact has been lost the CFRs require pilots to provide ATC with position reports over designated VORs
• Compulsory reporting points as depicted on IFR en route charts by solid triangles
• Leaving FAF or OM inbound on final approach
• Revised ETA of more than three minutes

Position Report
– Identification – (CPF 1256)
– Position–(FILMS)
– Time–(1215z)
– Altitude/FlightLevel–(5000)
– ETA over the next reporting fix – (MATAN IN 5 MIN)
– Following reporting point–(VHP VORTAC)
– Pertinent remarks

§91.187 Operation under IFR in controlled airspace: Malfunction reports.

(a) The pilot in command of each aircraft operated in controlled airspace under IFR shall report as soon as practical to ATC any malfunctions of navigational, approach, or communication equipment occurring in flight.
(b) In each report required by paragraph (a) of this section, the pilot in command shall include the—
  (1) Aircraft identification;
  (2) Equipment affected;
  (3) Degree to which the capability of the pilot to operate under IFR in the ATC system is impaired; and
  (4) Nature and extent of assistance desired from ATC.

Approach Procedures

Weather Considerations
– Weather conditions generally determine which approaches can be used, or if an approach can even be attempted
– The primary concerns for approach decision-making are wind speed and direction, ceiling, visibility, and field conditions
– Wind speed and direction are factors because they often limit the type of approach that can be flown at a specific location

Approach Speed and Category
– Two other critical performance factors are: aircraft approach category and planned approach speed
– According to 14 CFR Part 97.3 (b), aircraft approach category is based on the landing speed (if not specified 1.3 VS0 at max gross weight)
– The categories are as follows:
• Category A: Speed less than 91 knots.
• Category B: Speed 91 knots or more but less than 121 knots.
• Category C: Speed 121 knots or more but less than 141 knots.
• Category D: Speed 141 knots or more but less than 166 knots.
• Category E: Speed 166 knots or more.

– An airplane is certified in only one approach category although a faster approach speed may be used
– If a faster approach speed is used the minimums for the appropriate higher category must be used

Circling Approaches
– An airplane cannot be flown to the minimums of a slower approach category
– Published circling minimums provide obstacle clearance only within the appropriate area of protection based on the approach category speed
– The circling approach area is the obstacle clearance area for airplanes maneuvering to land on a runway that does not meet the criteria for a straight-in approach
– A minimum of 300 feet of obstacle clearance is provided in the circling segment
– Pilots should remain at or above the circling altitude until the airplane is in a position from which a descent to a landing can be made

Chart Format – Chart Identification

– Procedures that allow a pilot to land straight in when conditions permit have a runway number in the chart identification

– Procedures without Straight-In Minimums have a letter after the type of approach

• Chart Format – Notes Section
– Non-Standard Takeoff Minimums, and Non- Standard Alternate Minimums
– Inoperative components

• Minimum Safe Altitude
– These are published for emergency use on IAP charts
– The MSA is normally based on the primary omnidirectional facility on which the IAP is predicated
– MSAs are expressed in feet MSL and normally have a 25NM radius

– Ideally, a single sector altitude is established and depicted on the planview of approach charts
– MSAs provide 1,000 feet clearance over all obstructions and may not have acceptable navigation signal coverage

• Chart Format – Vertical Navigation Information

• Chart Format – Vertical Guidance Approach Minimums

• Chart Format – Airport Sketch

Operations below DA, DH, or MDA
– No pilot may operate an aircraft below the MDA or the DH unless —

• (1) The aircraft must be in a position to make a normal landing straight in
• (2) The flight visibility is not less than the visibility prescribed in the approach procedure
• (3) At least one of the following visual references
– The threshold.
– The threshold markings
– The threshold lights
– The runway end identifier lights
– The visual approach slope indicator
– The touchdown zone or touchdown zone markings
– The touchdown zone lights
– The runway or runway markings
– The runway lights

– The approach light system only allow a pilot to descend 100 feet above the touchdown zone elevation using the approach lights as a reference

§91.175 Takeoff and landing under IFR.

(c) Operation below DA/ DH or MDA.… no pilot may operate an aircraft… below the authorized MDA or continue an approach below the authorized DA/DH unless—
  (i) The approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.
  (ii) The threshold.
  (iii) The threshold markings.
  (iv) The threshold lights.
  (v) The runway end identifier lights.
  (vi) The visual approach slope indicator.
  (vii) The touchdown zone or touchdown zone markings.
  (viii) The touchdown zone lights.
  (ix) The runway or runway markings.
  (x) The runway lights.

Visual Approaches
– A visual approach is an ATC authorization for an aircraft on an IFR flight plan to proceed visually to the airport – it is not an IAP
– Once pilots report the aircraft in sight, they assume the responsibilities for their own separation and wake turbulence avoidance
– Also, there is no missed approach segment
– It is authorized when the ceiling is reported or expected to be at least 1,000 feet AGL and the visibility is at least 3 SM
– Pilots must remain clear of the clouds at all times while conducting a visual approach

Instrument Landing Systems
– A system that allows an aircraft both vertical and horizontal guidance to land in IMC conditions

ILS Approach Categories
– There are three general classifications of ILS approaches — CAT I, CAT II, and CAT III
• CAT I — DH 200 feet and RVR 2,400 feet
• CAT II — DH 100 feet and RVR 1,200 feet
• CAT IIIa — No DH or DH below 100 feet and RVR not less than 700 feet
• CAT IIIb — No DH or DH below 50 feet and RVR less than 700 feet but not less than 150 feet
• CAT IIIc — No DH and no RVR limitation
– To date, no U.S. operator has received approval for CAT IIIc approaches

VOR Approach
– VOR approaches use VOR facilities both on and off the airport to establish approaches
– All VOR approaches are non-precision approaches, and can provide MDAs as low as 250 feet above the runway
– VOR also offers a flexible advantage in that an approach can be made toward or away from the navigational facility
– When DME is included in the title of the VOR approach, operable DME must be installed in order to fly the approach

NDB Approach
– NDB approach can be designed using facilities both on and off the airport
– For the NDB to be considered an on-airport facility, the facility must be located within one mile of any portion of the landing runway

Localizer Approaches
– Typically, when the localizer is discussed, it is thought of as a nonprecision approach
– A localizer is always aligned within 3 degrees of the runway, and it is afforded a minimum of 250 feet obstacle clearance in the final approach area

Localizer Back Course
– In cases where an ILS is installed, a back course may be available in conjunction with the localizer
– The localizer approach system can provide both precision and nonprecision approach capabilities to a pilot
– In either case, the localizer provides an on precision approach using a localizer transmitter installed at a specific airport
– The back course does not offer a glide slope and it can project a false glide slope signal and should be ignored
– Reverse sensing will occur on the back course using standard VOR equipment

Equipment Problems • Communication Failure

– Two-way radio communication failure procedures for IFR operations are outlined in 14 CFR Part 91.185
– Pilots can use the transponder to alert ATC to a radio communication failure by squawking code 7600
– If only the transmitter is INOP, listen for ATC instructions on any operational receiver (This could also be any VOR, VOR / DME, VORTAC, ILS, or NDB frequency)
– If the radio fails in VFR conditions, continue the flight under VFR conditions and land as soon as practicable

– If pilots must continue their flight under IFR conditions after experiencing two-way radio communication failure, they should fly one of the following routes:
• 1.) The route assigned by ATC in the last clearance
• 2.) If being radar vectored, the direct route from the point of radio failure to the fix, route, or airway
• 3.) The route ATC has advised to expect in a further clearance
• 4.) The route filed in the flight plan.

– The altitude to fly after a communication failure can be found in Part 91.185
• The altitude in the last ATC clearance.
• The minimum altitude for IFR operations.
• The altitude ATC has advised to expect

§91.185 IFR operations: Two-way radio communications failure.

(a) General. Unless otherwise authorized by ATC, each pilot who has two-way radio communications failure when operating under IFR shall comply with the rules of this section.
(b) VFR conditions. If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the flight under VFR and land as soon as practicable.
(c) IFR conditions. If the failure occurs in IFR conditions, or if paragraph (b) of this section cannot be complied with, each pilot shall continue the flight according to the following:
  (1) Route. (i) By the route assigned in the last ATC clearance received;
  (ii) If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance;
  (iii) In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance; or
  (iv) In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.
(2) Altitude. At the highest of the following altitudes or flight levels for the route segment being flown:
  (i) The altitude or flight level assigned in the last ATC clearance received;
  (ii) The minimum altitude (converted, if appropriate, to minimum flight level as prescribed in §91.121(c)) for IFR operations; or
  (iii) The altitude or flight level ATC has advised may be expected in a further clearance.
(3) Leave clearance limit. (i) When the clearance limit is a fix from which an approach begins, commence descent or descent and approach as close as possible to the expect-further-clearance time if one has been received, or if one has not been received, as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
  (ii) If the clearance limit is not a fix from which an approach begins, leave the clearance limit at the expect-further-clearance time if one has been received, or if none has been received, upon arrival over the clearance limit, and proceed to a fix from which an approach begins and commence descent or descent and approach as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.

Checkride Videos

February 8th, 2017

I ran across this video by Andy Munnis and it’s full of interesting stuff about the oral portion of the checkride.

This is the AIM Cold Temperature Error Table that he references in the talk. And the Fort Collins Departure Procedure.

Fort Collins DP

Note the minimum turning altitudes (MTA) at Allan.

Allan Interesction

This FAA presentation has lots of good stuff you need to know for your checkride—and when flying IFR.

Andy also has a private pilot checkride video.

The first part of an IFR checkride is the oral. It shouldn’t be difficult to pass if you know the basics of instrument planning. The John at FLY8MA.com Flight Training goes through a simulated oral with a DPE.

Jason at MZAero has lots of videos that are pretty good. Here he is doing an interactive video that has lots of good stuff interspersed with giveaways and irrelevant chatter. He’s an acquired taste and this is mostly an ad for his checkride prep courses but probably worth investing the hour, especially if you skip the annoying stuff and maybe give up at the halfway point.

Here’s another DPE discussing the PTS and how it applies to the instrument checkride.

I haven’t had a chance to watch these yet, but given the content in her instrument video, I suspect that they’ll be informative but dull.

I’ll add more videos as I run across them.

IFR Alternate Airport Minimums

February 8th, 2017

The TPP has a section containing alternate minimums for approaches. It starts off with this paragraph.

Standard alternate minimums for non-precision approaches and approaches with vertical guidance [NDB, VOR, LOC, TACAN, LDA, SDF, VOR/DME, ASR, RNAV (GPS) or RNAV (RNP)] are 800-2. Standard alternate minimums for precision approaches (ILS, PAR, or GLS) are 600-2. Airports within this geographical area that require alternate minimums other than standard or alternate minimums with restrictions are listed below. NA – means alternate minimums are not authorized due to unmonitored facility, absence of weather reporting service, or lack of adequate navigation coverage. Civil pilots see FAR 91. IFR Alternate Minimums: Ceiling and Visibility Minimums not applicable to USA/USN/USAF. Pilots must review the IFR Alternate Minimums Notes for alternate airfield suitability.

The first part is straightforward. In order to use an approach as an alternate when filing an IFR flight plan, the visibility has to be 2 statute miles and the ceiling has to be 800′ AGL if the approach is non-precision. It has to be 2 statute miles and the ceiling has to be 600′ AGL for precision approaches. If the minimums are different for an approach then the non-standard minimums are listed. They can be things like NA when control tower closed. or NA when local weather not available. as well as increased visibility and ceiling. The minimums are specific to each approach.

Alternate Minimums

What confused me is the NA notation. When I first saw it on the chart, I assumed that the approach was not available as an alternate. But when I read the note above, NA – means alternate minimums are not authorized due to unmonitored facility, absence of weather reporting service, or lack of adequate navigation coverage. I was a bit confused. Does it mean that alternate minimums are not available and you can use standard minimums? Or does it mean that no alternate minimums apply to this approach, therefore it can’t be used as an alternate.

It turns out that what it means is that the approach is not available to be used as an alternate when filing an IFR flight plan. If there is another approach that is available for use as an alternate, and the pilot needs to fly to the airport, the approach can be flown if the approach minimums are met at the time of arrival. Andy Munnis explains it well (beginning at the 51 minute mark):

Minimum Turning Altitude (MTA)

February 8th, 2017

I was watching a video by Andy Munnis and he talked about a fix outside of Denver that has a fairly lengthy list of MTAs. I had never heard of them before so I pulled up the chart to see what he was talking about.

MTA ALLAN

At first glance the altitudes don’t make any sense. Most of them are higher than the MEA on the airway that the pilot is turning onto. So I resorted to searching for an explanation.

Based on this Charting Notice, I think they are a recent addition to the IFR charts.

Due to increased airspeeds at 10,000 ft MSL or above, the published Minimum Enroute Altitude (MEA) may not be sufficient for obstacle clearance when a turn is required at a Fix, NAVAID, or Waypoint. In these instances, the area in the vicinity of the turn point is evaluated to determine whether the published MEA is sufficient for obstacle clearance.

In some locations (normally mountainous), terrain/obstacles in the expanded search area may necessitate a higher minimum altitude while conducting the turning maneuver. A Fix, NAVAID, or Waypoint requiring a higher Minimum Turning Altitude (MTA) will be denoted on government charts by the Minimum Crossing Altitude (MCA) icon (“X” flag) and an accompanying note describing the MTA restriction. An MTA restriction note will normally consist of the Air Traffic Service (ATS) route leading to the turn point, the ATS route leading from the turn point, and the required altitude; e.g., MTA V330 E TO V520 W 16000. When an MTA is applicable for the intended route of flight, pilots must ensure they are at or above the charted MTA not later than the turn point and maintain at or above the MTA until joining the centerline of the ATS route following the turn point.

When we look at the terrain to the northwest of ALLAN, we see that it rises sharply. Given the explanation above, that’s probably how they came up with the minimum altitudes for turning aircraft.

MTA ALLAN VFR

The first sentence in the Charting Notice starts with, Due to increased airspeeds at 10,000 ft MSL or above. This is just a reference to the elimination of the speed restriction for aircraft flying at 10,000 MSL and above. In the case of the ALLAN intersection, all of the MEAs are well above 10,000′ MSL.

Here’s a new MTA where the intersection is very busy and it might be easy to miss the MTA, especially since V187 (which crosses POM an goes to HASSA) has an MEA of 6,500 between POM and HASSA and an MCA of 10,000 at HASSA. The MTA of 11,800 is somewhat unexpected.

MTA POM

It should be pointed out that ATC will be assigning aircraft on these routes altitudes and speeds so the MTAs and MCAs will not be an issue. They are only an issue for pilots in the case of lost communications.

I looked at a Jeppesen chart from 24DEC10 and there is no MTA at ALLAN and the 16APR10 chart containing POM has no MTA either. So that reinforces the inference that the Chart Notice is the introduction of the concept.

The information in the Charting Notice has been incorporated into the AIM.
AIM 5−3−7. Minimum Turning Altitude (MTA)

Due to increased airspeeds at 10,000 ft MSL or above, the published minimum enroute altitude (MEA) may not be sufficient for obstacle clearance when a turn is required over a fix, NAVAID, or waypoint. In these instances, an expanded area in the vicinity of the turn point is examined to determine whether the published MEA is sufficient for obstacle clearance. In some locations (normally mountainous), terrain/obstacles in the expanded search area may necessitate a higher minimum altitude while conducting the turning maneuver. Turning fixes requiring a higher minimum turning altitude (MTA) will be denoted on government charts by the minimum crossing altitude (MCA) icon (“x” flag) and an accompanying note describing the MTA restriction. An MTA restriction will normally consist of the air traffic service (ATS) route leading to the turn point, the ATS route leading from the turn point, and the required altitude; e.g., MTA V330 E TO V520 W 16000. When an MTA is applicable for the intended route of flight, pilots must ensure they are at or above the charted MTA not later than the turn point and maintain at or above the MTA until joining the centerline of the ATS route following the turn point. Once established on the centerline following the turning fix, the MEA/MOCA determines the minimum altitude available for assignment. An MTA may also preclude the use of a specific altitude or a range of altitudes during a turn. For example, the MTA may restrict the use of 10,000 through 11,000 ft MSL. In this case, any altitude greater than 11,000 ft MSL is unrestricted, as are altitudes less than 10,000 ft MSL provided MEA/MOCA requirements are satisfied.

Introduction to the ATC System & National Airspace System

February 7th, 2017

I found this link when looking for something else and thought it was worth sharing. It gives a good overview of the different roles and responsibilities of the people in the ATC system.


The content on this web site is provided for your information only and does not purport to provide or imply legal advice.
Should opinions, explanations, or discussions conflict with current FARs, other rules, regulations, or laws, then appropriate provisions of those rules, regulations, or laws prevail.
Navigation charts are provided for illustrative purposes only and are Not for Navigation.
TouringMachine.com is not responsible or liable for any errors, omissions, or incorrect information contained within this site.
Use at your own risk.
Copyright © 2002-2022 Touring Machine Company. All Rights Reserved.