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Interesting Winds Today

September 19th, 2017

Checking out the hurricanes on Earth Wind Map I happened to notice two lows in the Pacific.

Earth Wind Map

Communications with ATC

September 17th, 2017

A recent forum post asked about the correct way to contact ATC. Specifically, they had heard that pilots use their aircraft type and color. I think they were confusing communication with ATC and talking to other pilots at a non-towered airport.

The AIM discusses communications with ATC in Chapter 4.

4−2−3. Contact Procedures
a. Initial Contact.
1. The terms initial contact or initial callup means the first radio call you make to a given facility or the first call to a different controller or FSS specialist within a facility. Use the following format:

(a) Name of the facility being called;
(b) Your full aircraft identification as filed in the flight plan or as discussed in paragraph 4−2−4, Aircraft Call Signs (below);
(c) When operating on an airport surface, state your position.
(d) The type of message to follow or your request if it is short; and
(e) The word “Over” if required.

c. Subsequent Contacts and Responses to Callup from a Ground Facility. Use the same format as used for the initial contact except you should state your message or request with the callup in one transmission.

4−2−4. Aircraft Call Signs
2. ATC specialists may initiate abbreviated call signs of other aircraft by using the prefix and the last three digits/letters of the aircraft identification after communications are established.

…The pilot may use the abbreviated call sign in subsequent contacts with the ATC specialist.

When operating at a non-towered field, many pilots have begun to identify their aircraft by type and color. I’m not sure when this started, but if you listen to popular YouTube flyers like steveo1kinevo, you will notice that when they are flying into non-towered fields, they just give the aircraft type, e.g. Caravan or TBM. From a practical standpoint, it makes a lot of sense. You can’t see the numbers but you can see the type and color. And unless there are lots of white Cessnas in the pattern, it is easy to keep track of who is where. What you want to know in the pattern is where are the other planes and how fast are they going.

Type and color gives you the necessary information. For me at least, it is easier to keep track of type and color than it is to keep track of N numbers.

Flying with an HSI

September 12th, 2017

My brother just got a Piper Arrow with a Sandel 3308 HSI. I can’t find any videos on how to use the 3308, but there are lots on how to use an HSI. These are some of the best.

For those of you who like to read, rather than watch an explanation, this Introduction to HSIs is a good start.

This video explains how to use the setup to figure out how VORs and HSIs work. Lots of tricks to figure out where you are based on the TO/FROM indicator and the location of the needle. For some reason, I never ran across these tricks before, but they are quite handy.

If you don’t have a sim, you can check out the basics of an HSI on the website from Luiz Monteiro that was references in the above video. Nav Sim (Requires Flash). Be sure to check out the instructions so you can see which keys move the wings.

There are lots of HSI questions on the writtens, and most of them have no relation to real-world flying. Here’s a video that helps explain how to answer these questions.

Touch and Goes

July 31st, 2017

In primary training, touch-and-goes do not reflect reality. In the world we are preparing student pilots to enter, airplanes take off, go somewhere (even if it is the pattern) and return to land. The goal of getting a pilot certificate is to be able to travel by air rather than on the ground. Accordingly, for primary students the takeoff and climb to pattern altitude and the approach to land are different things and should not be conflated. After I got my CFI head screwed on properly I had students land to a full stop, at which time I took over the controls to taxi back to the departure end. During that time I could discuss the most recent landing and the student could assimilate what I was saying without having to divide his/her attention between listening to me and taxiing. The human brain can assimilate a limited number of simultaneous inputs, so why push it??

Bob Gardner

Bob’s view is in line with mine. One of the first things I learned when taking lessons is that you need to Fly the airplane all the way to the hangar. If you do touch and goes, you aren’t practicing techniques that you will use later.

I learned to fly in a 182 so there is a lot going on when you land. The 182 requires a lot of trim, is fairly heavy and has huge 40° flaps so it sinks like a rock, and it has a powerful engine that needs a lot of right rudder. To do a touch and go, you need to reach down to open the cowl flaps, hold the flap lever up for 10 seconds, verify that the flaps retracted, check that you remembered to push the prop in, give it power while also giving it right rudder, and then watch your airspeed while moving quickly down the runway. I don’t process things that fast so I always felt that I was behind the plane. When we got the Cessna 210, you had all of the same issues with a much heavier and more powerful plane. It still has electric flaps, but you can move them to the detent so it is easier to select 10° of flaps for takeoff. Slowing it down to make the turnoff requires that you stick the landing and landing speed. I have done touch and goes in the 210, but I really want to practice complete energy management, so I always do taxi-backs. Like Bob said, it gives me time to evaluate the last landing and go through my pre-takeoff checklist.

CFI is acting as PIC

July 27th, 2017

In a footnote to Administrator v Strobel, the NTSB states:

Our precedent makes clear that, “[r]egardless of who is manipulating the controls of the aircraft during an instructional flight, or what degree of proficiency the student has attained, the flight instructor is always deemed to be the pilot-in-command.” Administrator v. Hamre, 3 NTSB 28, 31 (1977). This principle was reaffirmed in Administrator v. Walkup, 6 NTSB 36 (1988).

THE PILOT IN COMMAND AND THE FARS: THE BUCK STOPS HERE (ALMOST ALWAYS) has some other examples of determining who is PIC.

Captain Warren VanderBurgh

July 20th, 2017

He combines lessons learned from accidents as well as trying things out in the simulator to explain lots of good techniques that apply to GA pilots as well as those flying big jets.

Children of the Magenta Line

Unusual Attitude Recovery

Windshear and Microburst Review

CFIT – Advanced Aircraft Maneuvering Program

Control Malfunctions & Flight Instrument Anomalies

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

July 7th, 2017

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).

ForeFlight has an enhanced radar feature that you can turn on to show cloud cover. It doesn’t show the depth of the clouds or the tops, but you can use it to see where the nearest VFR conditions are. Along the central coast, it usually shows how far inland the fog is. In the summer in the midwest, it can show widespread cloud cover. This image shows that there is widespread IFR to the east with a pocket of VFR down the left side. Here’s a smaller version.

IFR Flight Deviation

Suppose you have three hours to go on an IFR flight and you have crossed the Pioneer VOR and are approaching the MANON intersection when you lose radio communication. What do you do? The standard response is that you would maintain the highest of the Minimum IFR Altitude, Expected Altitude, or Assigned Altitude and fly the Assigned, Vectored, Expected or Filed route. But is that the best thing to do? I would say no.

First, unless you know exactly what caused the comms failure, you could be setting yourself up for a bad outcome. Maybe the alternator belt is broken and lying lose in the cowl, but maybe it is rubbing agains the alternator and just about to catch fire. Or maybe you have a gear-driven alternator and the gears are being tossed around in the engine.

Second, how are you going to safely navigate the next three hours? If you still have nav functions, are they going to continue?

Third, how comfortable are you descending at your destination? What are the altitudes along the way?

Wouldn’t it make more sense to head west to VFR conditions? You can see from the chart that the Minimum IFR Sector Altitude is 3,400′. Climb to at least 4,000′ and head west or southwest to VFR conditions. Or turn around and go back where there were VFR conditions over Pioneer. That way you have less than a half hour in IFR. ATC should be able to track you, and if you go in a reasonable straight line, they will be able to keep other IFR traffic away from you. If you know the cloud tops, and have a capable aircraft, you might be able to climb to VFR on top and then you can do your own traffic avoidance.

When are you established on the approach?

June 30th, 2017

I’ve been doing a lot of practice approaches lately and if a procedure turn (or hold) is required, they tell me to ‘report procedure turn (hold) inbound’. Then they clear me for the approach. I think this is why:

AIM 5−4−7. Instrument Approach Procedures

b. When operating on an unpublished route or while being radar vectored, the pilot, when an approach clearance is received, must, in addition to complying with the minimum altitudes for IFR operations (14 CFR Section 91.177), maintain the last assigned altitude unless a different altitude is assigned by ATC, or until the aircraft is established on a segment of a published route or IAP. After the aircraft is so established, published altitudes apply to descent within each succeeding route or approach segment unless a different altitude is assigned by ATC. Notwithstanding this pilot responsibility, for aircraft operating on unpublished routes or while being radar vectored, ATC will, except when conducting a radar approach, issue an IFR approach clearance only after the aircraft is established on a segment of a published route or IAP, or assign an altitude to maintain until the aircraft is established on a segment of a published route or instrument approach procedure. For this purpose, the procedure turn of a published IAP must not be considered a segment of that IAP until the aircraft reaches the initial fix or navigation facility upon which the procedure turn is predicated.

IFR Checkride—Flight Prep

June 29th, 2017

For the IFR checkride the local examiner has you plan a few flights. He gives the destinations in advance and on the day of the checkride you use current weather or he gives you the weather at each destination. The exercise tests your ability to plan alternates, check for icing along the route, and know whether your aircraft can actually fly the approaches and the missed approach. Hint: a Cessna 172 would have trouble flying the missed on a hot day in Tahoe but my Turbo Cessna 210 would not have an issue on most days.

ForeFlight is really good at showing routes using Victor airways and recently cleared routes. You do need to pay attention to the altitudes on longer distances since many of the cleared routes are for jets or turboprops. If you have more than the basic subscription, you can also get a profile view so you can check that your planned altitude is more than 2,000′ above obstacles.

Santa Maria to Paso Robles
KSMX GLJ MQO V113 PRB RNAV (GPS) RWY 19 KPRB 5000ft⁩ 90nm

The trick on this one is the departure. Paso Robles is Northwest of Santa Maria and the only departure procedure has you flying 22 miles southeast of the airport, making a U-turn and flying back to the Guadalupe VOR (just 4nm NW of the takeoff runway). However, there is a departure procedure that takes you directly to the GLJ terminal VOR and from there to MQO.

Rwy 2, climbing left turn;
Rwy 12, climbing left turn (do not exceed 230 KIAS until established northwest bound to GLJ VOR).
Rwy 30, climb heading 294°.

All aircraft: climb direct GLJ VOR, then continue climb to airway MEA via GLJ R-300 to intercept MQO R-137 to MQO VORTAC. Cross MQO VORTAC at or above MEA/ MCA for assigned route of flight.

You can play around with ForeFlight to get an idea of where you will intercept the MQO R-137 and it is at around 5nm. (Hint: Add GLJ/300/5 between GLJ and MQO on your flight plan and note that your course from there to MQO is 318°M.)

The approach with the lowest minimums is RNAV RWY19 and that is the no-wind runway, so we’ll plan for that. The approach starts at the airport at 4,700 MSL, proceeds outbound, and has a procedure turn.

There is no approach lighting, but there is a REIL and MIRL runway lighting.

An interesting feature of the approach plate is that there are two feeder routes (there is an altitude, direction, and distance). FIKDU and NEFDE are IAFs that are on airways and the chart show you how to get to the intermediate fix (HOVLI) from there.

There aren’t any other airports nearby, so KSBP or a return to KSMX would be your best bet for alternates.

Paso Robles to Harris Ranch
KPRB V113 ROM 3O8 7000ft 50nm

When you see this symbol AlternateTakeoffMinimums on the approach plate, it means that either there are non-standard takeoff minimums or that there is a published departure procedure. All of the approaches have the AlternateTakeoffMinimums. There are no SIDS at KPRB, so we look in the TPP for obstacle departure procedures.

DEPARTURE PROCEDURE: All departures maintain 250 kts or less until inbound to PRB. …

Rwy 19, climb to 3000 via heading 150° to intercept PRB R- 179 outbound. V113 southbound continue climb on course. All others climbing left turn to 4500 direct PRB.

Rwy 1, climb to 3000 via heading 280° to intercept PRB R-326 outbound. V248 northbound climb on course. All others climbing right turn to 4500 direct PRB.

Harris Ranch does not have an instrument procedure so an alternate is required. The only good alternate is to return to KPRB and there are no restrictions applicable to us on RNAV (GPS) Rwy 19 approach.

RNAV (GPS) Rwy 191
RNAV (GPS) Rwy 312,3
VOR Rwy 191

1 Category D, 900-3.
2 NA when local weather not available.
3 Category D, 900-3.

Because it does not have an instrument approach, the ceiling and visibility minima are those allowing descent from the MEA, approach, and landing under basic VFR.

V113 from PRB to ROM has an MEA of 6,000′. The Grid MORA at Harris Ranch is 7,600′. However, if we look at the VFR charts, we see that the highest point from ROM to 3O8 is is no higher than 4,000′. The profile view shows that 3,950 is the highest elevation. If we stay at 7,000′ from ROM to 3O8 until 10 miles from the airport we should have plenty of room to spare. 3O8 is in Class G airspace so the VFR minimums are 1 mile and COC. There are some antennas around the airport, so we would want to have higher minimums if we were not familiar with the area.

The runway at Harris Ranch is only 2,820′ long and there are obstacles, so you would want to make sure your aircraft is capable of taking off, especially if you have a full load on a hot day—which it often is in the valley.

Harris Ranch to Lake Tahoe

Alternative using T-Routes

Because there is no approach into Harris Ranch, there is no departure procedure. We are responsible for our own terrain clearance until reaching the Minimum IFR Altitude.

Harris Ranch Departure
I’d follow the runway heading for 4nm to clear the towers near the airport, then follow the freeway for another 20 miles before turning to Panoche. This route is completely flat, and you won’t hit anything before ATC will start vectoring you.

According to the Legal Interpretation in the Lamb inquiry, “takeoff into clouds without an ATC clearance or release was’extremely dangerous’ and in violation of section 91.13(a)” so you will need to file a flight plan and get a void time before you take off if conditions are below VFR.

As an aside, I was flying a practice approach using the RNAV 29 approach into KSBP and flew over Oceano (L52)—an airport with no appraches. It was clear everywhere except over the airport and immediate coast. An aircraft on the ground was asking for and IFR clearance to climb through a layer that was probably at 700′ and less than 1,000′ thick. I was listening for probably 10 minutes and the controller was working on getting a clearance, but didn’t get one in the time I was listening. I think that they didn’t get the clearance while I was listening because the controller was trying to get a clearance all the way to Hawthorne, when they really just needed a clearance to VFR on top.

Picking up you flight plan might be difficult. Rancho Murieta Flight Service can receive on 122.1 and transmit on the VOR 112.6 but the VOR is in the hills, so you might not be able to contact them. If you can’t contact them, you can call Clearance Delivery on 888-766-8267 to get a void time. Alternatively, if the weather is VFR you can depart and pick up your clearance before entering IMC. You are probably in Lemoore Approach airspace on 118.15 but it might be Oakland Center on 128.7.

You are 900′ above the runway at the MAP. You have 2.6 nm to descend 900′, so you really need to have the runway in sight before the MAP to comfortably make a descent to a landing on the intended runway at a normal rate of descent using normal maneuvers. (At 90kts, you are moving at 1.5nm per minute. That’s 1.7 minutes so you need to descend at 523 fpm.)

The missed approach requires a climbing right turn from 7,160′ to 12,000′ and holding at HETRY. That might be beyond the climb capabilities of many training aircraft when the weather is warm. You are over the lake so the climb rate isn’t too important, just whether you can actually climb that high. But since you made it from SWR to HETRY on the way in at 12,000′, you should be able to make it on the way out since you have 20 miles to do it in and the terrain around HETRY is less than the missed approach height.

Lake Tahoe to Van Nuys

KTVL SHOLE2.SPOOK 38.42523N/120.52736W FRA TTE AMONT LHS.LYNXX8 Vectors to Final ILS Z RWY 16R KVNY 9000ft 352nm

AMDT 7 15008 (FAA)
Rwy 18, std. w/min. climb of 804’ per NM to 11500, or 1600-3 w/min. climb of 741’ per NM to 11500, or 5000-3 for climb in visual conditions.
Rwy 36, 300-1 1⁄4 or std. w/min. climb of 269’ per NM to 6500.

DEPARTURE PROCEDURE: Rwy 18, climb heading 177° to 7900 then climbing right turn to intercept and climb on SWR R-133 to SWR VOR/DME thence …
Rwy 36, climb heading 357° to intercept and climb on SWR R-113 to SWR VOR/DME thence …
… proceed on course.

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.

NOTE: [Lots of obstacles]

There are two interesting things about the departure procedures. First, the required climb rate for a Rwy 18 takeoff is rather steep—remember that a standard instrument departure climb is 200 fpnm. And second, it has a VOCA (Visual Climb Over Airport) departure procedure.

The back cover of the TPP has Climb/Descent Table that gives the climb rate in feet per minute required for various fpnm climbs at various ground speeds. At 90 kts groundspeed, we’d need to be climbing at 1,200 feet per minute—and that’s from a starting altitude of 6,254′. Fortunately, departing over the lake the climb rate is only 269 fpnm (400 feet per minute at 90 kts), which is doable in many turbocharged aircraft like my C210.

The Visual Climb Over Airport departure procedure is one of the five IFR departure procedures but it is not very common—in fact this is the only one I’ve seen.

The SHOLE.TWO Departure requires a climb to 9,000′ at 300 fpnm and has an MEA of 15,000′. It is a bit shorter than the ODP for departures to the south, so if your airplane can do it, it would be slightly faster.

There is a 30nm segment where the MEA is 15,000′. The regulations require that crew members use oxygen any time they are above 14,000′ so oxygen would be required for the pilot and recommended (but not required) for passengers. The recommended altitude for using oxygen at night is 5,000′ and 10,000′ during the day.

The approach into Van Nuys is a little complicated. You’d most likely get vectors-to-final but for the exercise, he wants you to plan for the LYNXX.EIGHT arrival which takes you from Lake Hughes VOR to LYNXX and then the Van Nuys VOR.

From over LYNXX INT via VNY R-329 to VNY VOR/DM E. Expect radar vectors to final approach course after VNY VOR/DME.

For this approach, assume that you lost comms on the arrival and were going to use the ILS Z RWY 16R approach approach since it has the lowest DA. However, if you read the notes, RADAR is required, so if yo lost comms, that would not be a viable option and you would need to use the ILS Y RWY 16R approach. They are identical until DA. The ILS Y approach has a higher DA and a different missed approach procedure.

So how do you get to the approach from the VOR? You fly the feeder route to ZIDOM.

For lost comms, you fly the highest of the Minimum IFR Altitude, expected altitude, or assigned altitude. If you were flying at an assigned altitude of 9,000′ and lost comms before Lake Hughes, you could not descend to 7,000′ at Lake Hughes and 6,000′ at LYNXX. The only way you can descend to those levels is if you were told to “Descend via the LYNXX.EIGHT arrival, Lake Hughes transition.” and if you lost comms before that clearance, you could not descend. You could start your descent when flying from the VOR to ZIDOM because you are on the approach.

Whiteman to Long Beach

then V394—ADAMM to POWUP to AHEIM turning on V394 at AHEIM to SLI.

If you are looking at the paper copy of the TPP you may not find Whiteman since it is located under LOS ANGELES, CA (CON’T) for some reason.

ORIG 94034 (FAA)
TAKEOFF MINIMUMS: Rwys 12, 30, 2900-2 or std. with a min. climb of 350′ per NM to 4300.

Rwy 12, climbing right turn direct VNY VOR/DME.
Rwy 30, climbing left turn heading 260°. All aircraft climb to 4500 via VNY R-325, then climbing left turn direct VNY VOR/DME.

The examiner wants you to assume the winds favor Rwy 30. For IFR departures, climb to 400′ before starting any turns, in ForeFlight I used 1/2 mile from the airport before turning and intercepting the VNY 325 radial at about 3 miles. This gives a heading of 262°. Close enough to visualize the route you will fly.

KWHP Obstacle Departure

Northern and Southern California have TEC routes. Within the national airspace system it is possible for a pilot to fly IFR from one point to another without leaving approach control airspace. This is referred to as “Tower Enroute” which allows flight beneath the enroute structure. Most of us will not be flying jets or turbo-props, so our aircraft classification code will be either (P) =Non-jet (cruise speed 190 knots or greater) or(Q) =Non-jet (cruise speed 189 knots or less).

We need to look at flights in the Burbank area.

BURN19, BURN24, and BURN25 go to Long Beach. However, only BURN19 is a P or Q route.

LGB FUL SLI TOA………………………………BURN19
V186 ADAMM V394 SLI …………………….. PQ50

The altitude is 5,000′.

Lost Comms
Let’s use the ILS or LOC RWY 30 approach into Long Beach. So how do you get from SLI to an IAF? GUNEY is right next to the VOR and there is a feeder route (2,000′, 196°, 2nm) from SLI to GUNEY. The intercept angle to the ILS is greater than 90° so you would need to fly the hold to do a course reversal.


If you lost comms before SLI, you would need to stay at 5,000′ until SLI (even though the MEAs are lower—remember its the highest of MIA, expected, or assigned—and then you could begin your descent because you would be established on the Instrument Approach Procedure.

Under lost comms, to fly the approach into Long Beach you need to get from SLI to an IAF. the RNAV (GPS) Z RWY 30 approach has an FAF at GUNEY but there is no way to get there from SLI. If the GPS approaches had TAAs instead of MSAs we could probably use them, but they don’t. The RNAV (RNP) approaches don’t apply to us. We could do the VOR or TACAN RWY 30 approach, since it starts at SLI. The minimums are 640/50 which is worse than the 258/18 for the ILS, but if the weather is good, it would be fine.

Long Beach to Camarillo


AMDT 6 16147 (FAA)
TAKEOFF MINIMUMS: Rwy 25L/R, std. w/min. climb of 225’ per NM to 2300.

Rwy 7L/R, climb heading 076° to 800, then climbing right turn SLI VORTAC and to SLI R-210 to PADDR INT.
Rwy 12, climb heading 121° to intercept SLI VORTAC R-210 to PADDR INT.

Rwy 25L/R, climb heading 256° to 800, then climbing left turn heading 200° and LAX VORTAC R-145 to PADDR INT.
Rwy 30, climb heading 301° to 800, then climbing left turn heading 200° and lax VORTAC R- 145 to PADDR INT.
NOTE: (Lots of obstacles)

Rwys 7L/R, 12, 30, heading as assigned by ATC.
Rwy 25L, heading as assigned by ATC; requires minimum climb of 330’ per NM to 700.
Rwy 25R, heading as assigned by ATC; requires minimum climb of 230’ per NM to 1600.

You’ll probably be given radar vectors from Rwy 25L or 25R, since the obstacle departure procedures take you way out of your way to PADDR. You might be given a partial obstacle departure, since you TEC route starts at SLI and the departure procedures for 7L/R and 12 have SLI as a fix.

IF you have WAAS, you can start the approach at SUANA for the RNAV (GPS) Z RWY 26 and get down to 327 for a DA. If you are GPS equipped but not WAAS enabled, then you would need to use the RNAV (GPS) Y RWY 26 approach. If no GPS, then you could use the VOR RWY 26 and start your approach at the VNY VOR. Minimims are 1100/1 1/4.

An alternate is always required for flights to airfields without an instrument approach like Harris Ranch. Otherwise, it depends on the weather. I’ll cover them in a separate post.

Takeoff and Landing
§91.103 Preflight action.
(b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

There are two airports on these flights where that might be a concern, Harris Ranch, because it is short, and Lake Tahoe, because of its elevation. I’ll cover them in a separate post.

Feeder Routes

June 28th, 2017

Sometimes when you look at an approach chart, you see fixes that are labeled as IAF but have a gap between the arrow and the next fix (usually an IF).

For example, FIKDU on the KPRB RNAV RWY19 does not have a continuous arrow leading to the approach. However, it does have an altitude, direction, and distance so you can fly from FIKDU to MEETL.

It gets more complicated on the ILS Y RWY 16R approach. Notice that there are three arrows going from the Filmore VOR to the localizer. Only one of them is flyable. The other two are cross radials used to identify the JINAT and FURRY intersections. The R-235 radial from Van Nuys looks like it is a cross radial used to identify ZIDOM, but it is also flyable since there is an altitude, direction, and distance to ZIDOM labeled near the VOR.

If you are flying the LYNXX.EIGHT arrival it would take you to the VNY VORTAC. So how do you get to the approach from the VOR? You fly the feeder route to ZIDOM—an IAF.

Things to Remember IFR Checkride—Abbreviations

June 19th, 2017

INSTRUMENT FLIGHT RULES A set of rules governing the conduct of flight under instrument meteorological conditions

INSTRUMENT METEOROLOGICAL CONDITIONS Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions.

INSTRUMENT DEPARTURE PROCEDURE A preplanned instrument flight rules (IFR) departure procedure published for pilot use, in graphic or textual format, that provides obstruction clearance from the terminal area to the appropriate en route structure. There are two types of DP, Obstacle Departure Procedure (ODP), printed either textually or graphically, and Standard Instrument Departure (SID), which is always printed graphically.

STANDARD TERMINAL ARRIVAL A preplanned instrument flight rules (IFR) air traffic control arrival procedure published for pilot use in graphic and/or textual form. STARs provide transition from the en route structure to an outer fix or an instrument approach fix/arrival waypoint in the terminal area.

INSTRUMENT APPROACH PROCEDURE A series of predetermined maneuvers by reference to flight instruments with specified protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if a landing is not completed, to a position at which holding or en route obstacle clearance criteria apply.

MINIMUM IFR ALTITUDES (MIA) Minimum altitudes for IFR operations as prescribed in 14 CFR Part 91. These altitudes are published on aeronautical charts and prescribed in 14 CFR Part 95 for airways and routes, and in 14 CFR Part 97 for standard instrument approach procedures. If no applicable minimum altitude is prescribed in 14 CFR Part 95 or 14 CFR Part 97, the following minimum IFR altitude applies:
a. In designated mountainous areas, 2,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown; or
b. Other than mountainous areas, 1,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown; or
c. As otherwise authorized by the Administrator or assigned by ATC.

MINIMUM EN ROUTE IFR ALTITUDE The lowest published altitude between radio fixes which assures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes. The MEA prescribed for a Federal airway or segment thereof, area navigation low or high route, or other direct route applies to the entire width of the airway, segment, or route between the radio fixes defining the airway, segment, or route.

MINIMUM OBSTRUCTION CLEARANCE ALTITUDE (MOCA) The lowest published altitude in effect between radio fixes on VOR airways, off-airway routes, or route segments which meets obstacle clearance requirements for the entire route segment and which assures acceptable navigational signal coverage only within 25 statute (22 nautical) miles of a VOR.

a. The minimum altitude specified in 14 CFR Part 91 for various aircraft operations.
b. Altitudes depicted on approach charts which provide at least 1,000 feet of obstacle clearance for emergency use. These altitudes will be identified as Minimum Safe Altitudes or Emergency Safe Altitudes and are established as follows:
1. Minimum Safe Altitude (MSA). Altitudes depicted on approach charts which provide at least 1,000 feet of obstacle clearance within a 25-mile radius of the navigation facility, waypoint, or airport reference point upon which the MSA is predicated. MSAs are for emergency use only and do not necessarily assure acceptable navigational signal coverage.
(See ICAO term Minimum Sector Altitude.)
2. Emergency Safe Altitude (ESA). Altitudes depicted on approach charts which provide at least 1,000 feet of obstacle clearance in nonmountainous areas and 2,000 feet of obstacle clearance in designated mountainous areas within a 100-mile radius of the navigation facility or waypoint used as the ESA center. These altitudes are normally used only in military procedures and are identified on published procedures as “Emergency Safe Altitudes.”

MINIMUM VECTORING ALTITUDE The lowest MSL altitude at which an IFR aircraft will be vectored by a radar controller, except as otherwise authorized for radar approaches, departures, and missed approaches. The altitude meets IFR obstacle clearance criteria. It may be lower than the published MEA along an airway or J-route segment. It may be utilized for radar vectoring only upon the controller’s determination that an adequate radar return is being received from the aircraft being controlled. Charts depicting minimum vectoring altitudes are normally available only to the controllers and not to pilots.

MINIMUM SECTOR ALTITUDE The lowest altitude which may be used under emergency conditions which will provide a minimum clearance of 300 m (1,000 feet) above all obstacles located in an area contained within a sector of a circle of 46 km (25 NM) radius centered on a radio aid to navigation.

MINIMUM CROSSING ALTITUDE The lowest altitude at certain fixes at which an aircraft must cross when proceeding in the direction of a higher minimum en route IFR altitude (MEA).

MAXIMUM AUTHORIZED ALTITUDE A published altitude representing the maximum usable altitude or flight level for an airspace structure or route segment. It is the highest altitude on a Federal airway, jet route, area navigation low or high route, or other direct route for which an MEA is designated in 14 CFR Part 95 at which adequate reception of navigation aid signals is assured.

MINIMUM TURNING ALTITUDE 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

MINIMUM RECEPTION ALTITUDE The lowest altitude at which an intersection can be determined.

CHANGEOVER POINT A point along the route or airway segment between two adjacent navigation facilities or waypoints where changeover in navigation guidance should occur.

OFF ROUTE OBSTRUCTION CLEARANCE AREA/MINIMUM OFF ROUTE ALTITUDE An off-route altitude which provides obstruction clearance with a 1,000 foot buffer in nonmountainous 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 navigational aids, air traffic control radar, or communications coverage.

FINAL APPROACH FIX The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment. It is designated on Government charts by the Maltese Cross symbol for nonprecision approaches and the lightning bolt symbol, designating the PFAF, for precision approaches; or when ATC directs a lower-than-published glideslope/path or vertical path intercept altitude, it is the resultant actual point of the glideslope/path or vertical path intercept.

FINAL APPROACH POINT The point, applicable only to a nonprecision approach with no depicted FAF (such as an on airport VOR), where the aircraft is established inbound on the final approach course from the procedure turn and where the final approach descent may be commenced. The FAP serves as the FAF and identifies the beginning of the final approach segment.

DECISION ALTITUDE A specified altitude in the precision approach, charted in feet MSL, at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.

DECISION HEIGHT A specified altitude in the precision approach, charted in height above threshold elevation, at which a decision must be made either to continue the approach or to execute a missed approach.

MINIMUM DESCENT ALTITUDE The lowest altitude (in feet MSL) to which descent is authorized on final approach, or during circle-to-land maneuvering in execution of a nonprecision approach.

THRESHOLD CROSSING HEIGHT The theoretical height above the runway threshold at which the aircraft’s glideslope antenna would be if the aircraft maintains the trajectory established by the mean ILS glideslope or the altitude at which the calculated glidepath of an RNAV or GPS approaches.

HEIGHT ABOVE TOUCHDOWN The height of the Decision Height or Minimum Descent Altitude above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway). HAT is published on instrument approach charts in conjunction with all straight-in minimums.

HEIGHT ABOVE AIRPORT The height of the Minimum Descent Altitude above the published airport elevation. This is published in conjunction with circling minimums.

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.

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.

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.

DESCEND VIA– An abbreviated ATC clearance that requires compliance with a published procedure lateral path and associated speed restrictions and provides a pilot-discretion descent to comply with published altitude restrictions.

Localizer Performance with Vertical Guidance
LPV approaches take advantage of the refined accuracy of WAAS lateral and vertical guidance to provide an approach very similar to a Category I ILS. Like an ILS, an LPV has vertical guidance and is flown to a Decision Altitude (DA). The design of an LPV approach incorporates angular guidance with increasing sensitivity as an aircraft gets closer to the runway (or point in space (PinS) type approaches for helicopters). Sensitivities are nearly identical to those of the ILS at similar distances. This is intentional to aid pilots in transferring their ILS flying skills to LPV approaches.

Lateral Navigation/Vertical Navigation
LNAV/VNAV approaches provide both horizontal and approved vertical approach guidance. Vertical Navigation (VNAV) utilizes an internally generated glideslope based on WAAS or baro-VNAV systems. Minimums are published as a DA. If baro-VNAV is used instead of WAAS, the pilot may have approach restrictions as a result of temperature limitations and must check predictive RAIM (Receiver Autonomous Integrity Monitoring). [Airplanes that are commonly approved in these types of operations include Boeing 737NG, 767, and 777, as well as the Airbus A300 series.]

Localizer Performance without Vertical Guidance (LP) and Lateral Navigation (LNAV)
LPs are non-precision approaches with WAAS lateral guidance. They are added in locations where terrain or obstructions do not allow publication of vertically guided LPV procedures. Lateral sensitivity increases as an aircraft gets closer to the runway. LP is not a fail-down mode for an LPV. LP and LPV are independent. LP minimums will not be published with lines of minima that contain approved vertical guidance (LNAV/VNAV or LPV).

LNAV approaches are non-precision approaches that provide lateral guidance. The pilot must check RAIM (Receiver Autonomous Integrity Monitoring) prior to the approach when not using WAAS equipment.

Depending on the manufacturer, a few WAAS-enabled GPS units provide advisory vertical guidance in association with LP or LNAV approaches. Typically, the manufacturer will use the notation of LNAV+V. The system includes an artificially created advisory glide path from the final approach fix to the touchdown point on the runway. This may aid the pilot in flying constant descent to the MDA.

All definitions above from the Pilot Controller Glossary except MDA, MORA, COP, DA, DH, and TDZE are from the Instrument Flying Handbook. MTA from the AIM. LPV, lNAV/VNAV, LP/LNAV, LNAV+V from RNAV (GPS) Approaches

Things to Remember IFR Checkride—Weather

June 14th, 2017

§91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include—

(a) For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;

Ceiling is Broken or Overcast
Ceiling means 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.

1/8-2/8 Few
3/8-4/8 Scattered
5/8-7/8 Broken
8/8 Overcast

Pre-Flight Weather & Notices
Always know where the nearest VFR is along the route of flight.

Departure and Destination Airports

Surface Analysis
Ceilings along route
Freezing Levels relative to MEAs and MOCAs
Winds and Temps Aloft
Airmets and Sigmets

Highs and Lows
Low is rising column of counterclockwise air. Sucks in moisture and dust.
High is clockwise movement of air. Air goes downward pushing bad weather away.

Trough is an elongated low.
Ridge is an elongated high.

DUATS Surface Analysis

Surface Analysis

Surface Analysis Legend

Shows cells, Cell movement, Precip Intensity, Cloud/Cell Tops



Prog Charts
Ceiling, turbulence, freezing levels

Prog Charts

Prog Charts

Inflight Flight Weather
If you call for weather on 122.2, make sure you let them know where you are. If you use an RCO make sure you identify it.

These are the sites that I have been using to check local weather and flight restrictions.

WAAS Outages

May 29th, 2017

This airport if the first one that I’ve run across that has this symbol. It it located in the Florida Keys, which probably explains why it may be outside the reach of WAAS.

NOTE: The W symbol indicates outages of the WAAS vertical guidance may occur daily due to initial system limitations. WAAS NOTAMS for vertical outages are not provided for this approach. Use LNAV minima for flight planning at these locations, whether as a destination or alternate. For flight operations at these locations, when the WAAS avionics indicate that LNAV/VNAV or LPV service is available, then vertical guidance may be used to complete the approach using the displayed level of service. Should an outage occur during the procedure, reversion to LNAV minima may be required.
As the WAAS coverage is expanded, the W will be removed.

WAAS Outage May Occur.png

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

7. When the approach chart is annotated with the symbol, W site−specific WAAS MAY NOT BE AVBL NOTAMs or Air Traffic advisories are not provided for outages in WAAS LNAV/VNAV and LPV vertical service. Vertical outages may occur daily at these locations due to being close to the edge of WAAS system coverage. Use LNAV or circling minima for flight planning at these locations, whether as a destination or alternate. For flight operations at these locations, when the WAAS avionics indicate that LNAV/VNAV or LPV service is available, then the vertical guidance may be used to complete the approach using the displayed level of service. Should an outage occur during the procedure, reversion to LNAV minima may be required.

Diverse Departure Assessment

May 28th, 2017

When you see this symbol AlternateTakeoffMinimumson the approach plate, it means that either there are non-standard takeoff minimums or that there is a published departure procedure. So one way to find airports with a diverse departure is to look for ones without that symbol. It is a necessary, but not sufficient condition.

I downloaded the TPP documents for Florida and California and started looking for airports without the symbol. The only ones I found were a couple of military fields in FLorida. Kansas and Nebraska are pretty flat, so I looked at the TPP NC2 plates and found KAIA.

There are no notes for this approach and none of the approaches at this airport have Alternate Takeoff Minimums symbol. If you look at the approach plate there is only one obstacle several miles away and about 1800′ above the airport. It would be hard to hit it with a standard IFR climb.

Dodge City, Harper Muni, Neodesha Muni, Platsmouth Muni, Pratt Regional, Smith Center Regional, Cessna Aircraft Field (but not the Beech Aircraft field just a few miles away) all have diverse departure assessment departures. So there aren’t a lot of them, but they aren’t unicorns.


May 25th, 2017

I previously wrote about replacing the battery in an ELT. This post talks about testing the ELT at each annual or after battery replacement.

§91.207 Emergency locator transmitters.
(d) Each emergency locator transmitter required by paragraph (a) of this section must be inspected within 12 calendar months after the last inspection for—
  (1) Proper installation;
  (2) Battery corrosion;
  (3) Operation of the controls and crash sensor; and
  (4) The presence of a sufficient signal radiated from its antenna.

I’ve done around 30 annuals and we never tested the crash sensors. It turns out that there is a procedure for it in AC 43.13-1B

A TSO-C91 ELT can be activated by using a quick rap with the palm. A TSO-C91a ELT can be activated by using a rapid forward (throwing) motion coupled by a rapid reversing action. Verify that the ELT can be activated using a watt meter, the airplane’s VHF radio communications receiver tuned to 121.5 MHz, or other means (see NOTE 1). Insure that the “G” switch has been reset if applicable.

If I am reading the ACK manual correctly, the listening for the sweeps when the unit is switched to ON is all you need to do. From the ACK website,

Model E-01 Emergency Locator Transmitter The model E-01 ELT must be inspected yearly to insure continued airworthiness. The procedures as described in section 7 (Periodic Maintenance) of the installation and operation manual part number E-01-M (all revision dates) should be followed. These tests also fulfill the requirements of FAR 91.207.

There is no mention of performing a test of the crash sensor.

Things to Remember IFR Checkride

May 24th, 2017

Common Mistakes
Make sure you ask the examiner to clear the area before maneuvers.
Use checklists for all phases of flight—if using a mnemonic, tell the examiner what you are doing.
Use rudder for small corrections on final.

Setup for stabilized approach 4 miles before FAF.
10° Flaps, Landing Gear down, Prop in, Mixture in, Boost Pump on
Missed reviewed and set up.

Going Missed
Cram – Power In
Climb – Nose on Horizon
Clean – Gear first, then flaps
Cool – Mixture and Cowl Flaps
Communicate – Let the tower know you are going missed.

IFR Privileges
For Part 91 pilots an instrument flight plan is required to enter IMC in controlled airspace and to enter Class A airspace.

Fly in Instrument Meteorological Conditions (IMC) including Class G.
File and fly under Instrument Flight Rules (IFR).
Fly in Class A airspace.
Fly Special VFR at Night (if airplane is also IFR)
If a commercial pilot, carry passengers for hire at night or in excess of 50 NM.

Pilot Requirements to fly IFR
Six approaches, holding patterns, and intercepting courses in previous six months.
Current and appropriate medical for the type of flight.
Current flight review.

If flying with passengers: Within the previous 90 days
Three takeoffs and landings
If flying between 1 hour after sunset and 1 hour before sunrise:
Three takeoffs and landing to a full stop in that time.

IFR Equipment Required
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 capable of displaying seconds.

(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).

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

Directional gyro
Check, in straight and level flight, about every 15 minutes, after a holding pattern, and before starting an approach.

At Each Waypoint
Morse, Source, Course
If ILS or Localizer, listen for Morse Code, Verify Source on GPS, Set Course on Heading Indicator and OBS

Altitude for Leg
Attitude on Heading Indicator
Active Leg Is Shown On GPS
ATC Communication

Next Leg, Waypoint, or Missed Approach. Load frequencies for Nav and Coms.

At 30 NM each dot is appoximately 1 NM displacement.
So 1 NM is ~200′.

Airworthy Aircraft
Current Registration
100 Hour AD items
Transponder – 24 months
Altimeter- 24 months
Pitot/Static- 24 months
ELT – 12 Months Inspection, Replaced at 24 months or 50%

GPS Database Current (New version every 28 days.)
VOR check within 30 days

Inoperative Equipment
As long as it is not required you may:
Use Minimum Equipment List (MEL) if applicable,
Inop Sticker and Deactiveate,
Inop Sticker and Remove (W&B may be required).

Ferry Permit if Required Equipment is inoperative

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

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

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.

ATC Reports
Safety of flight—Icing, Turbulence, Bird Strike, Engine Trouble, etc.
Time and altitude reaching a holding fix
Airspeed (true) change of 10 kts or 5% whichever is greater.
Loss of nav equipment and degree to which ability to operate in system is affected
Leaving hold
Missed approach
Unable to climb or descend at 500 fpm
Unforecast weather
Vacating assigned altitude
Altitude change VFR-On-Top

§91.183 IFR communications.
(a) The time and altitude of passing each designated reporting point…
(b) Any unforecast weather conditions encountered; and
(c) Any other information relating to the safety of flight.

§91.187 Operation under IFR in controlled airspace: Malfunction reports.
any malfunctions of navigational, approach, or communication equipment occurring in flight.

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 Reports
ETA Next fix
Name of succeeding fix

Operating Below DA/DH or MDA
Flight Visibility > Minimums
Land Using Normal Manuevers (in the Touchdown Zone Part 121 and 135)
Have the Runway Environment in sight

14 CFR §91.175 Takeoff and landing under IFR.

(c) Operation below DA/DH or MDA.
Except as provided in paragraph (l) of this section, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless—

(1) The aircraft is continuously 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 part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach being used; and

(3) Except for a Category II or Category III approach where any necessary visual reference requirements are specified by the Administrator, at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot:

(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.

Threshold—The beginning of that portion of the runway usable for landing.
Displaced Threshold—A threshold that is located at a point on the runway other than the designated beginning of the runway.
Touchdown zone—The first three thousand feet of the runway, beginning at the threshold. Note: This is why there are three sets of stripes along the runway. The first set and the aiming point are in the first 1,000′. Two sets with two stipes are in the second 1,000′. Two sets with 1 stripe are in the final 1,000′ of the TDZ.

Filing IFR
No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to—
Complete the flight to the first airport of intended landing;
Fly from that airport to the alternate airport; and
Fly after that for 45 minutes at normal cruising speed.

Non-WAAS equipped aircraft may file based on a GPS−based IAP at either the destination or the alternate airport, but not at both locations. 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. (Not LPV.)

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.

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. At the estimated time of arrival.

Standard alternate minimums for precision approaches (ILS, PAR, or GLS) are 600-2. At the estimated time of arrival.

If no instrument approach procedure at the destination the ceiling and visibility minima are those allowing descent from the MEA, approach, and landing under basic VFR. An alternate is required.

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.

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. Part 91 has no takeoff minimums—a 0/0 departure is legal.

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.

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.
Obstacle Departure Procedures (ODP) are only used for obstruction clearance and do not include ATC related climb requirements.
A Standard Instrument Departure (SID) is an ATC-requested and developed departure route. Must have at least the textual description of the procedure.
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.
A radar departure is another option.

Using GPS
Databases must be updated for IFR operations and should be updated for all other operations.
Always load the full approach — not vectors-to-final — even if that is what they give you.

Ground−based navigation equipment is not required to be installed and operating for en route IFR operations when using GPS/WAAS navigation systems. All operators should ensure that an alternate means of navigation is available in the unlikely event the GPS/WAAS navigation system becomes inoperative.

Pilots are not authorized to fly a published RNAV or RNP departure procedure unless it is retrievable by the procedure name from the navigation database and conforms to the charted procedure.

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.

As soon as you turn onto a localizer or ILS, you need to display course guidance from the Nav radio… For a VOR approach, the answer is different you can fly all the way to the FAF before you need to switch the CDI or HSI to the Nav radio.

IFR Approach and Departure
GPS IFR approach/departure operations can be conducted when approved avionics systems are installed and the following requirements are met:
  (1) The aircraft is [GPS/WAAS certified]… and
  (2) The approach/departure must be retrievable from the current airborne navigation database in the navigation computer. The system must be able to retrieve the procedure by name from the aircraft navigation database. Manual entry of waypoints using latitude/longitude or place/bearing is not permitted for approach procedure.

GPS overlay approaches are designated non−precision instrument approach procedures that pilots are authorized to fly using GPS avionics. Overlay procedures are identified by the “name of the procedure” and “or GPS” (e.g., VOR/DME or GPS RWY 15) in the title.

Minimums at Controlled Airports
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 ground visibility at that airport is at least 3 statute miles.

The same minimums apply to visual approaches. Contact approaches only require 1 SM visibility and COC.

Lost Comms
Route – AVEnue F
Assigned, Vectored, Expected, Filed

Altitude – MEA
Minimum IFR Altitude
Highest for route.

Squawk 7600

Recommended altitude for using oxygen at night is 5,000′ and 10,000′ during the day.

12.500 for more than 30 minutes
14,000 for crew
15,000 made available for passengers

Tower Enroute Control route can be requested from Ground.
On initial call say you have an IFR request.
Ask for a TEC to your destination. Know the route when you request because they will give you a route, e.g. SBAN47 or CSTN24

With GPS you can file or request MOCA altitudes if the MEA requires oxygen, icing is possible at the MEA, or you want a better ride below the cloud deck.

MRAs for identifying intersections aren’t necessary if you have GPS.

Required Documents in the Airplane

May 17th, 2017

We are all taught the ARROW acronym—Airworthiness Certificate, Registration, Radio License, Operating Limitations, Weight and Balance. I previously wrote about this topic and thought that it deserved a revisit.

There are three occasions when you may be asked for these documents. When being ramp checked, when the aircraft goes in for an annual inspection, or when the aircraft is involved in an accident or incident.

AIRCRAFT DOCUMENTS. Following are considerations when examining aircraft documents, including registration and airworthiness certificates and approved flight manuals. Discrepancies found concerning the airworthiness or registration certificates shall be brought to the attention of the operator, documented, and given to the airworthiness unit for action.
A. N-Numbers. The N-number on the registration certificate must match the N-number on the airworthi­ness certificate.
B. Registration Certificate. If the registered owner has changed you may see a temporary registration (Pink Slip) which is good for 120 days. If the ownership has changed without a Pink Slip or the N- numbers do not match, the registration is not valid.
C. Radio Station License. An aircraft FCC radio license is required although the FAA does not regulate the requirement. The license may be for that particular N-number or a fleet license. The expiration date of the license is in the upper right hand corner. Any discrep­ancy concerning the radio license should be brought to the attention of the operator only.
D. Flight Manual. An Aircraft Flight Manual is required to be on board the aircraft (FAR § 91.9 {91.31}) along with the appropriate markings and placards.
E. Weight and Balance Information. Weight and balance documents, including a list of equipment, must be on board the aircraft. Some multiengine operators have Minimum Equipment Lists (MEL’s) with a letter of authorization issued by a district office. These constitute a supplemental type certificate for the aircraft and must be on board. The inspector should compare inop­erative equipment to the MEL to assure compliance. (Refer to Related Task #58, Approve a Minimum Equipment List.)
F. Airworthiness Certificate. The certificate most often seen by an inspector is a standard airworthiness certificate, which is issued for normal, utility, acrobatic, and transport category aircraft. A restricted, limited, or experimental certificate must be accompanied by a list of limitations and conditions (FAR § 21.183 -191) necessary for safe operation. A Special Flight Permit (Ferry Permit) is issued to aircraft that may not be airworthy but are capable of safe flight under certain conditions which are listed and issued with the permit (FAR §§ 21.197 , 91.203 {91.27}, and 91.213 {91.30}). Review the list of limitations and conditions to assure a valid airworthiness certificate. The N-number on the certificate must match the N-number on the fuselage to be valid.

Airworthiness Certificate and Registration Certificate
The standard airworthiness certificate is issued when the airplane is manufactured or when the N number changes. In addition to the standard Airworthiness Certificate, there are Experimental, Restricted, or Special Flight Certificates that may apply to your aircraft.

Registrations must be renewed every three years. The FAA has a page that explains the process. You can also check the status of an aircrafts registration and who it is registered to on the FAA website.

§91.203 Civil aircraft: Certifications required.
(a) Except as provided in §91.715, no person may operate a civil aircraft unless it has within it the following:

(1) An appropriate and current airworthiness certificate. Each U.S. airworthiness certificate used to comply with this subparagraph (except a special flight permit, a copy of the applicable operations specifications issued under §21.197(c) of this chapter [Special flight permits], …
(2) An effective U.S. registration certificate issued to its owner or, for operation within the United States, the second copy of the Aircraft registration Application as provided for in §47.31(c), a Certificate of Aircraft registration as provided in part 48, or a registration certification issued under the laws of a foreign country.

Radio Station License
A radio station and operators license is required if you make international flights or communicate with foreign stations. As far as I can tell, this requirement is not enforced for flights to Canada, Mexico, and the Caribbean. I got my restricted operators permit in 1980 when they were still required for domestic operations but have not flown internationally.

…you do not need a license to operate a two-way VHF radio, radar, or emergency locator transmitter (ELT) aboard aircraft operating domestically. All other aircraft radio stations must be licensed by the FCC either individually or by fleet. Aircraft operating domestically do not land in a foreign country or communicate via radio with foreign ground stations.FAA

You must obtain an FCC Aircraft Radio Station License if you make international flights or communicate with foreign stations. If you are not required to obtain a license – you do not need to file this form [Form 605] with the FCC. The license has a term of 10 years.

At least one person on each aircraft flying or communicating internationally must have a Restricted Radiotelephone Operator Permit. This requirement is in addition to the requirement to have an aircraft radio station license for the aircraft. No Restricted Radiotelephone Operator Permit is required to operate VHF radio equipment on board an aircraft when that aircraft is flown domestically. You may obtain a Restricted Permit using FCC Form 605. No test is required to obtain this permit. The permit when issued will be valid for your lifetime. The fee for a Restricted Permit is in addition to any fee paid for an aircraft license.FAA

§87.18 Station license required.
(a) Except as noted in paragraph (b) of this section, stations in the aviation service must be licensed by the FCC either individually or by fleet.

(b) An aircraft station is licensed by rule and does not need an individual license issued by the FCC if the aircraft station is not required by statute, treaty, or agreement to which the United States is signatory to carry a radio, and the aircraft station does not make international flights or communications. Even though an individual license is not required, an aircraft station licensed by rule must be operated in accordance with all applicable operating requirements, procedures, and technical specifications found in this part.

§87.87 Classification of operator licenses and endorsements.
(b) The following licenses are issued by the Commission. International classification, if different from the license name, is given in parentheses. The licenses and their alphanumeric designator are listed in descending order.
(7) RP Restricted Radiotelephone Operator Permit (radiotelephone operator’s restricted certificate)

§87.89 Minimum operator requirements.
(a) A station operator must hold a commercial radio operator license or permit…

Acceptable Radios
As of January 1, 1997, each VHF aircraft radio used on board a U.S. aircraft must be type accepted by the FCC as meeting a 30 parts-per-million (ppm) frequency tolerance (47 C.F.R. § 87.133). The vast majority of aircraft radios that have been type accepted under the 30 ppm frequency tolerance utilize 25 kHz spacing and have 720 or 760 channels. Each aircraft radio has a label with an FCC ID number on the unit. See this post for a short history of radio frequencies.

Operating Limitations
This part of the acronym seems to generate the most confusion. Per §21.5 aircraft delivered after March 1, 1979 must have an FAA approved flight manual (AFM). Aircraft prior to that date were delivered with an Owner’s Handbook, Pilot’s Operating Handbook, Owner’s Manual, Information Manual or similarly named booklet. These did not have a standard format and the information contained in them varied wildly. They are not required to be in the airplane, however since they give information like landing and takeoff distances—which are required to be calculated for each flight—it would make sense to have them readily available. Many aircraft were sold with an Airplane Flight Manual that listed the operating limitations, required placards, instrument markings, installed equipment, and the weight and balance information when the aircraft left the factory. There is no regulation requiring that they be in the plane.

The placards listed in the type certificate are required, so if you get your panel redone—as we did—then you’ll need to make sure you have all of the required placards. The placards list operating limitations like maximum baggage weight, spins prohibited, fuel tank switching procedures, etc. They also mark things like the throttle, mixture, fuel selector, etc.

There are a few ADs that require placards and if you aircraft is subject to the AD, then you must have the placard displayed.

If you have equipment like a GPS or autopilot installed, the STC may require that the operating manual for the equipment be carried in the aircraft. These are generally referred to as flight manual supplements.

If an FAA approved flight manual is required, it is specific to that airplane and is required to be in the aircraft along with any required flight manual supplements.

§91.9 Civil aircraft flight manual, marking, and placard requirements.
(a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.

(b) No person may operate a U.S.-registered civil aircraft—

(1) For which an Airplane or Rotorcraft Flight Manual is required by §21.5 of this chapter unless there is available in the aircraft a current, approved Airplane or Rotorcraft Flight Manual or the manual provided for in §121.141(b); and

(2) For which an Airplane or Rotorcraft Flight Manual is not required by §21.5 of this chapter, unless there is available in the aircraft a current approved Airplane or Rotorcraft Flight Manual, approved manual material, markings, and placards, or any combination thereof.

(c) No person may operate a U.S.-registered civil aircraft unless that aircraft is identified in accordance with part 45 of this chapter.

The reference it part 45 is regarding the placement and size of the N number.

§21.5 Airplane or Rotorcraft Flight Manual.
(a) With each airplane or rotorcraft not type certificated with an Airplane or Rotorcraft Flight Manual and having no flight time before March 1, 1979, the holder of a type certificate (including amended or supplemental type certificates) or the licensee of a type certificate must make available to the owner at the time of delivery of the aircraft a current approved Airplane or Rotorcraft Flight Manual.

(b) The Airplane or Rotorcraft Flight Manual required by paragraph (a) of this section must contain the following information:

(1) The operating limitations and information required to be furnished in an Airplane or Rotorcraft Flight Manual or in manual material, markings, and placards, by the applicable regulations under which the airplane or rotorcraft was type certificated.

(2) The maximum ambient atmospheric temperature for which engine cooling was demonstrated must be stated in the performance information section of the Flight Manual, if the applicable regulations under which the aircraft was type certificated do not require ambient temperature on engine cooling operating limitations in the Flight Manual.

Weight and Balance
Neither of my airplanes is required to have a §21.5 “approved Airplane or Rotorcraft Flight Manual” ergo, they are not required to have a W&B in the plane. You could also argue that “§23.1589 (a) The weight and location of each item of equipment that can be easily removed, relocated, or replaced and that is installed when the airplane was weighed under the requirement of §23.25.” does not require that an updated W&B be included in the AFM only that one must be provided by the manufacturer.

I am not aware of any FAR that requires that a current weight and balance be in the airplane if it is not required to have an approved AFM. However, since the list of things that an FAA inspector is looking for on a ramp check includes a W&B, most people carry it.

§23.1589 Loading information.
The following loading information must be furnished:

(a) The weight and location of each item of equipment that can be easily removed, relocated, or replaced and that is installed when the airplane was weighed under the requirement of §23.25.

(b) Appropriate loading instructions for each possible loading condition between the maximum and minimum weights established under §23.25, to facilitate the center of gravity remaining within the limits established under §23.23.

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.


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.

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.

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


Alternate static source:
Altimeter higher, Airspeed greater than actual

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.
1″ decrease for each 1000′ decrease 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.

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.

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.

At 30 NM each dot is appoximately 1 NM displacement.
So 1 NM is ~200′.
Minutes to station = Time (seconds)/Bearing Change (degrees)

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

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.

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.

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.

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.


     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.

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′.

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.

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.

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

Stagnant hypoxia or ischemia results when the oxygen-rich blood in the lungs is not moving, for one reason or another, to the tissues.
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

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′. The dewpoint decreased .5°C per 1000′.
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.

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

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.

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).

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.

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
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.

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)
“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′.
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.

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.

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.

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.

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

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 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

Miscellaneous Things I Can’t Remember

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.

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.

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


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


Radar Loop
Aviation Weather Center


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

TFRs, NOTAMs, and Special Use Airspace


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.

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).

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.

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 you 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.

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 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 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 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 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 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 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).

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.

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.

The transition boundary between the troposphere and the 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.

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.

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

The transition boundary that separates the exosphere from the thermosphere.

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

29.92 Inches of Mercury

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 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.


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.

Aviation Training Device

March 25th, 2017

I use a flight simulator (X-Plane) to practice instrument approaches and have used FlyThisSim at the local flight school for training. However, these are not flight simulators in the eyes of the FAA so you need to understand the terminology in order to log the time on them.

A good place to start is AC 61-136A Aviation Training Devices. This lays out the difference between Basic and Advanced Aviation Training Devices. The FlyThisSim device meets the qualifications of a BATD. You can find their Letter of Authorization (LOA) on their website. Even though I am running the same software on my computer, it doesn’t meet the requirements for an Aviation Training Device so none of the time is loggable. The Redbird systems more sophisticated and are Advanced Aviation Training Devices.

You can use the time in an Aviation Training Device to fulfill part of the experience requirements for various pilot ratings. The part that was confusing to me was the ability to maintain currency for IFR flight. Here’s where the difference in semantics becomes important. A BATD or AATD is not a flight simulator or flight training device. Therefore you can use it to maintain IFR currency if you comply with §61.57 (c) Instrument experience. but only the third section.

(3) Use of an aviation training device for maintaining instrument experience. Within the 2 calendar months preceding the month of the flight, that person performed and logged at least the following tasks, iterations, and time in an aviation training device and has performed the following—

(i) Three hours of instrument experience.
(ii) Holding procedures and tasks.
(iii) Six instrument approaches.
(iv) Two unusual attitude recoveries while in a descending, Vne airspeed condition and two unusual attitude recoveries while in an ascending, stall speed condition.
(v) Interception and tracking courses through the use of navigational electronic systems.

§61.51 Pilot logbooks. details the requirements for logging time and requires an instructor to be present and sign the logbook if an Aviation Training Device is used to satisfy the recency requirement.

(g) Logging instrument time. (1) A person may log instrument time only for that flight time when the person operates the aircraft solely by reference to instruments under actual or simulated instrument flight conditions.

(4) A person can use time in a flight simulator, flight training device, or aviation training device for acquiring instrument aeronautical experience for a pilot certificate, rating, or instrument recency experience, provided an authorized instructor is present to observe that time and signs the person’s logbook or training record to verify the time and the content of the training session.

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 times 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.

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 eery 2% decrease in aircraft weight from max gross, decrease maneuvering speed by 10%.


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.


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. 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 ROC 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 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.

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 –

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.]

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 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.

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 230 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.

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)

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 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.

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

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.

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.

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.

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.

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.

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.

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.

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.

• 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.

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

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.

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.

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.

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.

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