Aeronautical Terms beginning with S
SA
Selective Availability.
SAA
Special Activity Airspace
Safety Alert
A safety alert issued by ATC to aircraft under their control if ATC is aware the aircraft is at an altitude which, in the controller’s judgment, places the aircraft in unsafe proximity to terrain, obstructions, or other aircraft. The controller may discontinue the issuance of further alerts if the pilot advises he/she is taking action to correct the situation or has the other aircraft in sight. Note: The issuance of a safety alert is contingent upon the capability of the controller to have an awareness of an unsafe condition. The course of action provided will be predicated on other traffic under ATC control. Once the alert is issued, it is solely the pilot’s prerogative to determine what course of action, if any, he/she will take.
SAM
System Area Monitor
Same Direction Aircraft
Aircraft are operating in the same direction when: a. They are following the same track in the same direction; or b. Their tracks are parallel and the aircraft are flying in the same direction; or c. Their tracks intersect at an angle of less than 45 degrees.
SAMS
Special Use Airspace Management System
SAR
Search and Rescue
SATCOM
Satellite Communications.
Satellite ephemeris data
Data broadcast by the GPS satellite containing very accurate orbital data for that satellite, atmospheric propagation data, and satellite clock error data.
SATNAV
Satellite Navigation
Say Again
Used to request a repeat of the last transmission. Usually specifies transmission or portion thereof not understood or received; e.g., “Say again all after ABRAM VOR.”
Say Altitude
Used by ATC to ascertain an aircraft’s specific altitude/flight level. When the aircraft is climbing or descending, the pilot should state the indicated altitude rounded to the nearest 100 feet.
Say Heading
Used by ATC to request an aircraft heading. The pilot should state the actual heading of the aircraft.
SBAS
Satellite-based Augmentation System
Sea Lane
A designated portion of water outlined by visual surface markers for and intended to be used by aircraft designed to operate on water.
Sea Level
A reference height used to determine standard atmospheric conditions and altitude measurements.
Search And Rescue
A service which seeks missing aircraft and assists those found to be in need of assistance. It is a cooperative effort using the facilities and services of available Federal, state and local agencies. The U.S. Coast Guard is responsible for coordination of search and rescue for the Maritime Region, and the U.S. Air Force is responsible for search and rescue for the Inland Region. Information pertinent to search and rescue should be passed through any air traffic facility or be transmitted directly to the Rescue Coordination Center by telephone.
Search And Rescue Facility
A facility responsible for maintaining and operating a search and rescue (SAR) service to render aid to persons and property in distress. It is any SAR unit, station, NET, or other operational activity which can be usefully employed during an SAR Mission; e.g., a Civil Air Patrol Wing, or a Coast Guard Station.
SECNOT
Security Notice
Sectional aeronautical charts
Designed for visual navigation of slow- or medium-speed aircraft. Topographic information on these charts features the portrayal of relief, and a judicious selection of visual check points for VFR flight. Aeronautical information includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions and related data.
See And Avoid
When weather conditions permit, pilots operating IFR or VFR are required to observe and maneuver to avoid other aircraft. Right-of-way rules are contained in 14 CFR Part 91.
Segmented Circle
A visual ground based structure to provide traffic pattern information.
Segments Of An Instrument Approach Procedure
An instrument approach procedure may have as many as four separate segments depending on how the approach procedure is structured. Initial Approach, Intermediate Approach, Final Approach, and Missed Approach.
Selective availability (SA)
A satellite technology permitting the Department of Defense (DOD) to create, in the interest of national security, a significant clock and ephemeris error in the satellites, resulting in a navigation error.
Sensitive altimeter
A form of multipointer pneumatic altimeter with an adjustable barometric scale that allows the reference pressure to be set to any desired level.
Service
A generic term that designates functions or assistance available from or rendered by air traffic control. For example, Class C service would denote the ATC services provided within a Class C airspace area.
Service ceiling
The maximum density altitude where the best rate-of-climb airspeed will produce a 100-feet-per-minute climb at maximum weight while in a clean configuration with maximum continuous power.
Severe Icing
The rate of accumulation is such that deicing/anti-icing equipment fails to reduce or control the hazard. Immediate flight diversion is necessary.
SFL
Sequenced Flashing Lights
SFR
Special Flight Rules
Short Takeoff And Landing Aircraft
An aircraft which, at some weight within its approved operating weight, is capable of operating from a runway in compliance with the applicable STOL characteristics, airworthiness, operations, noise, and pollution standards.
Show
Unless the context otherwise requires, to show to the satisfaction of the Administrator.
Sideslip
A slip in which the airplane’s longitudinal axis remains parallel to the original flightpath, but the airplane no longer flies straight ahead. Instead, the horizontal component of wing lift forces the airplane to move sideways toward the low wing.
SIGMET
A weather advisory issued concerning weather significant to the safety of all aircraft. SIGMET advisories cover severe and extreme turbulence, severe icing, and widespread dust or sandstorms that reduce visibility to less than 3 miles.
Simplex
Transmission and reception on the same frequency.
Single-Pilot Resource Management (SRM)
The art/science of managing all the resources (both onboard the aircraft and from outside sources) available to a single pilot (prior and during flight) to ensure that the successful outcome of the flight is never in doubt.
Situational awareness
Pilot knowledge of where the aircraft is in regard to location, air traffic control, weather, regulations, aircraft status, and other factors that may affect flight.
Skid
A condition where the tail of the airplane follows a path outside the path of the nose during a turn.
Skidding turn
An uncoordinated turn in which the rate of turn is too great for the angle of bank, pulling the aircraft to the outside of the turn.
Slant range
The horizontal distance from the aircraft antenna to the ground station, due to line-of-sight transmission of the DME signal.
Slaved compass
A system whereby the heading gyro is “slaved to,” or continuously corrected to bring its direction readings into agreement with a remotely located magnetic direction sensing device (usually a flux valve or flux gate compass).
Slip
An intentional maneuver to decrease airspeed or increase rate of descent, and to compensate for a crosswind on landing. A slip can also be unintentional when the pilot fails to maintain the aircraft in coordinated flight.
Slipping turn
An uncoordinated turn in which the aircraft is banked too much for the rate of turn, so the horizontal lift component is greater than the centrifugal force, pulling the aircraft toward the inside of the turn.
Slow Taxi
To taxi a float plane at low power or low RPM.
SM
Statute Mile
Small
An Aircraft Class Wake Turbulence Separation Minima. Aircraft of 41,000 pounds or less maximum certificated takeoff weight.
Small Aircraft
An aircraft weighing 12,500 pounds or less, maximum certificated takeoff weight. As defined in 14 CFR part 1.
SNR
Signal-to-noise Ratio
SOP
Standard Operating Procedure
Speak Slower
Used in verbal communications as a request to reduce speech rate.
Special Activity Airspace (SAA)
Any airspace with defined dimensions within the National Airspace System wherein limitations may be imposed upon aircraft operations. This airspace may be restricted areas, prohibited areas, military operations areas, air ATC assigned airspace, and any other designated airspace areas. The dimensions of this airspace are programmed into URET and can be designated as either active or inactive by screen entry. Aircraft trajectories are constantly tested against the dimensions of active areas and alerts issued to the applicable sectors when violations are predicted.
Special Emergency
A condition of air piracy or other hostile act by a person(s) aboard an aircraft which threatens the safety of the aircraft or its passengers.
Special flight permit
A flight permit issued to an aircraft that does not meet airworthiness requirements but is capable of safe flight. A special flight permit can be issued to move an aircraft for the purposes of maintenance or repair, buyer delivery, manufacturer flight tests, evacuation from danger, or customer demonstration. Also referred to as a ferry permit.
Special Use Airspace
Airspace of defined dimensions identified by an area on the surface of the earth wherein activities must be confined because of their nature and/or wherein limitations may be imposed upon aircraft operations that are not a part of those activities. Types of special use airspace are: Alert Area, Controlled Firing Area, Military Operations Area (MOA), Prohibited Area, Restricted Area, and Warning Area.
Special VFR Conditions
Meteorological conditions that are less than those required for basic VFR flight in Class B, C, D, or E surface areas and in which some aircraft are permitted flight under visual flight rules.
Special VFR Operations
Aircraft operating in accordance with clearances within Class B, C, D, and E surface areas in weather conditions less than the basic VFR weather minima. Such operations must be requested by the pilot and approved by ATC.
Speed
The distance traveled in a given time.
Spin
An aggravated stall that results in what is termed an “autorotation” wherein the airplane follows a downward corkscrew path. As the airplane rotates around the vertical axis, the rising wing is less stalled than the descending wing creating a rolling, yawing, and pitching motion.
Spiral instability
A condition that exists when the static directional stability of the airplane is very strong as compared to the effect of its dihedral in maintaining lateral equilibrium.
Spiraling slipstream
The slipstream of a propeller-driven airplane rotates around the airplane. This slipstream strikes the left side of the vertical fin, causing the aircraft to yaw slightly. Rudder offset is sometimes used by aircraft designers to counteract this tendency.
SPS
Standard Positioning Service
SPT
Strategic Planning Team. The Strategic Planning Team acts as a focal point for the development of collaborative Strategic Plans of Operation. Their goal is to provide advanced planning information for system users and air traffic facilities in order to maximize the utilization of the NAS in an organized and equitable manner.
Squawk (Mode, Code, Function)
Activate specific modes/codes/functions on the aircraft transponder; e.g., “Squawk three/alpha, two one zero five, low.”
SRM
Single-pilot Resource Management.
SSR
Secondary Surveillance Radar.
SSV
Standard Service Volume.
Stabilator
A single-piece horizontal tail surface on an airplane that pivots around a central hinge point. A stabilator serves the purposes of both the horizontal stabilizer and the elevators.
Stability
The inherent quality of an airplane to correct for conditions that may disturb its equilibrium, and to return or to continue on the original flightpath. It is primarily an airplane design characteristic.
Stabilized Approach
A landing approach in which the pilot establishes and maintains a constant angle glidepath towards a predetermined point on the landing runway. It is based on the pilot’s judgment of certain visual cues, and depends on the maintenance of a constant final descent airspeed and configuration.
Stall
A rapid decrease in lift caused by the separation of airflow from the wing’s surface brought on by exceeding the critical angle of attack. A stall can occur at any pitch attitude or airspeed.
Stand By
Means the controller or pilot must pause for a few seconds, usually to attend to other duties of a higher priority. Also means to wait as in “stand by for clearance.” The caller should reestablish contact if a delay is lengthy. “Stand by” is not an approval or denial.
Standard Atmosphere
At sea level, the standard atmosphere consists of a barometric pressure of 29.92 inches of mercury (in. Hg.) or 1013.2 millibars, and a temperature of 15°C (59°F). Pressure and temperature normally decrease as altitude increases. The standard lapse rate in the lower atmosphere for each 1,000 feet of altitude is approximately 1 in. Hg. and 2°C (3.5°F). For example, the standard pressure and temperature at 3,000 feet mean sea level (MSL) is 26.92 in. Hg. 29.92" Hg – 3" Hg) and 9°C (15°C - 6°C).
Standard Day
See Standard Atmosphere.
Standard Instrument Approach Procedure (SIAP)
Instrument Approach Procedure.
Standard rate turn
A turn in which an aircraft changes its direction at a rate of 3° per second (360° in 2 minutes) for low- or medium-speed aircraft. For high-speed aircraft, the standard rate turn is 1 1⁄2° per second (360° in 4 minutes).
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.
Standard Terminal Arrival (STAR) Charts
Designed to expedite air traffic control arrival procedures and to facilitate transition between en route and instrument approach operations. Each STAR procedure is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location. i. Airport Taxi Charts Designed to expedite the efficient and safe flow of ground traffic at an airport. These charts are identified by the official airport name; e.g., Ronald Reagan Washington National Airport.
Standard-Rate Turn
A turn at the rate of 3º per second which enables the airplane to complete a 360º turn in 2 minutes.
Static longitudinal stability
The aerodynamic pitching moments required to return the aircraft to the equilibrium angle of attack.
Static pressure
Pressure of air that is still or not moving, measured perpendicular to the surface of the aircraft.
Static stability
The initial tendency an aircraft displays when disturbed from a state of equilibrium.
Station
A location in the airplane that is identified by a number designating its distance in inches from the datum. The datum is, therefore, identified as station zero. An item located at station +50 would have an arm of 50 inches.
STC
Supplemental Type Certificate
Steep turns
In instrument flight, any turn greater than standard rate; in visual flight, anything greater than a 45° bank.
STMP
Special Traffic Management Program. Reservation program implemented to regulate arrivals and/or departures at airports that are in areas hosting special events such as the Masters Golf Tournament and Indianapolis 500.
STOL Aircraft
Short Takeoff And Landing Aircraft.
Stop Altitude Squawk
Used by ATC to inform an aircraft to turn-off the automatic altitude reporting feature of its transponder. It is issued when the verbally reported altitude varies 300 feet or more from the automatic altitude report.
Stop And Go
A procedure wherein an aircraft will land, make a complete stop on the runway, and then commence a takeoff from that point.
Stop Squawk (Mode Or Code)
Used by ATC to tell the pilot to turn specified functions of the aircraft transponder off.
Stopway
An area beyond the takeoff runway no less wide than the runway and centered upon the extended centerline of the runway, able to support the airplane during an aborted takeoff, without causing structural damage to the airplane, and designated by the airport authorities for use in decelerating the airplane during an aborted takeoff.
Straight-In Approach VFR
Entry into the traffic pattern by interception of the extended runway centerline (final approach course) without executing any other portion of the traffic pattern.
SUA
Special Use Airspace
Sunset And Sunrise
The mean solar times of sunset and sunrise as published in the Nautical Almanac, converted to local standard time for the locality concerned. Within Alaska, the end of evening civil twilight and the beginning of morning civil twilight, as defined for each locality.
Surface Area
The airspace contained by the lateral boundary of the Class B, C, D, or E airspace designated for an airport that begins at the surface and extends upward.
SVFR
Special Visual Flight Rules
SWAP
Severe Weather Avoidance Plan. An approved plan to minimize the effect of severe weather on traffic flows in impacted terminal and/or ARTCC areas. SWAP is normally implemented to provide the least disruption to the ATC system when flight through portions of airspace is difficult or impossible due to severe weather.
Synthetic vision
A computer-generated image of the external scene topography from the perspective of the flight deck that is derived from aircraft attitude, high-precision navigation solution, and database of terrain, obstacles and relevant cultural features.
Synthetic vision system
An electronic means to display a synthetic vision image of the external scene topography to the flight crew.
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