Aviation Dictionary

On this page you will find a searchable and comprehensive alphabetical list of aviation terms. You can help us make it the most comprehensive list in the world. If we have missed anything, click on the ‘send us your word’ button to send us your word, acronym or definition and we will consider adding it to our dictionary.

Aviation Dictionary: S

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SA Sand
SALR Saturated adiabatic lapse rate
SAR Search and rescue
SARTIME Search and rescue time
SARWATCH Search and rescue watch
SAS Stability augmentation system
SCT Scattered 3-4 Oktas
Separation Point The point on the wing where the boundary layer lifts off the wing surface.
Seven S’s Size, Surface, Shape, Slope, Stock, Sun, Surrounds
SG Snow Grains
SH Showers
Shifting An abrupt change in wind direction.
Shutdown The process of switching off the engines either in flight, or on the ground
SID Standard instrument departure
Sideslip An intentional slip that the pilot induces by using cross controls in order to lose altitude and increase the rate of descent and lose more altitude in a short amount of time.
SIGMET A weather report issued for any significant meteorological conditions that may be present; lightning , severe turbulence , volcanic ash etc
SIGWX Significant weather
Sink A condition where the aircraft feels like it is losing lift and has an increased rate of descent. This can normally be felt during landing where a smooth descent rate is set up and some windshear is experienced, causing a small, sudden drop in altitude.
SEA Single Engine Aeroplane - an aircraft powered by only one engine.
SKC Sky Clear
Skid A condition where the aircraft is yawing away from the intended flight path or is yawing into a turn without the use of roll.
Slat Is a device on the leading edge of the wing that opens up to form a slot
Slip A slip is a condition where the aircraft starts slipping inwards or sideways towards the lower wing. A slip can occur during an uncoordinated turn, or during an intentional side slip to offset a cross wind or to increase drag to increase the aircraft's rate of descent. Both of these slips are caused by cross or uncoordinated flight  controls in roll and yaw.
Slipstream A corkscrew pattern of air behind the propeller which is caused by the acceleration of the air from the propeller.
Slope Refers to the incline of the runway. Normally, most runways have a slight slope of +- 2 degrees. This means that one end of the runway has a slightly higher elevation than the other. Some runways may have a much larger slope and would be a one direction runway because you shouldn’t take-off with a large up slope or land with a large down slope.
Slot Create a pathway for air to flow over a wing to re-energize the airflow over the wing
Slow Flight An attitude of flying where the aircraft is at a high AoA and a low airspeed (1.2Vs). This can be useful for VFR pilots in poor visibility, but more commonly is experienced near any phase of flight that may operate near the stall.
SN Snow
SOP Standard operating procedure
Solo a first solo flight is when the student pilot is deemed ready to fly without an instructor on board.  
Spacing This can be referred to with the distance between aircraft, where in controlled airspace, ATC will ensure sufficient spacing between aircraft, while in uncontrolled airspace, the pilot needs to ensure sufficient spacing between other aircraft. Spacing can also be referred to as the correct distance between the downwind leg and the runway. This spacing is usually conducted at circuit altitude, and where the runway ‘intersects’ part of the airframe in the line of sight of the pilot. The purpose of correct spacing is to ensure that circuits are not flow too wide so that in the event of an engine failure during any part of the circuit, the aircraft is still able to return to the runway to conduct a landing.
Span Also called the wingspan, this is the total distance from wing tip to wing tip
Speci A special aerodrome report issued off the hour.They are prepared when some weather element changes significantly. An improvement of weather conditions must last for at least 10 minutes before a Speci detailing the improvements is issued.
Spin An aggravated stall where one wing produces more lift than the other,which, if not corrected, causes a continuation of roll while the aircraft is stalled. A spin can be either intentional or unintentional and has four phases. If practised correctly, it can be a safe manoeuvre to perform.
Spiral Dive This is a steep descending turn, with a rapidly increasing airspeed because of an excessively nose-down attitude and is generally caused by over-banking.
SQ Squall
Squawk A four digit code which is put into the transponder
SS SAndstorm
SSB Single side band
SSR Secondary surveillance radar
Stall Is a loss of lift that occurs as the wing passes the critical angle. It is NOT an engine stall. There are several factors which can affect a stall or cause a stall to occur at varying airspeeds.
Stagnation Point This is the point where there is no air movement on the wing and is in the area on the leading edge of the wing and can vary slightly based on AoA or relative airflow.
STAR Standard arrival route
Static Pressure The standard pressure on any surface in the atmosphere without any compounding effect, A standard ISA day has a static pressure of 1013.25 hPa and this decreases at 1 hPa / 27 feet of altitude that is gained. Static pressure is supplied to the ASi, VSi and Altimeter.
Static Vents Vents on the surface of the aircraft, placed in a location that will give the most accurate reading with minimal changes as the aircraft experiences changes in roll, pitch or yaw.
Steep Turn A turn done at a constant angle of bank of 45 degrees
Storm A change in the atmosphere where wind speeds can reach 48-55 knots. Typically associated with strong gusty winds, lightning and precipitation.
Straight and Level (S&L) The phase of flight that makes up the majority of all flight. This is achieved by flying in a given direction at a constant altitude. The attitude of the aircraft can vary significantly based on the speed at which S&L is being maintained.
Stratosphere The second layer closest to the Earth's surface. The ozone layer can be found here
Streamlining The process of minimising the frontal face of an object thus reducing drag
Strobe Lights White lights situated on the wingtips of an aircraft that constantly flash
Strut A structural component that is common on high wing Cessna aircraft. The strut adds strengthening to aircraft structure.
Student Pilot A person who has not yet gained a pilot licence, but may be able to fly solo if they hold a current medical and have met the requirements for a solo flight.
S-Turn A snake-like turn of two half circles. Commonly used on final approach as a means of losing altitude if the aircraft position is too high
Surface Refers to the type of material used for the runway. Runways that need to accomodate large aircraft, need a certain amount of strength factor and are normally made of bitumen (tar), and smaller runways for smaller aircraft are most commonly grass, but can also be crushed shells, gravel and packed sand.
Surface Wind The direction and speed of the wind measure a few metres above the surface.
SMS Safety Management System. A system designed to identify hazards lower and manage risk for organisations, groups and businesses.

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