S/L or s/l Sea level
s/n Serial number
also:   Since new
s/o Since overhaul
SAAHS Stability augmentation and altitude hold system
SAC Strategic Air Command (USAF)
SACEUR Supreme Allied Commander Europe (NATO)
SACLOS Semi-automatic command to line-of-sight (GW guidance method)
safe life Time, after which a part should be replaced, even if not apparently defective
SAHRS Standard attitude & heading reference system
SALT Strategic Arms Limitations Treaty
SAM Surface-to-air missile
SAR Search and rescue
also:   Synthetic aperture radar
also:   Semi-active radar
SARH Semi-active radar homing
SAS Stability augmentation system
also:   Special Air Service (UK)
SAT Satellite
satcom Satellite communications
satnav Satellite navigation
saw-tooth re: dog-tooth
SB Service Bulletin
SBAC Society of British Aerospace Companies
SCAS Stability and control augmentation system
SDI Strategic Defence Initiative (US); aka 'Star Wars'
SE Single Engine
SEAD Suppression of enemy air defenses
seat pitch Distance between back of one seat and the same point on back of seat in front
semi-active Missile guidance system; missiles homes on radiation reflected by the target but emitted from the launch aircraft
semi-monocoque Construction in which most of the structural strength is in the skin and directly underlying stringers and frames
senso Sensor operator
SEP Specific excess power
also:   Single engine piston
service ceiling Altitude at which maximum rate of climb is 100 ft/min
servo Device augmenting pilot input, usually to move a control surface
SFAR Special federal aviation regulations (FAA)
SFC Specific fuel consumption; amount of fuel used per unit of power per unit of time
also:   Surface
SFW Sensor fused weapon
SHAPE Supreme Headquarters Allied Powers Europe (NATO)
SHF Super high frequency
Shorad Short range air defence
shp Shaft horsepower; power at engine output shaft
SI Specific impulse (rocket performance parameter)
side-arm controller re: sidestick
sidestick Primary aircraft control; replacing traditional control stick or control column with a short handgrip beside the pilot(s)
sigint Signals intelligence
single shaft Gas-turbine powerplant in which all compressor and turbine stages are mounted on a single shaft
SIP Systems Improvement Programme
SITA Société Internationale de Télécommunications Aéronautiques; airlines worldwide telecommunications and information services
SLAR Side looking airborne radar
slat Auxiliary aerofoil device; prevents airflow breakaway on wing or tail
SLEP Service life extension programme (US)
also:   Service life enhancement programme
slew wing re: oblique wing
SLR Side-looking radar
SLRR Side-looking reconnaissance radar
SMOH Since major overhaul
SMS Stores management system
SMTI Selective moving target indicator
SMTS Space and Missile Training Squadron (USAF)
snap-down Ability to intercept a low flying target from a significantly higher altitude
SOF Special Operations Forces (US)
soft target Target which is not hardened or armoured
SOG Special Operations Group (US)
SOM Stand-off missile
sonar Sound navigation and ranging
SOP Standard operating procedure
SOR Specific operational requirement
SOS Stabilised optical sight
also:   Special Operations Squadron (USAF)
SOW Stand-off weapon
also:   Special Operations Wing (USAF)
SPICUS Single pilot-in-command under supervision
SPKR Speaker
splitter Plate dividing airflow (usually engine inlet)
spoiler Moveable surface on wing; when open reduces lift and increases drag
SPTW Support Wing (USAF)
SR Short range
also:   Strategic reconnaissance (US)
SR(A) Staff requirement (Air) (UK)
SRA Surveillance radar approach
SRAAM Short range air-to-air missile
SRW Strategic Reconnaissance Wing (USAF)
SRZ Special Rules Zone
SSB Single sideband
SSR Secundary surveillance radar
SST Supersonic transport
st Static thrust; thrust of jet or rocket engine when stationary
STA Supplementary Type Approval
stabiliser Any fixed tail surface
stalling speed Airspeed at which lift of wing suddenly decreases
stall strips Strips on wing leading edge to induce stall at that specific point
starboard Right side, while looking forward
START Strategic Arms Reduction Treaty
also:   Strategic Arms Reduction Talks
STC Supplemental Type Certificate
STD or std Standard
STE Special test equipment
stick-pusher Stall-prevention device; forces the control stick forward when stalling Angle of Attack is approached, reducing the Angle of Attack
stick-shaker Stall-warning device; shakes the control stick quickly fore&aft through small angle when stalling Angle of Attack is approached, as a warning to the pilot
STOL Short take-off and landing
store Any weapon or equipment not permanently attached to aircraft
STOVL Short take-off and vertical landing
strake Long narrow surface, aligned with airflow and perpendicular to fuselage skin
strobe Flashing anti-collision beacon
STS Status
supercritical A wing which has an unusually high critical Mach No. for its sweep angle and t/c; special highly advanced aerofoil
SUU Suspension Unit Underwing (USAF)
SW Strategic Wing (USAF)
sweep back Backward inclination of wing relative to fuselage; usually measured at quarter chord
swing wing Variable geometry wing
SWIP Systems weapons integration programme
# - A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z