SRAM  Static Random Access Memory 
SRD  Systems Requirements Document 
SR  Service Request 
SRU  Shop Replaceable Unit 
SSB  Single Sideband. An AM signal that has a reduced car-rier, with the power applied to a single sideband. Since the bandwidth of the information-carrying sig-nal is reduced,a better signal-to-noise ratio is obtained at the receiver. 
SSCVR  Solid State Cockpit Voice Recorder 
SSEC  Static Source Error Correction 
SSFDR  Solid State Flight Data Recorder 
SSM  Sign Status Matrix 
SSR  Secondary Surveillance Radar. A radar-type system that requires a transponder to transmit a reply signal. 
SSSC  Single Sideband Suppressed Carrier. A SSSC signal is a band of audio intelligence frequencies which have been translated to a band of radio frequencies with-out distortion of the intelligence signal. 
SSU  Subsequent Signal Unit 
sta  Station 
STAB  Stabilizer 
Standard Atmosphere  Represents the mean or average properties of the atmosphere. At sea level static pressure is 29.92 InHg and temperature is +15° C. 

Standby Mode A DME mode that applies power to the DME RT but the unit does not transmit.
STAR  Standard Terminal Arrival Routes
STARS  Standard Terminal Automation Replacement System
Static Ports  Flush-mounted openings in the skin of the aircraft fuselage used to sense static pressure.
Static  Ambient atmospheric pressure or static pressure is 
Pressure  the force per unit area exerted by the air on the sur 
face of a body at rest relative to the air. 
Static Ram  RAM constructed of bistable transistor elements. 
Memory cells do not require refreshing (see “Dynamic 
RAM”). 
Static Source  A correction applied to static source pressure mea 
Error (SSEC)  surements to partly or completely correct for pres 
sure errors which are caused by airflow changes. It is 
computed as a function of Mach and altitude based 
on measured errors for a particular static system 
STBY  Standby 
STC  (1) Sensitivity Time Control. A control circuit used in 
radar applications to control receiver gain with 
respect to time. 
(2) Supplemental Type Certificate 
STCA  Short Term conflict Alert 
STCM  Stabilizer Trim Control Module 
STD  Standard 
STP  Standard Temperature and Pressure 
STS  Stable Time Subfield 
STVS  Small Tower Voice Switch 
SUA  Special Use Airspace 
SUL  Yaw Damper Actuator 
SUO  (1) Aileron/Elevator/Rudder Servo