SUT  (1) Autothrottle Servo 
(2) Stabilizer Trim Servo 
SV  Space Vehicle 
SVC  Service 
SVO  Servo 
SVT  Servo Throttle 
SVU  Satellite Voice Unit 
S/W  Software 
sys  System 
T 
TA  Traffic Advisory 
TAC  (1) Test Access Control 
(2) Thrust Assymetry Compensation 
TACAN  Tactical Air Navigation System Provides azimuth and 
distance information to an aircraft from a fixed 
ground station (as opposed to DME providing only 
distance information). 
Tach  Tachometer 
TACIU  Test Access Control Interface Unit 
TAG  AEEC Technical Advisory Group 
TAI  Thermal Anti-Icing 
Target  An aircraft within the surveillance range of TCAS. 
TAS  True Airspeed 
TAT  (1) Total Air Temperature. The air temperature includ-
ing heat rise due to compressibility. 
(2) True Air Temperature 
TATCA  Terminal Air Traffic Control Automation 
TAU  TAU is the minimum time a flight crew needs to dis-
cern a collision threat and take evasive action. It rep-
resents the performance envelope (speed and path of 
aircraft) divided by the closure rate of any intruder 
aircraft (TCAS). 
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TBB  Transfer Bus Breaker 
TBD  To Be Determined 
TBS  To Be Supplied 
TC  Type Certificate 
TCA  Terminal Control Area 
TCAS  Traffic Alert Collision Avoidance System 
TCAS I  A baseline system that provides a warning (TA) to the flight crew of the presence of another aircraft (poten-tial collision threat) within the surveillance area. No avoidance maneuver is suggested. 
TCAS II  A collision avoidance system providing traffic infor-mation (within approximately 30 nmi of the aircraft) to the flight crew, in addition to the resolution advi-sories (RA) (for vertical maneuvers only). A TCAS II-equipped aircraft will coordinate with TCAS II-equipped intruder aircraft to provide complementary maneuvers. 
TCC  Turbine Case Cooling