TM 55-1510-219-10
APPENDIX B
ABBREVIATIONS AND TERMS
For the purpose of this manual, the following abbreviations and terms apply. See appropriate technical
manuals for additional terms and abbreviations.
AIRSPEED TERMINOLOGY.
CAS
Calibrated airspeed is indicated airspeed corrected for position and instrument er-
ror.
FT/MIN
Feet per minute.
GS
Ground speed, though not an airspeed, is directly calculable from true airspeed if
the true wind speed and direction are known.
IAS
Indicated airspeed is the speed as shown on the airspeed indicator and assumes no
error.
KT
Knots.
TAS
True airspeed is calibrated airspeed corrected for temperature, pressure, and com-
pressibility effects.
Va
Maneuvering speed is the maximum speed at which application of full available
aerodynamic control will not overstress the aircraft.
Vf
Design flap speed is the highest speed permissible at which wing flaps may be actu-
ated.
Vfe
Maximum flap extended speed is the highest speed permissible with wing flaps in
a prescribed extended position.
Vle
Maximum landing gear extended speed is the maximum speed at which an aircraft
can be safely flown with the landing gear extended.
Vlo
Maximum landing gear operating speed is the maximum speed at which the landing
gear can be safely extended or retracted.
Vlof
Lift off speed (takeoff airspeed).
Vmca
The minimum flight speed at which the aircraft is directionally controllable as deter-
mined in accordance with Federal Aviation Regulations. Aircraft Certification con-
ditions include one engine becoming inoperative and windmilling; a 5° bank to-
wards the operative engine; takeoff power on operative engine; landing gear up;
flaps up; and most rearward CG. This speed has been demonstrated to provide sat-
isfactory control above power off stall speed (which varies with weight, configura-
tion, and flight attitude).
Vmo
Maximum operating limit speed.
Vne
Never exceed speed.
Vr
Rotation speed.
Vs
Power off stalling speed or the minimum steady flight speed at which the aircraft
is controllable.
Vso
Stalling speed or the minimum steady flight speed in the landing configuration.
Vsse
The safe one-engine inoperative speed selected to provide a reasonable margin
against the occurrence of an unintentional stall when making intentional engine
cuts.
B-1
