TM 55-1510-220-10
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.
1. AIRSPEED TERMINOLOGY.
CAS
Calibrated airspeed is indicated airspeed corrected for position and instrument
error.
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
compressibility effects.
Va
Maneuvering speed is the maximum speed at which application of full available
aerodynamic control will not over stress the aircraft.
Vf
Design flap speed is the highest speed permissible at which wing flaps may
be actuated.
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
determined in accordance with Federal Aviation Regulations.
Aircraft
Certification conditions include one engine becoming inoperative and
windmilling; a 50 bank towards the operative engine; takeoff power on operative
engine; landing gear up; flaps up; and most rearward CG. This speed has been
demonstrated to provide satisfactory control above power off stall speed (which
varies with weight, configuration, 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.
B-1
