‘V-speeds’ Shorthand notation of significant speeds within an aircraft's flight envelope (see table).
V1 Decision speed, up to which it should be possible to abort a take-off after failure of the critical engine and stop safely within the remaining runway length. After reaching V1 the take-off must be continued.
V2 Minimum take-off safety speed.
VA Design manoeuvring speed. The speed below which abrupt and extreme control movements are possible (though not advised) without exceeding the airframe’s limiting load factors.
VB Design speed for maximum gust intensity.
VC Design cruising speed.
VD Design diving speed.
VDF Maximum demonstrated diving speed. Also MDF, maximum demonstrated Mach No. in a dive.
VE Maximum speed at which landing gear (or other item) may be extended or retracted (cycled).
VFE Maximum flap extension speed (top of white arc on ASI).
VH Maximum level-flight speed with maximum continuous power.
VLE Maximum speed with landing gear extended.
VMCA Minimum control speed (air). Minimum speed at which directional control of a multi-engined aircraft can be maintained after failure of critical engine (in effect, the lowest speed at which the aircraft possesses sufficient rudder authority to counteract the yaw induced by asymmetric thrust).
VMU Minimum unstick speed.
VNE Never exceed speed.
VMO Maximum operating speed. Also MMO, maximum operating Mach No.
VNO Normal operating speed. The maximum structural cruising speed allowable for normal operating conditions.
VR Rotation speed, at which to raise the nose for take-off.
VRA Rough air speed. Maximum recommended airspeed for penetrating turbulent air.
VREF Any reference or ‘bug’ speed, typically quoted for approach speeds.
VSO Stalling speed at maximum take-off weight, in landing configuration with flaps and landing gear down, at sea level, ISA conditions (bottom of white arc on ASI). Also VS, stalling speed ‘clean’, and VS1, stalling speed for a given configuration other than ‘clean’.
VSSE Minimum speed for deliberate shutting down of one engine for purposes of asymmetric flight training.
VX Best angle of climb speed on all engines. Sometimes (UK usage) V%.
VXSE Best engine out angle of climb speed.
VY Best rate of climb speed on all engines.
VYSE Best engine-out rate of climb speed. Sometimes V%SE.
VZRC Zero rate of climb speed (on one engine, where drag of inoperative engine reduces climb gradient to zero).
variable geometry Capable of grossly changing shape in flight, especially by varying sweep of wings.
variable pitch Propeller with its blades held in rotary bearings in the hub, so that pitch (of all blades in unison) can be altered in flight. See constant speed: compare ground- and flight-adjustable pitch.
VC Vickers Commercial.
VDU Video (or visual) display unit.
vectored Capable of being pointed in different directions.
vertrep Vertical replenishment.
VFR Visual flight rules.
V-G Variable Geometry (which see).
VHF Very high frequency.
VIP Very Important Person.
VLF Very low frequency (area-coverage navaid/radio transmission band).
VMS Vehicle management system.
VOR VHF omnidirectional range (network of VHF radio beacons each providing to/from bearing).
vortex generators Small blades attached to wing and tail surfaces to energise local airflow and improve control.
vortillon Short-chord fence (particularly on MD-80 series) ahead of and below leading-edge.
VSI Vertical speed (climb/descent) indicator.
V/STOL Vertical/short take-off and landing.
VTA Voenno-Transportnaya Aviatsiya.
VTO Vertical Take-Off.
VVS Voenno-Vozdushnye Sili (Russian air force).