V1 Decision speed; below V1 take-off is abandoned if the critical engine fails, aircraft can stop safely within remaining runway; above V1 take-off can be continued safely
V2 Minimum take-off safety speed
VA Design manoeuvring speed
VC Design cruise speed
VD Design diving speed
VMO Maximum (permitted) operating speed; re: MMO
VNE Never exceed speed
VR Rotation speed, speed at which pilot raises nose of aircraft during take-off
VS Stalling speed
VAR Variation
variable geometry Aircraft capable of changing wing-sweep in flight
variable pitch Propellor which can change pitch of its blades in flight
VASI Visual approach slope indicator
VASIS Visual approach slope indicator system
VDU Video display unit
also:   Visual display unit
vertrep Vertical replenishment
VFR Visual flight rules
VG Variable geometry
VHF Very high frequency
VHSIC Very high speed integrated circuits
VIP Very important person
VL Vertical landing
VLA Very light aircraft; special section of the CS-23 / JAR 23 certification category, for VFR-only aircraft with a MTOW of 750 kg and a maximum of 2 persons on board
VLF Very low frequency
VLO Very low observable
VMC Visual meteorological conditions
VMS Vehicle management system
VOD Vertical on-board delivery
VOLMET Regular broadcast of meteorological information by ground station
VOR VHF omnidirectional radio range
vortex generator Small blade perpendicular to wing or tail surface; creates vortex in the boundary layer, keeping the boundary layer attached to the surface, thus improving control
vortillon Fence around underside of wing leading-edge; controls boundary layer direction
VP Variable pitch (propellor)
VPU Video processing unit
VSD Vertical situation display
VSI Vertical speed indicator
V/STOL Vertical / short take-off and landing
VTOL Vertical take-off and landing
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