V1
Takeoff decision speed. Engine failure below V1 takeoff must be aborted. Engine failure at or above V1, takeoff must be continue, accelerate to Vr, rotate, then accelerate to V2.
V2
Takeoff safety speed. Best climb gradient speed. Best climb gradient speed per mile with most critical engine inoperative are guaranteed a 2.4% climb gradient (24ft per 1,000ft forward). Minimum speed to be maintained until at least 400ft AGL.
V2MIN
Minimum takeoff safety speed. Usually 1.2 times stall speed in takeoff configuration.
VA
Design Maneuver Speed. Speed decreases as weight decreases.
VABE
Maximum Air-Brake Extension
VABO
Maximum speed for Air Brake Operation
VAC
Missed approach climb speed
VAP
Approach target speed. VREF + configuration & wind factor.
VB
Design speed for maximum gust intensity. Turbulent air penetration speed.
VC
Design cruising speed. Speed the aircraft was designed to cruise at.
VD
Design diving speed. Aircraft designed to be capable of diving at this speed in smooth air.
VDEC
Accelerate/Stop decision speed.
VDF/MDF
Demonstrated flight diving speed. VDF=KIAS MDF=% mach.
VEF
Speed at which critical engine is assumed failed during takeoff.
VENR
Enrollee climb speed with critical engine inoperative. Use above 1500 AGL
VF
Design flap speed. Flaps designed to be operated at this maximum speed.
VFC
Maximum speed for undesirable flight characteristics. Instability could develop beyond pilot's capability.
VFE
Maximum flap extension speed.
VFR
Minimum flap retraction speed.
VFS
Final Segment Speed. Jets accelerate to at 400ft AGL with critical engine inoperative.
VFTO
Final takeoff speed. End of the takeoff path, en route configuration, one engine inoperative.
VH
Maximum speed in level flight with max continuous power.
VLE
Maximum landing gear extended speed
VLLE
Maximum landing light extended speed
VLLO
Maximum landing light operating speed
VLO
Maximum landing gear operating speed. Extend/retract.
VLOF
Lift off speed. Speed at which aircraft becomes airborne.
VMC
Minimum controllable speed with critical engine (usually the left) inoperative out of ground effect.
VMCG
Minimum speed necessary to maintain directional control following an engine failure during the takeoff roll while still on the ground.
VMO/MMO
Maximum operating limit speed. VMO=KIAS MMO=% mach dealing with critical mach number.
VMU
Minimum unstuck speed. Slowest speed at which an aircraft can become airborne.
VNE
Never exceed speed.
VNO
No go there. Maximum structural cruising speed.
VR
Rotation speed
Vref
Calculated reference speed for final approach. Usually 1.3Vso or higher.
Vs
Stall speed
Vs1
Stall speed in a specific configuration
Vso
Stall speed in landing configuration
Vsse
Minimum safe single engine speed
Vwwo
Maximum windshield wiper operating speed
Vx
Best angle of climb speed - greatest gain in altitude in the shortest possible horizontal distance.
Vxse
Best single engine angle of climb speed
Vy
Best rate of climb speed - greatest gain in altitude in the shortest possible time.
Vyse
Best single engine rate of climb speed