V SPEEDS definitions

Vmcg. (Minimum control speed on the ground): The minimum speed at which an aircraft is defined

to be “controllable” (lateral excursion lower than 30 feet) with aerodynamic controls only after an

engine failure on the ground.

Vef – (Engine failure speed): the speed that the critical engine is assumed to fail. It may not be less

than Vmcg.

V1 (often referred to as “Decision Speed”): Must not be less than Vef plus the speed gained

 between when the engine failed and the pilot recognized the failure. This means that this speed is the

minimum speed at which an engine failure may occur and the pilot may continue the takeoff. At the

same time, V1 speed must not be greater than the speed at which a rejected takeoff can be initiated

and stop the airplane within the calculated accelerate-stop distance.

Vmu (Minimum unstick speed): Minimum airspeed at which airplane can safely lift off ground and

continue take-off. Because of the way this speed is determined, lift-off is not possible prior to

reaching this speed.

Vr (Rotation speed): Must be greater than V1 and greater than 1.05 Vmca and may not be less than

the speed that would allow reaching V2 before reaching a height of 35 feet above the takeoff surface.

This speed is selected so that the rotation begins at Vr and provides that Vlo occurs at a speed greater 

than VMU The rotation is continued at approximately 3 degrees per second until reaching the desired

 pitch attitude.

Vlo (Lift-off speed): Must be greater than 1.1 Vmu with all engines, or 1.05 Vmu with engine out.

Vmca (Minimum control speed in the air): Minimum airspeed at which, when the critical engine is

made inoperative, it is still possible to maintain control of the airplane and maintain stable, controlled

flight. [The rudder is used to compensate for the yaw moment caused by thrust asymmetry. There is a

minimum speed at which full rudder will be necessary, in order to fly a constant heading with level

wings. To reduce sideslip, this speed can be reduced even more, if the aircraft is banked on the live

engine’s side. The lower the speed, the greater the necessary bank angle. The speed that corresponds

to a 5-degree bank angle is defined as Vmca.]

V2min (Minimum take-off safety speed): Must be greater than 1.1 Vmca and 1.2 Vs, the stalling

speed in the take-off configuration.

V2 (Take-off safety speed): May not be less than V2min and may not be less than Vr plus the speed

gained before reaching a height of 35 feet above the takeoff surface. [If one engine is lost before

reaching V2, then the initial climb is flown at V2. If thrust is lost at a speed between V2 and V2+10,

then the current speed is maintained, to ensure the most efficient climb speed. It is not necessary to

increase pitch, in order to reduce the speed to V2, when a higher speed has already been reached.]