V2, often referred to as the takeoff safety speed, represents the minimum speed at which the aircraft can safely continue the takeoff following an engine failure, maintaining a positive rate of climb. V2 is the target speed to be attained with one engine inoperative.
Why do we need to calculate V2?
Flying close to stall speed or Vmca is really unsafe. V2 is faster than both of this speed. V2 is the lowest calculated speed which enable aircraft to have sufficient excess thrust to climb above minimum acceptable climb gradient requirements. In the event of engine failure, V2 must be flown until the aircraft reaches 400 ft.
V2 Min
V2Min is the minimum take-off safety speed, with critical engine operative.
- V2Min is greater than equal to 1.13 Vsr
- V2Min is greater than equal to 1.1 Vmca
V3 Speed
V3 is the steady initial climb speed with all engine operating. It is generally 10-15 knots higher than V2.
Take-off with increased V2 Speed
Taking off with an increased V2 speed is a strategic approach used when the takeoff weight is limited by climb gradient requirements (Climb Limit Mass). This situation typically arises when climb performance is poor, significantly restricting the aircraft’s potential payload.
Increasing V2 brings it closer to the best climb angle speed (Vx). While V2 is the minimum speed that allows the aircraft to have sufficient excess thrust to meet the minimum acceptable climb gradient, moving V2 closer to Vx improves climb performance. This adjustment is possible if the runway length permits, as a longer runway allows the aircraft to achieve a higher unstick speed, followed by a higher V2. As a result of the improved climb performance, climb limit mass can be increased.
