V1

V1 (Decision Speed) is the maximum speed during takeoff at which the pilot can still safely abort and stop the aircraft within the remaining runway. Beyond V1, the takeoff must continue because there may not be enough runway remaining to stop. It is the most critical speed in the takeoff sequence.

• Calculated for each takeoff based on weight, temperature, pressure altitude, runway length, slope, wind, and surface condition
• Below V1: reject the takeoff for any engine failure or critical malfunction
• At or above V1: continue the takeoff even with one engine failed
• V1 must not exceed VR (rotation speed)