Definition
The airspeed at which an aircraft, during the takeoff roll, develops enough lift to leave the runway and become airborne. It is specific to the aircraft type, weight, configuration, and conditions, and is published in the aircraft flight manual.
Plain English
The speed at which the airplane has enough lift to fly off the runway during takeoff.
Context Anchor
Seen in takeoff, departure, and approach-to-stall discussions, especially when describing the low-speed condition just after the aircraft becomes airborne.
Why Pilots Care
Rotating or pulling back too early -- before reaching liftoff speed -- can cause the aircraft to lift briefly, settle back, or enter a stall close to the ground. Knowing the correct liftoff speed for the aircraft and conditions is essential for a safe, predictable takeoff.
Grounding Statement
At liftoff speed, the airplane has just enough lift to leave the ground, not a large extra cushion of speed.
Intuition Check
Liftoff speed does not mean a safe climbing speed. It only means the aircraft has reached the speed where it can first become airborne.
Example Sentence 1
He held the airplane on the runway until it reached liftoff speed, then eased back on the yoke.
Example Sentence 2
Performance calculations confirmed the required runway length based on the expected liftoff speed.