Definition
The calibrated airspeed at which the airplane first becomes airborne during the takeoff roll, meaning the main wheels leave the runway surface.
Plain English
The speed at which the wheels actually come off the ground during takeoff.
Context Anchor
Seen in takeoff performance, aircraft certification, and discussions of takeoff speeds.
Derivation
The 'V' comes from the French 'vitesse,' meaning speed — used throughout aviation for defined airspeeds. 'LOF' stands for 'lift-off.' So VLOF literally reads as 'lift-off speed.'
Why Pilots Care
It confirms the airplane has enough speed to climb safely away from the runway after rotation.
Intuition Check
Do not assume VLOF is the same as the speed where the pilot begins raising the nose. VLOF is the speed when the airplane actually leaves the runway.
Example Sentence 1
After rotating, the airplane accelerated through VLOF and the main wheels lifted cleanly off the runway.
Example Sentence 2
On a short runway the calculated VLOF must be reached before the end of the available takeoff distance.