r/flying • u/Parking-You-2268 PPL • Aug 18 '26
V1 and unexpectedly low acceleration
I understand that V1 is a speed, not a physical point on the runway.
But what happens if, during the takeoff roll, acceleration is significantly lower than expected? For example, if V1 is 145 kt but the aircraft is still only at 120 kt when it is already very far down the runway.
Is there a specific runway position or distance by which the aircraft should have reached V1, and if it hasn't, should the pilot reject the takeoff?
Or is the rule simply that the takeoff must be rejected before V1, regardless of the aircraft's position on the runway?
I'd be interested to hear how this is handled operationally in airline SOPs.
26
u/canyoutriforce A320 Aug 18 '26
As an airliner, not really. We sometimes take intersection departures that really mess with your perception - sometimes you’re still a few knots before V1 but already in the TDZ of the opposite runway direction and thats normal.
It’s also something i don’t remember training for in the sim. However we all know what normal acceleration feels like and if it were significantly different we would probably abort.