11:56AM EST October 1. 2012 - Question: When a plane is speeding down the runway, what determines when liftoff occurs. Is this the pilot's decision?
--submitted by reader Jeff, New York City
Answer: The speed at which the airplane lifts off is determined by the weight, temperature, altitude of the runway and the slat/flap setting. Before beginning the takeoff roll, the crew has calculated the speed at which there is no longer an option to stop on the runway (known as V1), the speed at which the nose is raised (known as Vr) and the speed to climb if an engine fails (known as V2). The airplane becomes airborne (lifts off) shortly after the rotation speed and the nose is raised.