Expert: Ray Wilkinson - 2/10/2009

Question
On what all factor the Decision Speed of an aircraft decided?Is this parameter depends upon the load carrying capacity of an aircraft?

Answer
Hi

Decision speed (usually known as V1) is the lowest speed at which the aircraft is committed to taking off - the option of stopping is no longer available because there isn't enough runway left. It's based on the length of runway and the friction on the runway surface, the weight of the aircraft compared to its maximum takeoff weight, and various other factors relating to the design of the aircraft such as the effectiveness of the brakes. The option to stop instead of taking off (prior to V1) assumes that the aircraft will stop using just the brakes - no reverse thrust is assumed because if an engine has failed the pilots will not have any thrust reversers available. Above V1, any engine failure will still require the aircraft to take off, and the crew will then decide whether to go around for an emergency landing or continue the flight.