In aviation terminology, a rejected takeoff (RTO) or aborted takeoff is the situation in which it is decided to abort the takeoff of an airplane. There can be many reasons for deciding to perform a rejected takeoff, but they are usually due to suspected or actual technical failures, such as an engine failure, fire, incorrect configuration, aircraft controllability or environmental conditions such as windshear.
A rejected takeoff is normally performed only if the aircraft's speed is below the takeoff decision speed known as V1, which for larger multi-engine airplanes is calculated before each flight. Below the decision speed, the airplane should be able to stop safely before the end of the runway. Above the decision speed, the airplane may overshoot the runway if the takeoff is aborted, and, therefore, a rejected takeoff is normally not performed above this speed, unless there is reason to doubt the airplane's ability to fly. If a serious failure occurs or is suspected above V1 but the airplane's ability to fly is not in doubt, the takeoff is continued despite the (suspected) failure and the airplane will attempt to land again as soon as possible.
Single-engine aircraft will reject any takeoff after an engine failure, regardless of speed, as there is no power available to continue the takeoff. Even if the airplane is already airborne, if sufficient runway remains, an attempt to land straight ahead on the runway may be made. This may also apply to some light twin engine airplanes.
Before the takeoff roll is started, the autobrake system of the aircraft, if available, is armed. The autobrake system will automatically apply maximum brakes if throttle is reduced to idle or reverse thrust during the takeoff roll once a preset speed has been reached.
An RTO is usually seen as one of the hardest tests an airplane has to undergo for its certification trials. The RTO test is performed under the worst possible conditions; i.e. with fully worn out brakes, the plane loaded to maximum takeoff weight and no use of thrust reversers. During an RTO test most of the kinetic energy of the airplane is converted to heat by the brakes, which may cause the fusible plugs of the tires to melt, causing them to deflate. Small brake fires are acceptable as long as they do not spread to the airplane body within five minutes (the maximum likely time for arrival of the airport fire fighters).