Assisted take-off

In aviation, assisted takeoff is any external system for helping aircraft (more specifically fixed-wing aircraft) to become airborne (take off) for flight, as opposed to doing so conventionally using strictly their own propulsion. The reasons assistance might be needed include: the combined weight of the aircraft and its payloads exceeding the maximum takeoff weight; insufficient enginepower by design or malfunction, insufficient available runway length (such as on the flight deck of an aviation warship), or a combination of the above. Assisted takeoff is also required for gliders, which do not have any engine and thus are unable to propel themselves for takeoffs.