Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's thrust so that it is directed forward, rather than backward. Reverse thrust acts against the forward travel of the aircraft, providing deceleration. Thrust reverser systems are featured on many jet aircraft to help slow down just after touch-down, reducing wear on the brakes and enabling shorter landing distances. Such devices affect the aircraft significantly and are considered important for safe operations by airlines. There have been accidents involving thrust reversal systems such as Lauda Air Flight 004.
Reverse thrust is also available on many propeller-driven aircraft through reversing the controllable-pitch propellers to a negative angle. The equivalent concept for a ship is called astern propulsion.
