This condition is accomplished by using reversible pitch propellers or thrust reversers. For ground roll during landing the thrust force is retarding. The airplane drag may be increased by setting the flaps for maximum drag. Another favorite braking device used by military airplanes is the parachute which is opened at touchdown. On board aircraft carriers, the usual landing brake is mechanical in the form of the arresting hook on the airplane engaging a cable laid across the flight deck.
Deceleration is exceedingly swift and the airplane is subjected to large structural forces.
There are ample cases of curved flight paths. These cases include the climbing and descending turns, maneuvers in combat and aerobatics. One of the basic maneuvers required to change the flight-path heading is the constant altitude banked turn. In the previous discussions of motions of an airplane, accelerations due to a change of direction of flight were insignificant. But in a turn they acquire added significance.