Some aircraft also are capable of using signals from a constellation of satellites to pinpoint their position. This is known as the Global Positioning System. Commercial aircraft are increasingly using it. GPS enables aircraft to operate, with the permission of Air Traffic Control, to operate safely off predetermined airways. This capability makes for more efficient operations and adds capacity to the aviation system.
Pilots control and steer aircraft in flight by manipulating panels on the aircraft wings and tail.
Those control surfaces are described in greater detail later in this chapter. In this phase of a flight, the pilot gradually brings the aircraft back toward the ground, by reducing engine power and speed, and thus the force of the lift. The so-called final approach begins several miles from the airport. By this point, Air Traffic Control has put the aircraft in a sequence to land, carefully separating it from all other aircraft headed for, or leaving, the same airport. The landing gear is lowered, slowing the plane further.