What is the primary force that causes an airplane to turn?

An airplane turns primarily due to the horizontal component of lift. When an aircraft banks or tilts its wings during a turn, the lift vector, which normally acts straight upward, is tilted along with the airplane. This results in both a vertical component of lift that supports the weight of the aircraft and a horizontal component of lift that pulls the airplane towards the center of the turn.

As the pilot banks the aircraft, the horizontal component of lift generates the necessary lateral acceleration required to change the direction of flight, enabling the airplane to execute a turn. The greater the bank angle, the larger the horizontal component of lift, allowing for tighter turns.

Centrifugal force, though often perceived during a turn, is actually a result of inertia rather than a force acting on the aircraft. It is the feeling of being pushed outward during a turn, but it does not contribute to the actual turning motion of the aircraft.

The vertical component of lift is responsible for maintaining altitude, not for turning. While it is crucial for supporting the aircraft’s weight, it does not assist in changing the aircraft’s direction of flight. Therefore, understanding the role of the horizontal component of lift is essential for grasping how airplanes maneuver during a turn.