How does an aircraft fly?

An aircraft flies when the forces acting on it are balanced in a way that allows it to remain airborne. Its wings generate lift, the engines provide thrust, drag opposes the aircraft's motion, and weight acts downward due to gravity.

An aircraft flies because its wings interact with the air to produce lift. The shape of the wing, known as an aerofoil, causes the airflow around the wing to produce an aerodynamic force with an upward component called lift. The engines produce thrust, which moves the aircraft forward through the air. As the aircraft moves, it experiences drag, which acts opposite to its direction of motion. Weight, caused by gravity, acts downward. For steady, level flight, lift is approximately equal to weight and thrust is approximately equal to drag. By controlling these forces, the pilot can make the aircraft climb, descend, accelerate, decelerate, or maintain level flight.

Lift acts generally upward. Weight acts downward. Thrust moves the aircraft forward. Drag opposes forward motion. The aerofoil-shaped wing is fundamental to producing lift. The four principal forces of flight are lift, weight, thrust and drag. Aircraft performance and flight path depend on the interaction and control of these forces.