What defines controlled flight in aviation?

Controlled flight in aviation is defined by the ability to maintain stability and desired flight paths, which is essential for safe and effective maneuvering of the aircraft. Pilots achieve controlled flight through active management of the aircraft's controls—utilizing the ailerons, elevators, and rudder to achieve the desired altitude, speed, and direction.

Maintaining stability means that the aircraft can remain in equilibrium despite various disturbances, such as wind gusts or turbulence. A stable flight path ensures that the aircraft can respond appropriately to pilot inputs and environmental changes, allowing for precise navigation and adherence to flight plans.

The other options highlight scenarios that do not represent controlled flight. Autopilot systems, while useful, are merely tools that can assist in maintaining controlled flight but do not define it. An uncontrolled descent following a stall represents a loss of control, and flight resulting from passive atmospheric conditions lacks the active management of flight dynamics required for controlled flight. Thus, maintaining stability and following the desired flight paths distinctly characterize controlled flight in aviation.