What is a controlled descent with the engine disengaged called?

In the context of aviation, the term for a controlled descent with the engine disengaged is known as autorotation. This is a specific maneuver usually performed by helicopters. During autorotation, the pilot allows the aircraft to descend and rotate in a controlled manner without engine power, utilizing the upward airflow through the rotor blades to maintain rotor speed. This maneuver is crucial for safely landing a helicopter in the event of an engine failure, as it allows for a controlled descent rather than a free fall.

The process of autorotation involves adjusting the collective pitch of the rotor blades to manage the descent rate and ensure lift is maintained as the helicopter approaches the ground. Mastery of autorotation is essential for pilots, as it ensures the ability to perform an emergency landing safely while maintaining control over the descent trajectory.