Minimum Sink Speed

Minimum sink speed is the airspeed at which an unpowered aircraft descends most slowly — producing the lowest rate of sink in feet per minute. It corresponds to the airspeed that generates the minimum power required to sustain flight.

Minimum Sink vs. Best Glide

Minimum sink speed provides the maximum time aloft; best glide speed provides the maximum horizontal distance. Minimum sink speed is always slower than best glide speed. For an engine failure, best glide (range) is normally preferred because it maximizes the distance available to reach a landing area. Minimum sink (endurance) is useful when circling to lose altitude over a landing site or when buying time to troubleshoot a problem.

Related Terms

See also: Glide Speed for Endurance, Glide Speed for Range.