Gliding

Gliding is a mode of locomotion or flight that relies on lift and little or no propulsion. In nature, many species glide to move between locations or to evade predators, using membranes, extended limbs, or other surfaces to catch the air. In human aviation, gliding refers to unpowered flight in a sailplane or glider designed for high efficiency and long-distance travel.

Natural gliders include flying squirrels, colugos, gliding lizards, and some frogs and snakes. They typically launch from height or jump from trees, use gravity for initial speed, and rely on rising air or favorable winds to extend their travel.

In human gliding, aircraft have long, high-aspect-ratio wings and are unpowered. They are launched by ground-based winches, aerotow, or, in the case of self-launching gliders, its own engine. Once aloft, pilots exploit rising air and stable winds to stay airborne and cover distance without engine power.

Pilots seek specific lift sources such as thermals (columns of warm air), ridge lift along hills and ridges, and atmospheric waves over mountains. The efficiency of a glider is described by its glide ratio—the forward distance traveled for each unit of altitude lost—with modern sailplanes typically achieving about 40:1 to 60:1 in favorable conditions.

Gliding is organized through clubs and associations and practiced worldwide as sport, recreation, and training for powered aviation. Activities include cross-country flights, thermal hunting, and competitive tasks that test navigation, weather interpretation, and precision in performance.