Glide Ratio

Glide ratio tells you how far an aircraft can travel forward while losing a given amount of height in a steady glide with no engine thrust. It works because the aircraft’s weight is balanced by lift and drag, and the ratio of lift to drag determines how efficiently the aircraft converts altitude into forward distance. A higher lift-to-drag ratio means less energy is wasted to drag, so the aircraft glides farther for the same altitude loss.

Use this formula when estimating glide performance, planning engine-out landings, or comparing how efficiently different aircraft, gliders, or wing configurations descend. It is also useful in aviation training and flight planning to judge whether a landing area is reachable from a given altitude.

• Using glide ratio during powered flight, when engine thrust changes the result
• Confusing units and mixing nautical miles, kilometres, feet, and metres without converting consistently
• Assuming glide ratio gives actual range in all conditions without accounting for wind, aircraft configuration, or airspeed