Glide Ratio

Glide ratio tells you how efficiently an aircraft converts altitude into forward travel while descending with no thrust. It works because the aircraft’s lift and drag determine the flight path angle: more lift relative to drag lets the aircraft move farther horizontally before losing a given amount of height. A higher glide ratio means the aircraft can cover more ground from the same starting altitude.

Use this formula when estimating how far a glider, airplane, or drone can travel if the engine fails or power is reduced. It is also useful for planning descent distances, emergency landing reach, and comparing the gliding efficiency of different aircraft.

• Using slant distance instead of horizontal forward distance
• Putting altitude lost in the numerator and distance in the denominator
• Assuming glide ratio includes engine power rather than unpowered descent