A tool used to determine the horizontal distance an aircraft can travel for every unit of altitude lost, this digital aid employs a simple mathematical formula dividing horizontal distance by vertical distance. For example, a result of 10 signifies the aircraft can glide 10 units horizontally for every 1 unit of descent. This ratio is a crucial performance metric for gliders, sailplanes, and even powered aircraft in engine-out scenarios.
Understanding this aerodynamic principle is fundamental for flight planning, especially for unpowered aircraft. It allows pilots to assess potential landing sites within reach in case of emergencies or to optimize cross-country flight paths by leveraging rising air currents. Historically, pilots relied on slide rules and charts to make these calculations. Modern digital tools provide significantly increased speed and accuracy, contributing to safer and more efficient flight operations.