Glide Distance Calculator

For an engine-out emergency, this calculator turns altitude and your aircraft's glide ratio into a usable range estimate. The core relationship is simple geometry: still-air glide distance equals altitude above ground level divided by 6,076.12 feet per nautical mile, times the effective glide ratio (lift-to-drag, or L/D) — a 9:1 glider descending from 5,000 feet AGL travels roughly 45,000 feet, or about 7.4 nautical miles, in calm air. Two corrections adjust that baseline. First, best-glide airspeed scales with the square root of the ratio between actual weight and the POH's reference weight, since a lighter airplane needs a slower best-glide speed to hold the same optimal angle of attack — descent rate and time-to-ground follow from that adjusted speed and the effective glide ratio alone, with no wind term involved.

Second, any sustained bank angle degrades the effective glide ratio by a factor of the cosine of the bank angle, because turning trades some lift for turning force rather than for holding altitude; the calculator also reports the resulting load factor (1 divided by cosine of bank), which climbs quickly past 30-40 degrees of bank. Wind does not change how long the glide takes to reach the surface in this model — descent rate and time-to-ground depend only on airspeed and glide ratio — but it does change how far you travel while descending: the calculator holds that time-to-ground fixed and multiplies it by groundspeed (best-glide speed minus headwind component, or plus tailwind) to produce the wind-adjusted range. In other words, wind shifts your track over the ground, not your time in the air. The single biggest lever on real-world range is still flying the exact published best-glide speed: any deviation, fast or slow, reduces the true L/D below the POH figure this calculator assumes.