Glide Ratio Calculator
Airborne for the same time. Only the ground moves.
Airborne for the same time. Only the ground moves. Glide distance from height, with the wind correction applied and the height needed to reach a chosen field.
Glide range over the ground
4.44 nm
4.44 nm in still air · 4 min airborne
A headwind cuts glide range badly, and the reason catches people out: the aircraft is airborne for exactly the same time either way, so the only thing that changes is how much ground passes underneath. A 20 kt headwind on a 70 kt glide costs nearly 30% of range. Reachable area goes with the square of range, so anything that improves the glide improves the options disproportionately. Turning downwind on an engine failure buys far more ground than the still-air figure suggests. Book glide ratios assume the propeller stopped, the aircraft clean and the speed exactly right. A windmilling propeller costs a substantial fraction of the ratio, and flying 10 kt off best glide costs more than most people expect.
How the Glide Ratio Calculator works
Glide distance from height, with the wind correction applied and the height needed to reach a chosen field. A headwind cuts range badly, and the reason catches people out.
Also known as: how far can i glide from 3000 feet · engine failure glide distance · glide range into wind · can i reach that field
Where to go next
The Glide Ratio question rarely arrives on its own. These are the ones that usually come with it:
- Density Altitude Calculator — The aircraft flies the air it is in, not the altimeter.
- True Airspeed Calculator — The 2% rule is a linearisation, and it drifts.
- Aircraft Fuel Calculator — Reserve fuel is not fuel you have.
- Speed Distance Time Calculator — Any one of the three from the other two, in four units.
Frequently asked questions
How far can an aircraft glide?
Glide ratio times height. A 9:1 glide from 3,000 ft AGL covers about 1.5 nm in still air — considerably less into wind.
Why does a headwind cut glide range so much?
Because the aircraft is airborne for exactly the same time either way. Only the ground moving underneath changes, so a 20 kt headwind on a 70 kt glide costs nearly 30% of range.
Should I turn downwind after an engine failure?
It buys considerably more ground than the still-air figure suggests, and reachable area grows with the square of range. Whether it is the right decision depends entirely on what is under you.
Does a windmilling propeller matter?
A great deal. It costs a substantial fraction of the book glide ratio, which assumes the propeller stopped and the aircraft clean.
How precise does best glide speed need to be?
More than people expect. Flying 10 kt off best glide costs noticeable range, and the penalty is worse for flying too slow than too fast.
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Related calculators
Density Altitude Calculator
The aircraft flies the air it is in, not the altimeter.
OpenTrue Airspeed Calculator
The 2% rule is a linearisation, and it drifts.
OpenAircraft Fuel Calculator
Reserve fuel is not fuel you have.
OpenSpeed Distance Time Calculator
Any one of the three from the other two, in four units.
Open