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3 Answers

How would I calculate glide ratio.

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General Aviation

How would I calculate my glide ratio? 

If I am at 8000 feet would I multiply 1.5 by 8 because the ratio is 1.5 per thousand ft?

which would be 12nm 

Also where did a ratio of 9:5 come from? 

i may have the numbers mixed up but I’m just trying to get an understanding on this topic because essentially I’m just trying to figure out how much distance in NM I would have if my engine cuts out at that altitude.

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3 Answers



  1. KDS on Jul 13, 2023

    I suspect that the 9.5 figure you mentioned is what the glide ratio of your aircraft is or what someone told you it is. Given a glide ratio, it is simple math. Whatever altitude AGL you have times the glide ratio is how far the aircraft could go (in feet) before encountering the ground. To convert that to statue miles, nautical miles, kilometers, or grid squares, just divide the result by how many feet are in the unit of measure you want.

    However (and there is always a however) other factors figure in there. Depending on the weight of the aircraft, the airspeed needed to achieve the optimal glide ratio changes. The heavier you are, the higher the airspeed. The wind obviously plays into the equation. If it is an airplane, is the propeller windmilling or stopped changes the glider ratio. Updrafts and downdrafts are going to change things.

    If you really want to immerse yourself in the subject, Google “Glider Flying Handbook online” and take a glance through FAA-H-8083-13A. After all, when the only engine you have quits, you are going to be a glider pilot.

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  2. Mark Kolber on Jul 14, 2023

    The 9.x is the same ratio after converting thec1.5 FPNM to feet. Useful for units whuch cakculate glide rings. Less so for us,

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  3. Mark Kolber on Jul 14, 2023

    I messed up my typing in that one. Let’s try again…

    The 9.x is the same ratio after converting the 1.5 nm to feet. 9,114/1000 = 9.1.

    Useful for units whuch cakculate glide rings. Less so for us,

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