How to calculate and understand glide distance?

How would I calculate my glide distance?

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

Which would be 12 NM

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.

• Your math is correct, but I don’t think your glide ratio is - that’s a horrible ratio for any training aircraft. (Where did 9:5 come from? How should we know, you typed it, where did you get it from?!) Anyway, what are you flying? You will get some helpful and accurate answers if you provide a little more detail. P.S. I’m editing your question because you are not asking how to calculate the ratio. Jul 13, 2023 at 14:17
• Not only where 9:5 comes from, but where 1.5 comes from. The space shuttle was 4.5:1 when landing, which is basically a brick. Jul 13, 2023 at 16:03
• 1.5 nautical miles per 1000 feet is a glide ratio of 9.1:1, which is not far off from a typical trainer aircraft (a C152 is 9.7:1, for instance). Jul 13, 2023 at 16:04
• Chris- aha. I read it as 1500ft per 1000ft. Maybe that 9.1:1 shows they meant 9.5:1, not 9:5. Jul 13, 2023 at 16:19
• @TypeIA Certainly you may lose some altitude from the startle factor. But you would have to fail the airspeed control pretty dramatically to lose 33% of your glide distance after that. Having too big a fudge factor is also a problem- it might convince you to ignore an airport or nice field that is in fact in easy glide distance in favor of a less suitable landing spot. Jul 13, 2023 at 18:24