Out of curiosity, I just checked for the A380 and the best guess is 15:1, so it does glide better than I expected, but still not that far.
Google tells me that it'd glide ~130 miles if it had a starting altitude of 45,000'. That's better than I expected.
https://en.wikipedia.org/wiki/Gliding_flight#Aircraft_.28.22...
The 747-200 also has a glide ratio of 15:1. I can't tell if that's amazing, good, or average.
A sailplane can have up to 60:1! That's pretty impressive!
According to this: A "clean A320" has 17:1. Neat.
https://aviation.stackexchange.com/questions/14814/could-a-c...
Something I never knew was this:
>As someone said above, you have to remember, pretty well all descents are done with the thrust at idle.
So I imagine the glide ratio is pretty important for all-purposes of flight and not just when engines go out.
A Cessna 172 is worse, for comparison. I believe they are just 9:1. I guess it improves if you stop the prop entirely. I assume it is less drag.
https://en.wikipedia.org/wiki/British_Airways_Flight_9
>Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress.
Quite directly, from ground altitude, a range within which to look for a place to land. As you mentioned the impressive finesse of gliders gives you more room, but gliders won’t generally be flying as high as cruising powered planes.
Combined with speed, a timeframe within which you have to observe, orient, decide and act. Here, both top speed and stall speed give you some hints, and within which there’s a best speed where finesse is optimal. You can imagine how it’s very different between an A320 and a glider, the former for which time runs quickly, you have to decide where to go in as few minutes as possible, the latter for which decision time brought back at a human thinking time scale makes it less stressful but you have to keep cautious of your goal for a longer stretch of time.
Obviously that’s without counting on soaring, which A320s can hardly benefit from (I suppose they can but would largely not move up and certainly not turn since it would would incur too huge drag).
[0]: https://en.m.wikipedia.org/wiki/Finesse_(disambiguation)
That's statute miles (or 111 nautical miles or 205 km). It's quite impressive, really.