iFly GPS Forum

When we fly i'm sure everyone here at sometime, perhaps frequently, look out the window at some less intimidating clearing (or in the mountains here ..... "survivable looking piece of maybe-flat valley down there") and making a gut-estimate about whether it's within glide distance.

So here's the idea:
My aircraft has a nominal glide ratio of 10:1 . Assuming I can't make a perfect visual calculation (a safe assumption) about how far that is I'd prefer to always be estimating conservatively.
So I'd like in iFly setup (aircraft profile) to be able to enter 8:1 for my glide ration.

Since iFly knows my AGL if flying over moderatly flat terrain it should be able to calculate and show a circular radius on the sectional that's my 8:1 reachable glide radius.
That would be very useful, as at a glance I could see that trying to glide to that dry lake would be out of the question. Or a peice of cake.
If it's willing to do a bit more complex calculation:
It knows the altitude of all the terrain within my flat terrain glide circle, and can adjust that perimeter based on that.
For example, if aft of me the terrain is dropping off and increasing (even subtly) in front of me rather than showing a circle it could be drawing an oval extending further aft than forward. irregular shapes would occur in terrain with varied ground altitudes within the nominal glide range.

Yeah, I know that the wind (which currently iFly doesn't calculate) also distorts the glideable-to-ground patch.
But even having the simplest case circle (no wind, flat terrain below) on display would be useful in routine flying for that "wonder if I can reach that" question, to say nothing of it's use in decision in a true engine failure.

You said only one suggestion per thread, so I'm going to suggest an actual glide ratio readout instrument in an other thread.

Alex

Hmm. You know, if iFly has some internal idea of the wind, iit could take that and terrain into consideration in the calculation. The result probably wouldn't be a circle, but it would show the airports within gliding distance, or, failing that, the best terrain for a forced landing within gliding distance.

In order to use the wind, the'll need not just your gliding ratio but also your best gliding speed.

Furthermore, the wind changes with altitude, which makes things a bit harder to calculate for them.