You are welcome to post a thread regarding this change in our Suggestions forum. I believe that we had at least one complaint in the past when we allowed an obstacle that the user deliberately planned to turn before, to greatly influence the MSA of both the before and after leg. I can see how you might want it to, but our behaviour has been consistent for quite a long time now.

Tim,

I would like to discuss again the calculation of the MSA. Please see attached screenshot.
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The MSA for the first route section is given with 800 ft, although the obstacle (568 ft) is almost directly on the track.
I would expect the MSA to read 1.600 ft.

S‌ettings for safety margins are 500 ft / 5 NM (Terrain) and 1.000 ft / 5 NM (Obstacles).

P‌roposal: Virtually extend the track line by xx NMs to include the obstacles within the turn area for MSA calculation.
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R‌egards
Jan

On the contrary, it would be quite desirable! There is no difference between an obstacle being outside of a straight track and outside of a turn. If you set up SD to compute the MSA based on obstacles a certain distance from your track, it doesn't matter if you're on a straight line or in a turn. If anything, it is more critical in the turn since you don't have any course guidance in the turn itself.

If you have a long leg and there is a significant obstacle near one end which affects the whole leg, you can insert intermediate waypoints. Again no difference between turns and straight tracks.

Also, from a regulatory point of view, there is a minimum altitude for night VFR which is based on obstacles a certain distance away. This distance apply equally in turns as it does in when flying in a straight line.

That isn't always a great solution. For example on a long leg, it would typically be quite undesirable to have the entire leg's MSA adjusted for one obstacle that is very much on the outside of a turn at one end. Although I do agree that it's a little unintuitive to have only one leg affected by it.

We can't do anything immediately about this as it's part of a core part of code that we have no plans to touch in the next couple of weeks (we're quite busy). I'm open to suggestions on this thread as to the best way to treat such obstacles, though, so we can address the issue in the best way possible.

Pardon, but I still don't get it..

EDLE -> BOT : MSA 2300
BOT -> EDLE: MSA 2000

There is an obstacle (1218 ft) 1,4 NM northwest of BOT.
Please correct me, but with the margin set to 5 NM /1.000, the MSA should read  2300 in all cases, whatever the turn radius..

You do. It's just that the direction does affect whether the obstacles get included in the calculation for one leg or another.

Generally, are the waypoints handled as fly-by (cut the corner) or fly-over waypoints? I assume fly-over waypoints..

I would assume that the thickness of the route covers the turning ratii already. The planned route directly connects the waypoint (no indication of turns), so I expect to have obstacle clearnce within e.g. 5 NM around the waypoint, no matter from wich direction I approach the waypoint..

We already have the thickness of the route for obstacle avoidance purposes (that's the option you set) so it really just comes down to how you're turning into and out of the leg.

Thanks.

I understand the MSA depends on the turning circle at waypoint.

If you have already the turning radius, would it be an option to create a "turning radius circle" around the waypoint. Then it doesn't matter how you turn into the leg and the MSAs are consistent.

Regards
Jan

Thanks, got it, and I can now see the same thing. I needed to expand my obstacle clearances. It'll be an obstacle. SkyDemon needs to take into account obstacles that are not strictly enroute along a leg of your flight, but which are in the "turning circle" around your waypoints, when it calculates the MSA for that leg. So how you turn into a leg does affect the MSA for that leg, which is why you might get slightly different values for an outward and return leg.

I know this can appear confusing but the alternative, which is to not take account of those obstacles at all, would be dangerous.