Hi,

during planning I noticed, that the MSA ist different for identical but reversed legs.
e.g. BOT NDB to DOMEG shows only MSA 2.200, on the reversed leg (DOMEG => BOT)  it is 2.300. 
For the leg Essen to BOT (2.300) it is even 300 ft less on the reverse leg. Why?

(PC Version 3.6.0.0 & latest Android  Version)



Thanks & Regards
Jan

I just tried reproducing this here and I was unable to. Would you mind posting the saved route here, and letting me know what your settings are under Setup -> Planning Options regarding terrain and obstacle clearance?

Hi Tim, 

I attached the file (pls remove .txt extension).

"Safety Margins" Settings are: 
1.000 / 5,0
1.000 / 5,0

Thanks
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.

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

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.

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..

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

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..

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.