LNAV calulates loop

[DoubleWhisky]

IXEG 1.3.

Procedure I flew:

EPKK ARR RWY 25 - BAREX2G + ILS25 via KK502 trans.

I shortcut downwind and final (as real) from KK506 to VAXOB. Result are like in screenshots below:

 

 

 

I didn't interrupt LNAV mode to see what happens:

 

 

Cheers!

[Litjan]

Yeah, that looks odd. Maybe it is JUST about missing that waypoint so it is turning back to make it? Try to put in a speed of 160 kts for VAXOB and see if that helps?

Cheers, Jan

 

[DoubleWhisky]

Speed change helps a little speed. Nevertheless it's not supposed to happen:

 

160 kt

150/140 fixes the problem.

And then back to 170 for example:

 

Trying some values and then setting it to 150:

 

 

It's difficult to find out what's wrong exactly.

 

But you can easily test it even without flying. This bug can be reproduced easily at any time.

Important: I did if GW around 53 tons. It's important.

Edited May 31, 2020 by DoubleWhisky

[tkyler]

What dataset is this?  Aerosoft or Navigraph. and what cycle?     Agree the loop shouldn't be there; however, it is probably a bypass situation, which the FMS is supposed to handle, indeed ours is normally very good about it.   Those two waypoints are probably too close together to make KK371 at 170 knots when you shortcut to 'VAXOB', so lowering the speed is quite appropriate since you altered the published procedure. If you shortcut at KK501, you probably won't see the issue.  Procedures are generally designed so that they can be flown without bypassed waypoints, so when you modify them, it is possible to get unexpected results (but not a circle...the FMS should bypass KK371.  

-tkyler

Edited May 31, 2020 by tkyler

[DoubleWhisky]

Navigraph 2006.

[tkyler]

3 hours ago, DoubleWhisky said:

It's difficult to find out what's wrong exactly.

 

this is FYI only, in case you're curious.....without a doubt, the speed is too great (bigger turn radius, earlier turn point, later rollout point)  to finish the turn before passing KK371, but probably just barely.....and I suspect that our bypass code isn't being run since the next waypoint is a runway,  which is a bit of a special case waypoint.  I will revisit our bypass code to check it out and under what conditions it runs, but it does need to run and would fix this issue.

-tkyler

Edited May 31, 2020 by tkyler

[novato X11]

 .....    First of all, thanks for the update. I really like this classic model of aircraft ... in relation to the report above, it is also the same problem on another route and I am using navigraph , attach the flight log that shows this problem, I hope it helps to clarify something about what happened ..  

GizmoLog.txt

IXEG_FMS_debug.txt

plane.txt

 

Log.txt

Edited May 31, 2020 by novato X11