FSX - 737 - PM - Waypoints

[Peter Dowson]

I made some tests, I do not see this problem. LEMG -> EDDS. First section is with no wind / clear. Second is with 25kts almost cross. Tracking appears perfect and no map shift that I can see. Perhaps I miss the point of the problem though? Someone said 'turning in' but the a/c passes over each waypoint perfectly? Please see images, and then please offer a suggestion on how to show me specifically the error so I can recreate. Thank you.

I think you are looking at this in the same way as I did initially -- I never saw it either until I was shown. Then I started noticing it myself. Try exactly the same but

(a) with a much larger scale on the ND. I think with an 80 mile range the angles aren't large enough to notice much.

(b) with many more closer-spaced waypoints -- I seem to recall, when Ray first showed me the problem, he included pretty much all the waypoints enroute, whether reporting ones or not.

Perhaps, if Ray is looking, he will be able to supply a specific example for you to compare with his results. I don't have time before Christmas -- I'll drop a line to Ray.

[LATER]

Ray's given up on FSX, he's gone back to FS9, so he's not really able to demo this at present. But he points out that the original example he supplied PM support, way back when, would show it well. This is an EGCC-EIDW route with in the main cruise part a number of waypoints all in a straight line. The fact that there's no change of heading at eacvh of these serves to exaggerate the "turning in" to the waypoint at the end of each sohrt leg, and the subsequent reversal of direction to head towards the next waypoint.

Do that with the ND range set to 20 or 40 at most to see it there, or just watch out the window as the horizon tips first one way then the other as you cross each waypoint.

Ray's sending me the actual route he uses so I'll post it here.

Best

Pete

[JonathanRichardson]

Hi Pete

Okay, I'll wait. Must be a way to recreate it - I did some further tests just in case but it did not show up.

Regards
Jonathan Richardson
Project Magenta

[Tony]

Hi all,

This problem/bug ( I called it "swirling" at the time) exist since the early days (not only in FSX).

http://www.mycockpit.org/forums/show...t=tony&page=40

Hope Jonathan will be able to acknowledge and have it fixed.

Regards
Tony

[Peter Dowson]

Okay, I'll wait. Must be a way to recreate it - I did some further tests just in case but it did not show up.

Ray uses this test flight (save it as a .PLN file). Once past WAL the aircraft should not deviate from a straight line as it passes each waypoint, yet it does a series of sweeping S curves!

Pete

================================>>

[flightplan]
AppVersion=9.1.40901
title=EGCC Manchester to EIDW Dublin
description=EGCC, EIDW
type=IFR
routetype=2
cruising_altitude=18000
departure_id=EGCC, N53* 21.23', W2* 16.50', +000257.00
departure_position=1
destination_id=EIDW, N53* 25.28', W6* 16.20', +000242.00
departure_name=Manchester
destination_name=Dublin
waypoint.0=, EGCC, , EGCC, A, N53* 21.23', W2* 16.50', +000257.00,
waypoint.1=EGTT, WAL, , WAL, V, N53* 23.52', W3* 8.07', +000000.00,
waypoint.2=EGTT, MALUD, , MALUD, I, N53* 24.80', W3* 36.50', +000000.00, L975
waypoint.3=EGTT, ROLEX, , ROLEX, I, N53* 25.70', W3* 58.07', +000000.00, L975
waypoint.4=EGTT, LYNAS, , LYNAS, I, N53* 26.55', W4* 20.00', +000000.00, L975
waypoint.5=EGTT, NATKO, , NATKO, I, N53* 27.20', W4* 38.12', +000000.00, L975
waypoint.6=EGTT, DUB41, , DUB41, I, N53* 28.23', W5* 9.85', +000000.00, L975
waypoint.7=EGTT, LIFFY, , LIFFY, I, N53* 28.80', W5* 30.00', +000000.00, L975
waypoint.8=, EIDW, , EIDW, A, N53* 25.28', W6* 16.20', +000242.00,

[JonathanRichardson]

Hi

I can certainly try the plan, but I never saw anything like swirling like describe - it might be something else (possibly). I thought the main issue was only in FSX, a slight offset from the route due to Mag var and that has (is supposed to be) fixed. I certainly can not recreate it in FSX. Not to say it is not still there for some reason - I do not doubt it - would like to see it though...

The only deviation I notice and know about is a slight delay phase at high speed cruise as the CDU switches to the next waypoint depending on angle / steepness of turn (see images) this could be improved upon, but I don't think it should be of any big concern. If it is happening on systems at low speed / low altitude perhaps it points to slow update times of the specific system. Not sure about that.

Regards
Jonathan Richardson
Project Magenta

[abril]

Jonathan prove with "TRACK MAGNETIC"magnetic in the ND.
In any place of Spain it happens that before arriving at wpt the airplane tries correct course towards that wpt, and it flies over as soon as it, corrects its trajectory until taking the new course towards next wpt, but that yes, when TRACK MAGNETIC is put in the ND. The mode with which you are flying not I have tried it.
Greetings

Israel Abril Fernandez

[Ray Proudfoot]

Hi

I can certainly try the plan, but I never saw anything like swirling like describe - it might be something else (possibly). I thought the main issue was only in FSX, a slight offset from the route due to Mag var and that has (is supposed to be) fixed. I certainly can not recreate it in FSX. Not to say it is not still there for some reason - I do not doubt it - would like to see it though...

Hi Jonathan,

If you can find the time to fly EGCC-EIDW that route always demonstrated the problem very clearly to me. You don't even need to fly the whole route. By the time you reach DUB41 the problem should be very evident.

As Pete said earlier I gave up on FSX and reverted to FS9 and I never see this issue in that sim so it's definitely a FSX-related issue. I will try to find some time over Christmas to test the latest builds in FSX with this route. I'm not up to date because the versions I have don't give me any problems in FS9.

The only deviation I notice and know about is a slight delay phase at high speed cruise as the CDU switches to the next waypoint depending on angle / steepness of turn (see images) this could be improved upon, but I don't think it should be of any big concern. If it is happening on systems at low speed / low altitude perhaps it points to slow update times of the specific system. Not sure about that.

Regards
Jonathan Richardson
Project Magenta

I see this occasionally but I can eradicate it by editing my plans to remove waypoints that are too close to a previous one where a large heading change is required.

The turning-in problem is quite different and seems more noticeable on a straight-line route with multiple waypoints < 20 miles apart.

Cheers.

[JonathanRichardson]

Hi

You think flying in MAG or TRUE makes a difference to this? I do not see that. I tried both.

Regards
Jonathan Richardson
Project Magenta

[abril]

Jonatan, not HDG MAG or HDG TRUE, prove wiht TRACK MAGNETIC mode in the ND.
Sorry, my English is very bad.

Israel Abril Fernández.

[Ray Proudfoot]

Hi

You think flying in MAG or TRUE makes a difference to this? I do not see that. I tried both.

Regards
Jonathan Richardson
Project Magenta

Hi Jonathan,

I doubt it. My settings in the PM software are no different for FSX than they are for FS9 so I don't see how that could be a factor.

Are you saying you've now tried this test route and were unable to reproduce the problem?