777 FMC SID deviation

[philbrown 9]

Heathrow DVR6J (total miles Runway to DVR 71nm). 7nm before DVR magenta line disconnected from aircraft to DVR and aircraft started a left turn. Turn was aborted with quick use of HDG HLD. Thought this issue was resolved?

[Guest Phoenix5]

Phil,What navdata cycle etc, are you using?

[philbrown 9]

0506 (quite an old one - I'm waiting until Navigraph start to release terminal procedures for all my addons before updating).The SID/STAR files are dated early September 06.I'm planning to do some more testing when I get a free moment to try and tie down when it occurs (if it does) on other SID's other than the one I had the problem with.Will post back with results.

[FOD 23]

Phil,As you say, this should have been resolved in the last update - we did not see it in testing.I have just run egll - eddl three times using the DVR6 SID out of the 09 runways and the route stayed solid throughout. I'll now have a look at a couple of the routes that I know had problems. If you see it again, please post the details.RegardsJohn Rooum

[philbrown 9]

OK, just run a couple of tests. Was able to replicate the problem with several DVR SID's off Heathrow.DVR6J off 09R as reported in the first post.Also happened on DVR6K (09L) and DVR4G (27L).All at about 7.5nm from DVR. The aircrafts makes a small 5 degree bank left to fly for KONAN.It problem doesn't arise after a certain number of miles have been flown, or after a certain amount of time with the autopilot engaged, as the 09 SIDs and 27 SIDs have quite a big track mileage difference, and they all occur at exactly the same point.Don't know if this is just a problem with the Heathrow SIDs, or if it is a problem in general with long SID routes.Is it possible that this was actually fixed, and was somehow not included in the base pack? I know the clock night texture problem seemed solved in the downloadable patch, but reappeared in the base downloader?

[FOD 23]

Phil,Not sure now that I know exactly what you see. I assumed that either the magenta line disappeared comletely [never seen before] or that several waypoints disappeared from the CDU for no reason [used to happen during STAR] but the route remained in the FMC/HSI?Is it just that the FMS changes from DVR to KONAN early? I'll have another look.John

[FOD 23]

Phil, Answer "yes". I see it now - looking for something else before.This is not the original problem we had where the FMS dropped several waypoints during a STAR and turned directly towards the runway.I suspect that this might be something to do with the SID transition into the planned route - it only occurs at the point where the SID ends; the previous wp and the subsequent wp are all handled correctly.I need to look at other SID just to confirm it is not unique to DVR.BTW also occurs with earlier releases of the 777 gauge and with the 757.John Rooum

[philbrown 9]

Just flew a BPK aff 09L at Heathrow, and it ran fine. Maybe a little too fine.In the image below, you can see where the magenta line has taken into account the amount of the turn and cut the corner slightly on BPK to easily establish on the airway towards CLN. The aircraft, as the images shows, didn't follow this though, instead flying overhead BPK and then having to make a correction in order to establish on the BPK-CLN track.http://forums.avsim.net/user_files/166367.jpgMaybe there is a small issue on the way the SID connects to the main route. It is only a minor one however.

[FOD 23]

I've just flown 2 SID out of EGPH. Both were ok; indeed one had a turn similar to your example - but that cut the corner correctly to make the next track.OTOH I had an example earlier today in the 757 at the end of a SID as per yours - the aircraft flew 1 - 2 nm past the wp before starting the turn to make the next wp! Strange but I guess the FMS' pilot is no different in the end from real ones and is allowed the odd senior moment!I'll have a look at the SID I fly in the next few days in more detail and see if there is any common thread.regardsJohn