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yahavl

B777 navigation problem

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B777LR LNAV turning prematurely and then tracking wrong course to next WP.(Subject is PSS 777 200 LR version 1.1)Also LNAV fails to fly the pre programmed STAR.Any insight on these matters would be appreciated.Yahav Lipinski.

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Yahav, could you put a screen print here so we can see what the nature of the problem is? Also, did you check your LEGS page to see if there was a route discontinuity? That is usually the problem when I don't check.

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Thanks for the help DanNo discontinuity in the legs page. The 777 simply ignores the STARs waypoints.(LCLK REXAL1 ARR)If I try to force the next waypoint in the CDU the FMC plots a course from an unknown and distant location.As far as the rout tracking is concerned, the PSS 777 LNAV logic seems to create premature direct-to's from WP to WP causing the aircraft to follow a wrong track to the waypoint.This of curse is unacceptable by any navigational standards as this behavior completely Disregards the airway system witch is there to provide terrain clearance, traffic separation and Radio reception.I will try to capture some screen shots during my next flight.Yahav Lipinski

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I think this problem has some thing to do with specific waypoint types in the procedures data file or maybe a compatibility issue between pss777 and the SID/STAR file.(The airports are LLBG & LCLK)The premature turning to next waypoint I think is do to the FMC canceling the airway to the next waypoint and replacing it with "direct" on the rout page itself.This happened wile inserting the SID and RWY in the ARR/DEP page.Also some weird things happen when canceling waypoints or filling in discontinuities wile flying.I Hope there will be a fix for this.If the auto flight system would be as stable and predictable as the manual handlingOf this PSS creation this bird would truly be amazing. (VOR LOC & APP work very smoothly by the way).Some screen shots of these situations have been included on this post!Yahav Lipinski http://forums.avsim.net/user_files/153102.jpghttp://forums.avsim.net/user_files/153103.jpghttp://forums.avsim.net/user_files/153104.jpghttp://forums.avsim.net/user_files/153105.jpghttp://forums.avsim.net/user_files/153106.jpghttp://forums.avsim.net/user_files/153107.jpg

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You're not the only one with the problem. I have had the same problems.On SID's I am starting to go into the legs page and selecting the current waypoint and re-inserting it at the top (the direct to function). This seems to stop the SID route dropping out. It's happened to me every time flying the Dover SID from Heathrow.As for the approach thing where you select direct to the approach fix (CF22 in your example) I again have the same problem. Hoping these will be fixed when the patch comes out. Seems this won't happen before the 757 is released though. Maybe one day we'll have a 777 that works properly!Oh and by the way, PSS are (or should be) aware of the problem. Both problems were brought to their attention a while back.

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Thanks Phil, good to know I am not the only one having these problems.Yahav Lipinski

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