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WAD3

2 problems

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Have Ver 1.3. I entered a flight KSEA-KDEN enroute I had the wind pretty much directly behind me and I was in VNAV LNAV. The track started to follow right of the flight path. after a little bit 200 nm or so I was really off track. So I disconnected LNAV and then placed it back on. I got a message not on intercept heading. I should mention I have not flown much since the Large reinstall of SU-2 (ver 1.2). I had flown many flights with the previous version never having run into this problem. Second problem I have while entering a real world flight plan from FBO web which I have done many times I was trying to put in Jet way to follow and it kept coming up as invalid entry. This again is a problem I never encoutered except if I screwed up a number or something which I checked several times that to make sure I did not.I am not new to the NG as I stated and have read the manual for some reason I am having 2 small problems.Thanks Andrew

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Andrew: For problem 1, all you need to do is turn the plane toward the track and then hit LNAV again. As long as the plane is moving toward your track, you should be fine. If you're flying parellel to it or away from it, that's when you get this error message. For problem 2, all I can think of here is that you are trying to enter the jetway with one of the right-side FMC buttons. The right side is for waypoints; the left side is 'via'. That's where the jetways go. If that's not it, then there may be a problem in your navdata. Are you sure the FMC is seeing the right navdata file? On the initial FMC screen, it reports what version of navdata it's seeing. HTH.

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Thanks for the help.Well as far as prob no 2 I will check that once I land.As for prob 1 I can tell you the LNAV disconnected anf flew me way off course. I have no idea what is going on. This has never happened to me before.Anyone else?Thanks Andrew

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Andrew,For your first problem. What was the distance between your waypoints? There is a known problem in the presentation of the flightpath on the ND. This error gets bigger the further away your waypoints are. It has to do with the ND not taking the great circle into account. My guess is that you were right on course but the flight path drawn was off by some distance due to the above. Can you confirm?Hope it helps,

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I think that might be it. For some reason the flight plane had a waypoint 600 nm (approx) away. It was a Frontier Flight plan. I guess that solves that because I dont think I ever had a way point that far apart before.ThanksAndrew

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Hey Andrew,Problem 1:As I understand it, there are two distinct processes involved here. One plots the path that LNAV will fly, and the other process draws the path on the ND. The first is extremely complicated and it should be considered accurate. The second (what you see) is based on simplified algorithms designed to preserve fps by reducing processor power. You should really only notice this on waypionts that are a long distance apart.If you do notice a discrepancy, I believe that LNAV should be considered correct and the display incorrect. If you are doubting the LNAV then tune in a VOR and monitor raw data.Hope this helps.

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>Hey Andrew,>>Problem 1:>>As I understand it, there are two distinct processes involved>here. One plots the path that LNAV will fly, and the other>process draws the path on the ND. The first is extremely>complicated and it should be considered accurate. The second>(what you see) is based on simplified algorithms designed to>preserve fps by reducing processor power. You should really>only notice this on waypionts that are a long distance apart.>>If you do notice a discrepancy, I believe that LNAV should be>considered correct and the display incorrect. If you are>doubting the LNAV then tune in a VOR and monitor raw data.>>Hope this helps.>>Also, try adjusting the range scale on the EFIS panel up a bit, say to 320 NM, and you should see how your course line on the ND isn't THAT far away.

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Thanks everbody for the help. I think I will do my best to reduce the length between waypoints. I will also trust the LNAV.Abdrew

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