I have a situation that repeats itself every flight. When I input a flightplan into the FMC (using current AIRAC from Navigraph) and takeoff the aircraft follows a "curved" flightpath to get from waypoint to waypoint in my flightplan legs. I've searched the forums and found several references to a flight path deviation, but none of them mentioned this "curved" flightpath between waypoints. The aircraft gradually drifts left of the flightpath (sometimes up to 7 miles left of planned path). The farther the distance between the waypoints the more distance in the left drift. Last night on VATSIM ATC directed me to turn right to 230 so I disengaged the LNAV and selected HDG and set it at 230 degrees. He soon informed me I was flying a heading of 215 degrees. In order to fly the headings ATC wanted I had to add 10 to 15 degrees to whatever heading he issued to me. I've been flying the aircraft for over 2 years now and this has only recently surfaced. It used to be infrequent, but nows occurs every flight. Tonight I started out with ASE, but turned it off midway enroute (a fellow pilot said he "heard" ASE was the culprit...but another said FSUIPC was) and used VATSIM weather. I refreshed and disconnected, then reconnected but no change in the deviation. The aircraft always overflies the waypoint (including the TOC, TOD, and any speed restrictions indicated on the flightpath, but after crossing immediately starts drifting left again. The nose of the aircraft seems to be pointing to the right of the intended flightpath as if I am "crabbing" through the air. I do have add-on scenery installed, but this happens from both default airports and add-ons. I have the latest free mag-dec adjustment downloaded from AVSIM library and always use the latest AIRAC from Navigraph. Other particulars: FS9.1Windows XP SP3Active Sky Evolution Installed and, usually, used.FSInn 1.3 for online flightsPMDG B737-600/700/800/900 (series makes no difference) These are not "violent" changes in direction due to wind shear or sudden wind changes. This is a gradual left deviation from the flightpath with the aircraft nose always pointing to the right of the flightpath. The aircraft follows a parabolo with the waypoints being the ends of the parabolic arc. The process starts all over once I pass overhead of my next waypoint. Any help would be appreciated. Randy "Ramjett53" Tyndall

Visit http://www.flight1.com/view.asp?page=library and download the FSX/FS9 Registry Path Repair Tool by Flight1. If the path to FS9 in the registry is wrong or missing, the addon won't be able to read the magnetic declination file and weird things happen to the navigation systems. Hope this helps, DZ

Thanks for the reply...I will try that. In the meantime I just completed 2 short flights from Boise to Twin Falls and return. BOI to TWF I did in the Level D B767 using the FMC on a flightplan of BOI2.BOI BYI and autolanded on Runway 25 with absolutely no deviation or problems. I did this flight offline and with default weather...no ASE. Flawless. I did the return to BOI in the PMDG 747 on the FMC Flightplan SNAKO1.SNAKO ALKAL CANEK RNAV 28R. Fiasco from the get go. Again, Offline, default weather, no ASE. [/img] [/img] You can see the heading deviation while enroute to Boise in the first shot. In the second you can see that for Runway 28R at BOI I am lined up perfectly...so to speak...and yet my heading indicator says 292 degrees. The Runway heading at BOI is 280 degrees. I am at a loss to understand why one aircraft, the level D, flies as programmed but none of my PMDG's do. Tomorrow I will try with the Wilco Airbus and FMC, apply your fix after that test and then try another PMDG. Thanks again, Randy

Apply the registry fix now and save yourself some time!The reason all PMDG aircraft suffer the problem is because they are coded similarly. Level-D do it differently hence why you don't see the problem there.Best regards,Robin.Apply the registry fix now and save yourself some time!The reason all PMDG aircraft suffer the problem is because they are coded similarly. Level-D do it differently hence why you don't see the problem there.Best regards,Robin.

Hi, your error results out of a corrupted AFCAD File (maybe an old one from FS 2002). Disable all add on sceneries and reenable them step by step to find the one that causes the error. Another solution (not tried by myself) could be putting the magdec.bgl file in a seperate folder and move it on top of the scenery library. Jan-Paul

Ya know what, Jan-Paul? I never would have believed a scenery add-on could have that affect on the navigation within FS9, especially when the Level D 767 flies with no deviations at all. I tried the FS9 Registry Fix...no luck, nothing changed. I tried moving the magdec.bgl update from 2005 (for FS9) to the top of the add-on scenery list...no joy, FS9 would not even load without the magdec.bgl file in the Scenery/Base/Scenery folder. Both of these would have been quick and easy solutions. They may work for others, but not for me. Sooooo.......I disabled all 397 scenery add-ons and fired up FS9...Perfect. As I type this reply I'm flying the PMDG B737-700 from Boise to Twin Falls with a 0.02nm deviation from the intended flightpath and the heading is deadon what the FMC says it should be. No arc or parabolic flightpath. Now for the daunting...and I do mean daunting...task of finding the corrupt scenery file and seeing how to fix it. It's probably one of my hard-earned payware add-ons and I'll have to really think about enabling it again once I find it. Many thanks to all who replied with tips and help and especially to Jan-Paul. Wow...I never would have guessed a scenery could be so "aircraft" selective. Randy

RandyHave you aligned the IRS recently to see if this reduces any drift. It may or may not help whilst you search for above. When I first used PMDG aircraft I had no idea that they modelled this & my aircraft would drift & like you I had to use heading adjustment to get it back on course only to find it would drift again. This may not have anything to do with your issue & you may be an advanced user so forgive me if that's the case but I would be interested to know if it has any affect. Good luck.

I have a situation that repeats itself every flight. When I input a flightplan into the FMC (using current AIRAC from Navigraph) and takeoff the aircraft follows a "curved" flightpath to get from waypoint to waypoint in my flightplan legs. I've searched the forums and found several references to a flight path deviation, but none of them mentioned this "curved" flightpath between waypoints. The aircraft gradually drifts left of the flightpath (sometimes up to 7 miles left of planned path). The farther the distance between the waypoints the more distance in the left drift. Last night on VATSIM ATC directed me to turn right to 230 so I disengaged the LNAV and selected HDG and set it at 230 degrees. He soon informed me I was flying a heading of 215 degrees. In order to fly the headings ATC wanted I had to add 10 to 15 degrees to whatever heading he issued to me. I've been flying the aircraft for over 2 years now and this has only recently surfaced. It used to be infrequent, but nows occurs every flight. Tonight I started out with ASE, but turned it off midway enroute (a fellow pilot said he "heard" ASE was the culprit...but another said FSUIPC was) and used VATSIM weather. I refreshed and disconnected, then reconnected but no change in the deviation. The aircraft always overflies the waypoint (including the TOC, TOD, and any speed restrictions indicated on the flightpath, but after crossing immediately starts drifting left again. The nose of the aircraft seems to be pointing to the right of the intended flightpath as if I am "crabbing" through the air. I do have add-on scenery installed, but this happens from both default airports and add-ons. I have the latest free mag-dec adjustment downloaded from AVSIM library and always use the latest AIRAC from Navigraph. Other particulars: FS9.1Windows XP SP3Active Sky Evolution Installed and, usually, used.FSInn 1.3 for online flightsPMDG B737-600/700/800/900 (series makes no difference) These are not "violent" changes in direction due to wind shear or sudden wind changes. This is a gradual left deviation from the flightpath with the aircraft nose always pointing to the right of the flightpath. The aircraft follows a parabolo with the waypoints being the ends of the parabolic arc. The process starts all over once I pass overhead of my next waypoint. Any help would be appreciated. Randy "Ramjett53" Tyndall

Ever considered upgrading from the stone age operating system and FS9 ?

Ever considered upgrading from the stone age operating system and FS9 ?

Nope, not even once...ever considered making positive contributions to requests for help and assistance? Randy