Occasionally, when I start up the -700 I find that my magnetic compass and ND headings are both showing incorrect values. They will both indicate the same heading but it is off by about 130 degrees (i.e. I am facing 340 but the indicators show 210). This affects the LNAV function and makes navigation just a tad difficult.It does not happen at every airport and I have thus far only seen it operating at somer airports in the USA Northwest.

Please sign your full name in this forum.The mag var is greater in the NW than elsewhere in the contigious US, but not that much. Try turning off add-on sceneries and look for a difference.

Please sign your full name in this forum.The mag var is greater in the NW than elsewhere in the contigious US, but not that much. Try turning off add-on sceneries and look for a difference.

This does not appear to be a mag variation problem. I also just tried a flight in the USA southeast and the effect was the same. What I suspect is that it may be related to the fact that last night I d/l a SID/STAR cycle. This may be screwing me up now and of course, I neglected to save the old file as a backup so now I am not quite sure how to unravel that mess.Roger Curtiss

It's not possible for the navdata files to corrupt the headings, these are just text files read only by the pmdg FMS.Hope this helps: http://ops.precisionmanuals.com/wiki/How_t...Tracking_Errors

Thanks Dan. And also, just to clarify, I was experiencing this problem before I did the SID/STAR d/l...just not on the east coast. I will try disabling some scenery and see if that makes a difference.Roger Curtiss

I did the old tried and true shutdown FS and restart it. Sure enough, when I did that and repositioned the airplane at KSEA the compass/ND headings were working just fine. So it is an intermitent thing and I suppose I can live with that...until 737NGX arrives!Roger Curtiss