DC10 polar flights 1980s
I had the "honour" of doing our first flight over the pole.
it would have been in the extended range version as fuel was tight and we often planned Fairbanks with technical onroute diversion to our destination of Anchorage.
Dispatch was excited and the over the top route was only a couple of minutes longer than minimum time.
The INS took 12 minutes to initialize including loading the route from a betamax size cassette.
I do not remember any lattitude restriction wrt initialization.
Above 65? we had to go to polar navigation which split the two fms displays, the computers worked on individually calculated position rather than median and we were not allowed to take out the nav mode on the autopilot.
All went well until we crossed the pole with my display showing a normal indication to the next waypoint (328?nm) whilst the captains showed a track which deviated approximately 30 degrees.
I tried "direct to" on both key pads but was still left with a large track split. Fortunately we had been watching a large moon in the night sky so we had some sort of heading reference.
I checked the triple lat long displays which all were fairly similar and decided with the skipper and engineers blessing that I would ignore SOP, take out nav and manually intercept the meridian. When we reached the next waypoint everything went back to normal.
I wrote it up very clearly but a month later I got a huge bollxxking for ignoring SOP which would be entered on my file.
This was not entirely unexpected as far to many mangement pilots in all of my three legacy carriers didnt have the where with all of line pilots, the exception being technical and base trainer pilots.
A month later I was rostered to assist on a sim check which was being carried out by the chief technical pilot whom I didnt know but I thought that it was a serious problem that should be properly investigated.
It was and I recieved a note that Douglas had discovered a programming error which had been rectified.
Last edited by blind pew; 10th May 2019 at 08:06.