Im having real trouble completing a transatlantic flight.
I fly airliners. Payware with fully functional FMC's. I know how to programme a route and when I fly from London to any destination in Europe or middle east I get there with no problems.
However, when I go for a transatlantic flight things just seem to go wrong. Today for instance In my captain Sim 767 I programmed a route to Canada from London. Things went well until just past Greenland. I did a step climb to 37,000 feet, soon after my auto pilot just did not seem to function. The command button was lit indicating it was working but the plane seemed limp and just went into a Right turn. I hand flew the plane back on track and all seemed fine, but as soon as I engaged the auto pilot the same thing happened.
Previously when I have flown these routes something normaly goes wrong. Once my altimeter said I was at 35,000 but I could see the sea just below me, it seemed I was only 5000ft. I normally set my route and leave it going, when I return more often than not the plane has somehow managed to fly of course and I dont know why. It always seems to just past Greenland. If I do a long haul the other way, say China, it all seems to work ok.
Any hints or tutorials I can follow, or am I doing something completely wrong. Does the plane need to be set up in a special way.