"Sir?""I hope you don't drive like this".At last, Flight Simming with a sense of humour!Actually it would have been funny had ATC not been telling me I was ("This is the third time.....") way off course, when the loaded Flightplan in FSNav and the ATR EHSI - which of course is the plan loaded into RC4 - was showing that I was spot-on. ATC wanted me to turn a 180 and go back where I came from, halfway through the trip and 70 ks from my destination.Any explanation would be appreciated.

You probably missed a waypoint somewhere, or else they got out of order on your flight plan for some reason. Maybe?

Yep, drdickie is absolutely right. You missed a checkpoint (waypoint) - the big clue is the 180 degree turn RC wants you to do to reach it. You're required to pass within 2nm in the departure phase and within 5nm in the en-route phase to be credited with a checkpoint.To confirm this is what has happened, compare the waypoint RC thinks is next (you'll find this at the top of the advdisp display) with what your FMC, GPS or whatever you're using for navigation thinks is next. If they're different, you've got a problem. The solution is to select the "Dir Chkpoint" item from the advdisp menu (you'll find it on page 2 by pressing the "next" key) and request a direct route to whichever waypoint your FMC/GPS etc. thinks is next. Problem solved.Pete

That makes a lot of sense. Of course, (he says innocently) I don't recall missing a waypoint. Actually I missed a whole bunch of them immediately on take-off: the F1 ATR is such a doll to handfly I simply forgot to put her in LNAV! I was back on course soon after and ATC was cool until much later. Anyway, it's all good experience.Thanks for the replies.