I think i downloaded your Pan Am flightplan Chris, and AIFP cough out a lot of errors regarding flight durations that goes for too long, leading to "flights unable to return in period errors". If you're willing to look at it will you make some fixes? I realize its an old flightplan that you posted years ago.
I also find a 707 flying from JFK to Bangkok, Guam directly. Is this accurate? As far as i know a 707-320 can't fly that far with the cargo and passengers they put back then
Ok. First the good news: As you suspected, I did the flightplans for Pan American, 1971. The bad news is that I don't have the source files anymore, although I still have the timetable. I can confirm that there was no direct flight from JFK to Bangkok. What you're seeing is probably a repositioning flight. One thing to consider when looking at timetables - and especially old ones is that they do not contain all flights: excluded are cargo, charter and training flights (and that's excluding actual errors by the airline or OAG). When that data, even perfectly copied, is run through MRAIC, two things will happen. First, the flights won't balance (necessiting positioning flights which probably won't reflect actual aircraft performance) and second, even though you've balanced everything, MRAIC will generate "orphans" in the output file, such as "NFFN - YSSY AC#,QFB3F,1%,WEEK,IFR,6/20:35,@0/00:50,320,F,0581,YSSY". More positioning is needed to fix that. I tend to err on the side of having more flights around, even though they may accurately depict reality. If that inconveniences you or others, please accept my apologies and feel free to cut up, fold, spindle or otherwise mutilate my flightplans
Exit runway when able
btw, "YRGN" is actually Rangoon, but only in the Pan Am '71 flightplans