Method to deal with "Off Course" comments

[Guest lou ross]

Long distances between waypoints provokes these messages- I think it could be due to MS straight-line nav vs. great circle, but I could be way off on that one. Anyway, when the controller tells me I'm off route, the easiest way I've found is to request deviations due to wx. The other suggestion was to add many short distance waypoints, but that's a lot of work. Deviations for wx allows long distance flights. Any comments? lr.

[ronzie 21]

I started having that problem when using high-altitude airways. If I used long-range VORs, I would get that error. If I monitored via GPS, I noted the difference and if I followed the flight plan on the GPS correcting to the displayed track, I did not generate those warnings.It seems there is a coarse rounding error when attempting to change the courseetting on VOR CDI displays in that you get quite a deflection step for a one degree change if you are quite some distance away attempting to home on a VOR and/or using your flight plan radials. It does not take too much of an off course deviation VOR CDI indication to go beyond acceptable limits when the VORs are widely spaced as in the high altitude routes.I believe buried in the RC manual is a statement regarding GC deviation vs direct paths when flight planning causing errors on long legs.

[Guest lou ross]

Understand what you're saying. I'm using the FMC routing in PIC767. I'll look thru the RC manual, I could have missed that info. lr.

[jd 57]

i had put in a great circle route calculation when i started 3.1 work. but it broke something else (i can't remember what it was), so i took it out, and reverted to the old code.sorry. many intersections between distant points is the way to go, at the moment. i'll make a note to fix it for good in 4.0.jd

[ronzie 21]

So, what does your navigation trigonometry tell us is the max leg between navigation points before we get those off course errors.

[jd 57]

i've had my fill of trig, with the conflict detection routine. actually my good friend john burgess did the trig, i just coded it.my guess is you could get by with 120-150 mile legs.just a swagjd

[Dean_EGTC 57]

Actually you can get away with 300ml legs as long as you're not too far north or south of course.