RC problem

[Guest davfra]

I`ve just had a flight totally ruined by Radar Contact. I was between two waypoints, about a hundred miles apart - I hadn`t missed any waypoints - I was on course and at the right altitude and I hadn`t missed any waypoints. Then I was asked if I was on course as they showed me off it.I`ve heard this problem being put down to long distances. Well this wasn`t the case here. It was a short trip from England to Germany and there were no long stretches between waypoints. They instructed me to fly in the opposite direction.I`ve been using this program for some time now. Everything is ok for a while and then this same old problem occurs and another trip is spoiled.David

[Guest Scott Campbell]

Refly it and when you are at about the place you know this happens, save a dat - before you are busted.Zip up the .dat and related (same named) .flt and .wx files for JD.Also, please post the plan here.

[jd 57]

was there a departure procedure as part of the flight plan? you have to fly much closer to those.did advdisp give you the heading to the next checkpoint you were busted for being off course, or the last one?jd

[ronzie 21]

One thing I've noticed in certain areas is a discrepancy in the flightpath as shown on the GPS (I use Reality-XP's FLA Apollo) and the homing of the VOR. If I follow the CDI on the VOR I show a track deviation on the GPS. Returning to the GPS flight path makes RC happy and I always use it as a backup.At some distance the VOR CDI knob just does not have enough resolution to input a proper course setting and flying the needle can get me 3 or 4 nm off course generating the warning. If I try to home the CDI for direct, it deflects to either side of center. It is not only linear horizontal distance that contributes to accurancy, but slant line distance as well, so if you are high altitude, that error possibility increases.I have enabled the waypoint confirmation ding and keep an eye on the GPS map display at close resolution to insure I am within confirmation limits as I approach each point, especially departure and arrival points.Flightplan generators frequently use their own location databases and since the waypoints in a generated plan are placed by location, it is possible that a navaid location in FS9 differs from the flightplan location as a navaid waypoint entry created by a planner other than FS9. Confusing, right?

[Guest davfra]

I tried the same flight but this time took out the first waypoint after leaving EGKK. Everything worked fine. I can`t believe that was the problem though, because I was a long way from EGKK when I got into trouble.I was interested in the request to check the waypoints on RC when the problem occured. I`m using the Garmin and if the problem occurs again, I`ll chech to see if the Garmin and RC are singing from the same songsheet.After using RC all this time, I think flying without it would take half the enjoyment out of the program. Cheers,David

[jd 57]

there is some fmc on some plane (not sure specifics) that forgets about the first checkpoint. was the fmc flying the plane?jd

[Guest LarsKluver]

Don't ever lock your flight to the line (route) made by e.g. fsnavigator. When using MS atc one does that, to be able to relax a bit, but if you do it using RC, you will find yourself in a problem.Now - this particular issue is familiar, i think. I asked here once and got the answer, but can i remember it. The solution worked and i have never experienced it again.. I think even the flightplan was reversed - looking backwards..Can't remember, but if you're using 3.1 you can ask to be cleared for the next waypoint? Now - the nagging from the controllers works extremely well in RC - there's always something, so maybe one should just close ones ears.. LOL

[ronzie 21]

I do not use FSNAV but I understand it is a module and I assume it controls the A/P.I use an independent flight planner (NAV 3.1). If I lock to that plan loaded in Apollo 50 as I stated RC is happy. I have not tried the default Garmin.So I wonder if specificly it is an FS NAV problem. Have you tried the FS9 planner and the default Garmin for A/P control with RC? That would be the reference system to test RC validity.

[ronzie 21]

Adding:When you are looking at the plan display on the GPS, keep your eye on the bearing to the next waypoint and also on the readout in the advdisp window to see if they agree. Also watch on the GPS the deviation in nm from the desired track. The deviation from a plan route path is hard coded in RC, right? As I remember if you exceed that and do not take corrective action, then you are warned. This in in addition to the heading deviation as set in the RC Control Panel which I think only applies to vectoring.Am I correct, jd?

[Guest Scott Campbell]

Ron,RC doesn't care where the track is, only your deviation from the heading to the next waypoint, which one sets in the options page of RC.What's hard-coded is the distance one has to pass the waypoint. It's 2 miles on DP (30 miles or less from the departure airport), and 5 miles enroute (over 30 miles).FSNav, like most GPS autopilots, follows the shortest path well (accurate Great Circle navigation). But as the distances between waypoints increases, RC isn't as accurate. So yes, the deviation can exceed the setting in RC, and one will be busted.On long flights with a lot of distance between waypoints (about 300 nm or more), I let my CP fly.I haven't read back up. When did FSNav get mentioned anyway? ;-)

[ronzie 21]

FSN was mentioned by Lars in #6 as an example.I'll check again but I'm sure I was within the 15o heading limitation when I was warned and even though I turned more direct to the waypoint as indicated on the GPS display, I continued to get queried as to my course. I was about 1/3 to the next WP, a VOR, on a 150 nm leg at about FL 180. The warning ceased when my deviation from the original plan displayed got under 4 nm based on the ground track (via the GPS deviation reading).Next time I'm on a leg like that, and get the caution, I'll note the advwin heading and the gps heading to see how they agree, not to mention the aircraft heading (and let us not forget, we may be crabbing a few degrees for crosswind component correction but at high cruise speed it should not be that much). Is RC actually looking at the aircraft heading when not being vectored or the ground track obtained heading by your trig master sampling some points.I guess my mind was thinking on distance from the flight path in terms of the allowed deviation when flying published victor or jet routes.

[Guest Scott Campbell]

RC calculates the WCA, yes.It doesn't matter how fast you're going, wind is wind and you can crab quite a lot in a stiff wind. A 150 knot crosswind still pushes you laterally regardless of speed you're going forward.RC calculates and watches your heading and delta to the waypont at all times. When being vectored, it only looks at heading.

[ronzie 21]

Terms:WCA is wind correction angle, correct?delta is lateral deviation from the planned path or section time slice of current ground path (as a geometric vector)? Please explain summarily. I know that the term mathematicly means change. Don't have to give me d(x)= differential calc/trig formula .I understand about the relationship of the crosswind component and forward speed. Still have the heading calculator sitting around (the old slip/scale one) from my VFR days.

[Guest Scott Campbell]

>Terms:>>WCA is wind correction angle, correct?Correct.>delta is lateral deviation from the planned path or section>time slice of current ground path (as a geometric vector)?>Please explain summarily. I know that the term mathematicly>means change. Don't have to give me d(x)= differential>calc/trig formula .Delta is just the heading you fly for the wind correction to stay on course. In effect, it's just Course Heading +/- WCA. As long as you're heading towards the next waypoint, RC is happy.>I understand about the relationship of the crosswind component>and forward speed. Still have the heading calculator sitting>around (the old slip/scale one) from my VFR days.I still have my E6-B sitting in my flight bag. ;-)