Excuse if this has been on a zillion times. I had not noticed it. I have discovered (In FS9, Century of Flight) that when crossing a VOR on autopilot, in NAV mode, in the Cessna 172, Cessna 182, Learjet, 777, and some others the aircraft will go into a steep banked turn, and if you don't recover manually or with the Heading mode, you lose the aircraft due to overstress or crash and so on. The 172 just orbits the station likes it is in love. The Mooney will fly on across but it drops the NAV mode. The NAV light goes out and the airplane flies on. Is this a Microsoft problem? Are they going to fix it? What are the experiences on Avsim about this problem?ThanksAeromachines

That's because in FS and the real world when you're passing over the VOR you will lose the signal. The autopilot doesn't know this, and it thinks it's off course.When I did my IFR training it was called the "cone of confusion." I don't know if they still call it that. The area gets larger the higher you are. As you get close to the station, it gets more sensitive. In a real plane as you start getting into this "cone" the needle starts dancing around, jumping from left to right, and then you lose the station. When it picks it up on the other side, it does the dance again, then goes back to normal.To avoid this, you need to turn the autopilot's nav mode off when you get close to the station. If your plane has DME, when you get to about 2 miles or so, put the heading bug on your current heading and switch to heading hold. If you don't have DME and you are using paper charts, you can use the nav2 to check your position along the airway. Or you can do what I do, and just fly the plane instead of letting the autopilot do it.

Ahhh, I always wanted to ask this to. Out of necessity I've been switching to heading mode as I approach VOR's. I guess it's kind of obvious, but somehow I overlooked the specifics of this procedure in any instructions I've read about tracking VOR's.DannyCYVR

Good answer, perfect explanation about the real world. But how do you know this about what the autopilot thinks? (I know, you mean senses electronically). As a pilot I didn't go into what was so obvious to me. But I did send out a similiar explanation to my younger brother in New Jersy. And, yep, it is the "Cone of Silence," and I had not thought of that phrase or title for some time (like some ten or twenty years maybe). Well I see I 've changed it, you said, "...confusion." To me it was "Cone of Silence." As you flew, or fly now, my technique was similiar. I used the heading mode most of the time and the NAV mode little in real life when tracking VORs. But if I was in NAV mode, I would take the altitude, and add to it one or two DME miles depending on ground speed. For instance: If I was at 7,500 feet say, in the Cessna 182, I would turn the NAV mode off at 1.5 DME for altitude, plus 1.0 for slow ground speed. Therefoe, at 2.5 DME off goes NAV mode, and on goes HDG mode. Do the opposite just after station passage. I have to admit for the last several years of my flying I was on a Collins RNAV and did not have this problem. But seems as when I flew across a VOR in an older piece of equipment, or while using NAV mode, most of the time the aircraft rocked a bit left, then a bit right, then (unless my ground speed was something horrendous) the Nav mode would bite in again and on we would go. But, that was a long time ago. And see, look at me, in my first request, I was being selfish. I only wanted the answer for me and your explanation worked great for a lot of other pilots. So thanks, and I still think Microsoft can fix this. The airplane ought to fly on even if it waggles its wings a bunch. It ought not to go into a graveyard spiral just because the pilot is getting a tad of shuteye right at that moment.

I could be wrong here but I don't think that MS models the cone of ???. I believe what you will find is that when this happens in MSFS, you are flying in a crosswind. The autopilot lets the aircraft drift well off the VOR radial until it gets very near the station, then (at the last minute) it has to crank in quite a bit of turn to get close to the station. R-

I have always called it the "position of ambiguity" -lol!However-I do believe fs models it. Place your aircraft on the ground via the map next to a vor. Taxi right over it and note what happens. (No crosswind on the ground). In the air-you will also get the momentary off flag when directly over the vor. A further confirmation would be if the autopilot goes screwy at the moment the off flag occurs.Lowell-I will check what my autopilot does the next time I fly. I have to confess-I like you have used mostly the hdg mode when I use my real autopilot and will be interested to see what it does in nav mode when crossing...I would suspect that make and model of autopilot might make a difference in reaction?http://mywebpages.comcast.net/geofa/pages/Geofdog2.jpg

Hello All:I too am aware of the cone of silence above a VOR station. I have experienced the same autopilot problem as outlined when flying FS9. I wonder if anyone can recall if the problem existed in earlier versions of MSFS or any of the other simulators on the market. In real life IF the same condition was experienced as is experienced with FS9 flying across the "cone of silence" this phenomenon would be know as the "cone of death" and there would be placards, NOTAMS, cautions, map legends, and detailed emergency instrument training required to coordinate autopilot/VOR navigation. The higher altitude, of course, expands the width of the "cone of silence". However the ground speed of the aircraft crossing the VOR would limit the effect of the "cone of silence". The fact that a Lear Jet used in FS9 immediately enters a "fatal" spiral indicates this problem is not something to be taken lightly. IF!!! this is real life, God help us. I think it is only a FS9 problem. I wonder how many more FS9'ers or previous MSFS pilots experienced the problem?And to my brother Lowell..."Surely you would not take 'a little nap'! Ha, ha.IAmRonWileyCommercial ASMELCFIBGI - AeronauticsFS9 Pilot

Only a couple of planes I've flown had an autopilot. One didn't work at all, the other was kind of weird. In heading hold mode, it would hold 10

When I'm flying in NAV mode I've always gone to HDG as I'm approaching the VOR until the off flag appears, then change to the frequency of the next VOR and returned to NAV. Don't know if that's the correct procedure but it seems like the simplest.David

Hey, sounds like you flew some older equipment for sure. Maybe it just needed a slight tune up. Now IRC? I am not in the recall mode at the moment on IRC, except for Internet Relay Chat? And surely that isn't it? Archer response sounds like the Mooney Bravo. Well we can live with that. Try the Learjet for the difference, or the C-172. Thanks for joining in here. Glad to have your comments. I see that your PC is probably a lot newer than the autopilots you flew. Have to say I'd like to know the old "frame rate."

Geof:I am going to try that MAP situation first thing after I close out here. Good idea. Now, will my aircraft crash and burn as I taxi through or over the VOR station. Should I just use a TVOR? Ha. Let me know about your FS2004 Model 33 if you can. I lost track but used it a lot in MSFS2002. I don't actually put a lot of stock in that cross wind answer either. But glad the pilot volunteered it.

Onetinsoldier has a fs2004 patch for the deb-you can get it here:http://library.avsim.net/sendfile.php?DLID=38004Weather permitting I'll take it out on monday and try the nav mode on the stec 50-I suspect your hypothesis is correct.http://mywebpages.comcast.net/geofa/pages/Geofdog2.jpg

Brother mine: Good analysis. I like your reply and contribution. You bring new life to this question with some thoughts only someone besides myself could have, at least at the moment. As for the "nap," well I usually did that well out between two VOR stations. And when the passengers woke me, which they indeed did, I had to twist the CDI or bearing indicator knob a bit to locate the stations and get them a fix. They were polite enough to ask, "Where are we?" But, thank goodness I recall that happening only once.

Actually that should have been IIRC, which stands for If I Recall Correctly. I've locked the frame rate at 25fps, and I suppose it stays there because I never look at it.

For some more input here, I have just finished flying across the Hondo, Texas TVOR at 200 feet in the C-172 (T-41 for you military types). With an altitude of 200 ft AGL and cruise speed, the Cessna gets on by the "Ccone of silence" quickly. Also the radial being flown is very, very narrow at this point. Think about it. With NAV mode engaged, the sim does turn NAV mode off over the station. But it is possible to keep flying the Cessna and flip it back on about ten seconds later at this miniscule altitude. It wobbles left and right, probably too much. So, magnify that wobble as you climb from 200 feet upward and you soon see that re-engaging the NAV mode while on autopilot too quickly is a real problem. At 10,000 feet you're in real trouble. So for now we'll have to punch off NAV prior to the station, and go to HDG hold. Wait till we have a good radial lock on the far side of the VOR and go back to NAV mode (if we like to fly this way). Let's keep getting positive feedback on this if there is anything to add. Thanks all for your help here.