Hi Captains,

 

Noticed today when flying to a VOR in nav mode that the aircraft was off to the right of the route showing on the GPS. VOR 1 was set correctly to the course defined in the flight plan so i'm assuming the route displayed on the GPS should be exactly the same.

 

I understand the plane may fly a corrected heading doe to winds but I'm assuming it should still stay on the route shown

 

The strange thing is I have been sim flying for many years but only just noticed this !!!! It maybe because I have been flying the heavies for a ling while and only just got backm into GA flying.

 

Any ideas would be greatly appreciated

 

The screen shot shows a route from EGMH to the COA VOR on the 90 degree radial in nav mode, default cessna and no wind. You can clearly see the plane off to the right. If I flip the switch to GPS navigation the plane flys to the left to pick up the route.

 

Best reagrds

Simon

Hi Simon

 

No screenshot?

in my understanding is the button for gps the right one to follow the track with the vor

switching to the nav button is only for approaching the runway with ils.

so a few miles before landing you switch the gps to nav

What are you using for Flight Planning?

 

Is it possible that the various base documents are of different vintages,

hence some changes in magnetic variation?

 

Also, if the HSI drifts a bit (hit the D button to reset), you get this kind of behavior.

Shouldn't your nav button be set to GPS instead of vor1?

I hope you entered the course heading! If it is not set right, you'll be placed right or left of the runway.

 

Best regards,

Jim

The other thing is, depending on how far away you are, the VOR isn't that accurate (but good enough for the purpose) and (stand to be corrected here) the GPS shows the great circle route and the VOR doesn't work that way, unless your track happens to be a great circle, which your example isn't.

 

Mike

Thanks for the interest guys. I have added (I hope) the screen shot this time

 

What it shows is the flight plan from the default fsx flightplanner showing a 90 degree heading to the COA VOR. The magenta line in the gps also dispalys the 90 degree course to follow.

 

If I have the navigation mode set to GPS then the plane follows the line perfectly showing a 90 degree course and heading (no wind). As soon as I switch to NAV mode (because I just wanted to use the GPS as a moving map) and fly to the VOR using VOR1 (set to 90 degrees) the plane veers of to the right and adjusts its course to fly to the VOR at about 86/87 degrees instead.

 

The misallignment is also visible in the FSX map display. As I said earlier I have been flying the heavies for a while and only just got back into GA flying but dont ever recall it doing this.

 

So I guess the question is, is this the correct behaviour or is my installation at fault.

 

I appreciate the help

 

Regards

Simon

Edited October 15, 201213 yr by firehawk44
Photo deleted - 1600W max - your's 1950W; 400KB limit - your's @550KB. Please repost with proper sizes.

ok, I got the picture and the correct size limit this time

 

Simon

Simon,

 

I believe this is just a quirk of MSFS, not your system. I've seen the same thing with the Reality XP GNS530, when I fly using the VOR indicator. If you adjust your map range (i.e. zoom out), the aircraft symbol will probably align with the magenta line more closely. I know it's a little annoying, but know you'll get to your destination all the same.

 

Todd

Look at this: http://www.navfltsm.addr.com/vor-appr.htm

 

Some VORs are not located on the actual airport. The one where I fly mostly is on a mountain top about 4 miles away. Close enough to get you there but not onto the runway. Just a thought.

 

John

In this scenario the magenta line will be the shortest path between waypoints.

 

The odds of that line landing directly on a radial are slim at best.

 

You could also be tracking the 269 degree radial, being one degree off is not hard with the sim VOR heads.

 

If I remember correctly, being one degree off at 60 miles out would put you 1 mile off course.

 

I have been flying sims for years and what you are seeing is typical of what I also see.

 

It ain't perfect, but not bad for a $30 piece of software.

 

In my opinion, pick either the GPS or the VOR and fly it, using the other as a backup.

 

regards,

Joe

If you're inclined to experiment, find the same situation in the deep south and you'll find the magenta GPS line is south of the VOR track. Do it on the equator (or any north/south track) and they should line up. If you do, post the result - I'd be interested to know. Joe remembers correctly - 1 in 60.

 

Mike

The GPS plots a track from the center of the airport to the VOR, it doesnt care about radials. If you want them the match, center the plane on the GPS track line then tune the OBS to the VOR.

If you install FSTramp you can hover your mouse over a VOR and it will tell you that in almost all cases VORs have a slight offset built into them. For example with Spokane VOR (GEG) FSTramp reports "NAV/OBS bearing = Mag. bearing - 5 deg" which means that for a mag course of 253° you'd need to dial 248° into the OBS to fly that actual course over the ground (direct to KSEA). Making this adjustment will put you much closer to the pink line on the GPS but you still won't be able to track it perfectly - that's something that just doesn't happen. Close enough to get you to your destination though.

 

PlanG v3 apparently has a similar function, I'm still trying to figure out how it all works myself at this point, this is more for my own amusement than anything else, just thought I'd share as it seemed relevant to this thread. Take it with a grain of salt :smile: . What you can to do is right click the VOR in PlanG and choose "show radial". That pops up a dialog where, using GEG as an example, you can type in 248° and a distance of 190nm. That creates a line directly to KSEA. It's a cut & try thing, type something in and see if the line leads to the desired destination/waypoint, if not, type something else in until it lines up, then dial that value into the OBS.

 

Apparently if you use a VOR as a waypoint in the flightplan, this offset is taken into account and when you view the flight plan in the "plan panel" (Shift+1), the magnetic track shown is what you should dial into the OBS. If you create an arbitrary user waypoint however so that the magnetic track crosses the VOR however without actually including it in the plan, the magnetic track in the plan panel will show a completely different value. In this case the offset appears to be -4° rather than -5° as reported by FSTramp, probably due to rounding differences between the two programs I would imagine.

 

Here are a couple screenshots to illustrate what I'm talking about, first is a plan including the VOR, second is a similar plan using an arbitrary waypoint where the track crosses the VOR, note the differences in the magnetic tracks highlighted in red:

 

 

 

 

Here's a .zip file that contains the actual plans I made for this experiment if anyone wants to open them in PlanG and see for themselves. Also included are actual .pln exports for use in the sim, and you'll note that the kneeboard navigation log reports a course of 253° for the last leg of the flight regardless of which .pln you load:

 

http://www.cat-tamer...plan_g_test.zip

 

Jim