Checking VOR and radial headings

[Graham Pollitt]

Is it possible and if so can anybody please give pointers for the following example :

The plane is right above VOR named 'TEST' and you want to fly to VOR 'TEST2' on the 180 inbound. Both VOR have DME.

Im assuming the offset can be read for the VOR identifiers/DME etc (Had a quick look at the offset list and can see various related offsets).

So how can I check to see if the plane is on the 180 inbound to 'TEST2'. If I read the heading of the aircraft how can I check the position in relation to the VOR and a specific course. No doubt there is some maths involved here but I havent a clue what to do.

Many thanks

Graham

[Pete Dowson]

So how can I check to see if the plane is on the 180 inbound to 'TEST2'. If I read the heading of the aircraft how can I check the position in relation to the VOR and a specific course. No doubt there is some maths involved here but I havent a clue what to do.

You can read you aircraft's position (latitude/longitude) and the position of the TEST2 VOR (also latitude/longitude). The rest is trigonometry. Your VOR 'TEST' is not relevant of course, it is the aircraft position which is relevant.

If the VOR is a close enough (which presumably it is for good reception?) you can probably get away with simple plane trigonometry, assuming a "flat Earth" for the distance involved. However if it is too far then you need spherical trig and great circle calculations, which get complicated. I could probably help with the former, but you'd need to look up the formulae for the latter elsewhere. Google will find plenty of course, search on Great Circle Navigation or similar.

By coincidence, there's another thread here (http://forums.simflight.com/viewtopic.php?t=50633) which is very recent and also implies that there may be a way for FSUIPC to provide the bearing to the VOR directly. I am prepared to do this but I am still awaiting a reply from the poster there.

Regards,

Pete

[Graham Pollitt]

thanks Pete

hopefully you will be able to find out if there is another offset to used, Im sure it would come in very handy for myself!

I will play around with the VOR offsets later in FSInterrogate and see how they work in relation to my aircraft.

Not done any trig for a while, have to research on net. I remember SOH CAH TOA or something :)

Regards

Graham

[Graham Pollitt]

[quote name="Pete Dowson

Your VOR 'TEST' is not relevant of course' date=' it is the aircraft position which is relevant.

[/quote]

I know, my question originally was to find out the course outbound but I added another VOR and made it inbound. Dont know why !

[Pete Dowson]

hopefully you will be able to find out if there is another offset to used, Im sure it would come in very handy for myself!

Okay, I have found that the bearing details are availble for FS. These are relative bearings -- in other words you have to add the aircraft heading to them to get the actual direction to the VOR. the values are from 0 to 359 (whole degrees only) and are those shown on the RMI (bottom left on the default 737) when you have the aircraft heading 0.

I've mapped them to 0C56 (16-bit/2 byte) for VOR1 and 0C5C (16-bit/2 byte) for VOR2.

This facility will be in the next interim update to FSUIPC which I shall release within the next few days. Please keep your eyes on the Announcements above.

Regards,

Pete

[Graham Pollitt]

Thanks a lot for the effort in producing the update

Im sure your efforts will be appreciated by more than just myself!

Regards

Graham