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[NOT A BUG] The problem with Beslan...


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Is there a problem with Beslan's runway/ILS system?

 

The ATC calls it runway 10, the number on the runway is 10, the mission editor says the ILS localizer is 094. In real life the runway is 09.

 

The plane's heading tape on the HUD has it at somewhere between 080 and 090, and the ILS seems to agree roughly with the mission editor.

 

Is this a known problem with some of the Caucasus runways/ILS?

 

Or am I missing something about runways/ILS?

 

Edit:

I read that runways might need to be renumbered due to changes in the Earth's magnetic field, and on Google earth you can see that Beslan has been renumbered from 10/26 to 09/27. However, surely the simulator is not modelling this movement in magnetic north, right?

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"We could come back with hydraulics shot out, half the tail shot off, piece of the wing shot off, we had two engines and could come home with one... She really was a piece of machinery that you could fly into hell and back... And she was designed around that gun from day 1"

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There are two directions in DCS: ruler and longitude. On top of that there is the declination field which is an adjustment to arrive at a magnetic heading. There are four possible combinations of these and which you consider correct is arguable. Ruler is considered true heading for UI and avionics purposes. In reality angles with respect to lines of longitude are by definition true heading. Magnetic heading for avionics purposes is ruler plus the adjustment. In reality magnetic heading is not caused by an adjustment, instead the adjustment describes the difference between true and magnetic. The declination field is reasonable in DCS and adjusts ruler heading to magnetic.

 

And yes, magvar is different in DCS depending on both time and place. You can try two airports in the years 1900 and 2100 and get four different numbers.

1900 Beslan 4.8

1900 Batumi 4.1

2100 Beslan 12.7

2100 Batumi 12.2

 

AIP data for RWY10 URMO is 101°29' TH, 94(.5)°MH

Real longitude line relative to north is 0° by definition

DCS data for the same runway is 93.5° RH (ruler heading), 86.5 RHCD (ruler heading corrected for declination)

DCS longitude line relative to north is -8° by ruler measurement

 

In both cases the difference between true and magnetic is 7° which is reasonable. A real airplane which had appropriate displays of TH and MH would show 101.5 and 94.5 parked on the runway while a DCS airplane shows 93.5/86.5. By either measurement of MH those both round to RWY 09 not RWY10.

 

The last piece of the puzzle is time. If declination is less than 6.5° then it could be argued that 101.5-6.5=95 which should round to RWY10. Of course the magnetic display of a DCS airplane would still be 87°. This crossover happens for all dates earlier than about January 2010. Presumably the real runway was labeled RWY10 in the past when the declination was less than 6.5. There's also the idea that Soviet runways were probably not labeled for their magnetic heading but instead their true heading as that's the reference that nearly? all Soviet military jets used.

 

If your job is to label the DCS runway it quickly becomes apparent that making something which is correct for all dates, all externally referenced charts, and the internal magnetic compass is impossible.

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Wow, what an incredible answer Frederf, thanks..

 

magvar is different in DCS depending on both time and place.

This is astounding to me.. I didn't think the sim would have this level of detail.

 

But then of course that raises the issue of: "if you're updating where magnetic north is, but you can't update runway numbers, then there will eventually be problems". Maybe that's something beyond the sim's capabilities.

 

It sounds like what you're saying is, Beslan is on the brink between 09 and 10, and indeed the real airfield has been changed for reasons like that which you describe.

 

Thanks

"We could come back with hydraulics shot out, half the tail shot off, piece of the wing shot off, we had two engines and could come home with one... She really was a piece of machinery that you could fly into hell and back... And she was designed around that gun from day 1"

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