Runway heading discrepancies

[Pinefang]

So I think that I understand why the runway headings are not shown along the magnetic headings on the runways but what I don't understand is why does the CDU Divert page list these headings and not the true magnetic headings which would be so much more useful when landing under ILS conditions. So many times I am practicing ILS landings in low visibility conditions and when I break out of the fog I'm way off of the runway. I know that every airman should have their charts with them for this info but I just don't understand the sense in not having them in the CDU Divert page. Can any one ELI5.

[159th_Viper]

To make a very, very long story relatively short, the majority of airbases in DCS are incorrectly modeled/placed insofar as their geographical locations are concerned. As a consequence great discrepancies exist insofar as True Headings/Magnetic Headings and calculations regarding magnetic declination are concerned. It is this error which then also filters down to the CDU.

 

Best course of advice is to rely solely on the fictitious DCS Airbase approach charts as provided in the Docs folder for ILS navigation.

 

And no, problem is not solvable at this stage. Workaround is the custom charts as stated above.

[PFunk1606688187]

In real life runway numbers are almost never the same as the runway heading, even if its off by just a degree. The problem is that because of these errors in DCS you end up with runways being almost 10 degrees off so its counter intuitive to the standard runway naming conventions.

 

For instance as an A-10 pilot at Vaziani its Runway 14 and 32 but the runway magnetic headings are actually about 131/311 respectively. In real life they'd be renamed to runways 13 and 31 but we just have to make due.

 

In any event there'd never be an ILS approach in real life without an approach plate anyway. However the ones that come in the DCS Doc folder are... weird. They look like some weird like combination GPS and visual with ILS but without most of the standard ILS plate info, like there's no localizer final heading or any coherent descent profile or minimums. As someone who flies VATSIM in FSX regularly they are totally alien to me.

Edited September 6, 2014 by P*Funk

[Pinefang]

Thanks for the replies. I think it is unfortunate that the CDU info is inaccurate. But as suggested I will use the plate info for correct heading info and hope some day the CDU info is corrected.

[Wolf Rider]

Magnetic North wobbles around, in the real world, a bit as well...

[159th_Viper]

Magnetic North wobbles around, in the real world, a bit as well...

 

Magnetic Declination is factored into the SIM in DCS. Varies year to year at specific locations as well, which is also factored into DCS.

[towsim]

If you use the VAD charts from the DOC/Charts folder, you need to know:

In the real world there are two main sets of charts. For IFR and for VFR. The VAD charts cover VFR only. ILS, VOR, NDB, TACAN and GPS approaches are subject of the IFR set. Therefore, you find no details for ILS approaches in the VAD charts with the exception of their frequencies. The IFR set does not exist up to now.

Since DCS has a mix up of north references , two sets of VAD charts exists. DCS_VAD_Charts_A10C.pdf is especially for the A10c and observes magnetic north. As a result, you will see the published magnetic runway heading from the VAD charts on your HSI, if you are aligned with the runway. The second set ,DCS_VAD_Charts_FC3.pdf, covers the FC3 aircraft which are orientated to another north reference, probably true north. Even here, you will see the published runway heading on the HSI, if you are aligned with the runway in a FC3 aircraft. But do not expect, that true north and magnetic north are that what you find on real world charts. It is anywhat, created by ED.

[effte]

And no, problem is not solvable at this stage. Workaround is the custom charts as stated above.

 

Now, I hadn't heard that before in the gazillion of pages of discussion on the subject. It could do with a bit of an explanation as to 'why'. If there is indeed a reason, it would save both user and devs some aggravation to just spill the beans.

 

My guess: We are flying over a flat earth model, utilizing a slightly unfortunate projection?

 

It would be interesting to know the details for the purpose of nav exercises as well, something we have been having a lot of fun with with the introduction of the F-86. Up to now, the ded reckoning legs haven't been long enough for it to matter much, but as patience levels increase with old age in the participants that might change...

[sobek]

My guess: We are flying over a flat earth model, utilizing a slightly unfortunate projection?

 

Yes, projection error.

[effte]

Thank you for the confirmation.

 

That is somewhat cumbersome to get around, at least without introducing issues in other areas.

 

Do you know, or can you ask the devs, which projection has been chosen, standard parallells etc? It would be somewhat useful.

[159th_Viper]

Now, I hadn't heard that before in the gazillion of pages of discussion on the subject. It could do with a bit of an explanation as to 'why'. If there is indeed a reason, it would save both user and devs some aggravation to just spill the beans....

 

Inattention to exact detail would be a concise summary.

 

Keeping in mind that the original map was coded/modeled more than 10 years ago, exact attention to detail to the nearest degree was obviously not expected nor required, especially considering the flyables at that stage, hence the discrepancies we see at present relating to airbases whose geographical locations all have varying degrees of errors.

 

Then again, some are perfectly aligned to their RL counterparts. One must also keep in mind the differing technology used in upgrading the map etc etc - old airbases differ from new, different Devs tasked at different times with different bases etc etc. All this adds up to the errors in modelling we have to date - all perfectly reasonable.

 

Yes, in a perfect world it can probably all be fixed, but at what cost?

 

Senaki is a good example of an airbase modelled 100% correct according to true/magnetic and declination values. Others not so much by varying degrees. Point is that to now go and remodel the entire map to rectify past errors in modelling reasonably made is just not, I assume, productive or cost-effective in the greater scheme of things.

 

As simple as that: Honest mistakes easily made that are now beginning to show due to the enhanced fidelity of the simulation.

[towsim]

http://forums.eagle.ru/showthread.php?t=126899

Post #10

[effte]

towsim,

that is a nice writeup. I think I'll save myself the hassle of retyping and send people that link in the future. I'd rep, but apparently I can't so you get the appreciation here instead!

 

I have adapted a navlog spreadsheet of mine for DCS use with the grid correction added, but with a known projection and a couple days off with autumn weather it could be possible to automate that and save the hassle of checking the alignment in the editor... anything to stop me from just going out anyway and becoming cold and miserable. :D

 

Cheers,

/Fred

[cichlidfan]

To make a very, very long story relatively short, the majority of airbases in DCS are incorrectly modeled/placed insofar as their geographical locations are concerned. As a consequence great discrepancies exist insofar as True Headings/Magnetic Headings and calculations regarding magnetic declination are concerned.

 

Then why do different aircraft show different headings in the same location? If the problem is the map, then all aircraft should be affected the same way.

[159th_Viper]

Then why do different aircraft show different headings in the same location? If the problem is the map, then all aircraft should be affected the same way.

 

Who knows? Personally never heard of it/given it a second thought.

 

Care to elaborate regarding planes/locations etc etc?

[cichlidfan]

Who knows? Personally never heard of it/given it a second thought.

 

Care to elaborate regarding planes/locations etc etc?

 

There are FC3 charts and A-10/BS2 charts. They are different. Why?

[159th_Viper]

There are FC3 charts and A-10/BS2 charts. They are different. Why?

 

Referring to the canned charts in the Doc folder?

 

Magnetic Declination. One set are true while others are magnetic it seems.

 

Why is that so? Have to ask the author/pilots. More than that I have no idea I'm afraid.

[cichlidfan]

Are you saying that this is not true?

 

Since DCS has a mix up of north references , two sets of VAD charts exists. DCS_VAD_Charts_A10C.pdf is especially for the A10c and observes magnetic north. As a result, you will see the published magnetic runway heading from the VAD charts on your HSI, if you are aligned with the runway. The second set ,DCS_VAD_Charts_FC3.pdf, covers the FC3 aircraft which are orientated to another north reference, probably true north. Even here, you will see the published runway heading on the HSI, if you are aligned with the runway in a FC3 aircraft.

[159th_Viper]

Are you saying that this is not true?

 

Did you not read what I said?

 

I said one set is magnetic while the other is true. How is that any different to your quote?

 

 

 

 

Ps: Are you asking why the A-10C relies on magnetic while others (?) rely on true insofar as the HSI is concerned?

 

Further edit:

 

If that is indeed so, I had a quick look and it seems that there are 4 possible HSI values one can get depending on location/flyable. Why this is so I do not know, suffice to say that I have asked and will let you know as soon as I know.

Edited September 7, 2014 by 159th_Viper

[effte]

Are you saying that this is not true?

 

Part of it is.

 

The other part is magnetic. ;)