Altitude not correct

[Adamastor]

Hi all.

I notice that the altitude (in meters translated into feet) has a deviation of about 200 feet down.

That is, if I make a trigger on the ME for a certain altitude, for example at 10000ft at 9800ft it triggers.

If I make a correction in the QNH to 30.13 (and in the mission I use 29.92 default) I get the correct altitude on the altimeter (I guess is fake, but does the job)

Could I be misunderstanding or is it a bug?

I tested only on the A-10C.

[Frederf]

Barometric altimeters, even with the correct QNH do not show true altitude. The explanation is semi complicated and involves other factors. You should compare the barometric cockpit altimeter with the true altitude reading of the DCS info car.

[Adamastor]

Barometric altimeters, even with the correct QNH do not show true altitude. The explanation is semi complicated and involves other factors. You should compare the barometric cockpit altimeter with the true altitude reading of the DCS info car.

 

Thank you Frederf. True is that in early versions I didn't had that issue, now all my training missions are different.

I even went to A10 BTQ missions and confirm that. There is a "window" for level turns and i was getting the annoying "Terminate, Terminate ... you are above .... "

And if I set QNH to "trick" altimeter it worked.

As I say, before I had't any issue, only a Q- on BTQ :)

[Frederf]

Ideally the mission maker does everything by USAF procedure (e.g. QNH) and then finds out the instrument-to-true relationships for all altitudes and writes them down. Then he goes into the ME and sets the true altitude limits in the triggers to correspond to what the pilot sees.

[Rudel_chw]

There is an effect caused by ME air temperature, see this:

 

https://forums.eagle.ru/showthread.php?t=245172

[Adamastor]

Thank you Gent's

I think I have another study case in hands.

If is for realism, is great!!! :)

[marcwoolery]

Speaking of Altitude ... when using F2 to view other aircraft, seems the Speed and Altitude indicated at the bottom of the screen is never accurate, Can anyone explain this ? I mean off by 50% or more ??

[Frederf]

Info bar (F2) shows a speed and altitude. The two options are IAS and TS in units set imperial or metric in the gameplay options (kn/ft or kmph/m). This is completely independent of how the cockpit instruments display speed and altitude both in method and units.

 

"IAS" on the info bar isn't really IAS. It's a true air speed modified for air density. I haven't done the tests but it's similar to EAS which is a very calibrated value. It will be closest to your airspeed gauge roughly. Real airplane instruments have all sorts of reasons why they show a different number than the info bar IAS value from temperature to compression to humidity to installation error. 50% is a lot though, I would expect probably within 10% normally.

 

"TS" is true speed which is the actual speed of the simulation object through the X Y Z coordinate space. It's sort of like groundspeed without the issue that vertical motion isn't included in groundspeed.

 

Altitude is similarly perfect information. It shows your Y coordinate in the X Y Z coordinate grid multiplied to by a conversion factor to show feet or meters. You shouldn't expect it to match your cockpit instrument perfectly since the simulated instruments have all sorts of pressure and temperature (and more) effects that will read different than perfection just as the real airplane would. Errors can be a bit larger depending on the exact situation.

 

If you can describe the exact situation then the differences can be examined. E.g. "I was flying a MiG-19 which was showing 500 km/h IAS and 5,500m altitude but info bar said 513 km/h and 4,326m. The weather was 22*C 755mmHg QFF" or similar. Otherwise there are too many factors.