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Standard altimeter settings or QNH


Mitchos
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Hello

 

It might be useful to have the ability to choose the altimeter settings in mission editor.

 

We may have to choose AGL, QNH or Standard Altimeter Setting when we create the mission.

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Why would you need to choose this in the mission editor? There is already a weather selection system that allows for differing pressures (albeit a poor one, but luckily that will be all remade in the 2.7. patch) if that is what you mean. If you mean an option to preset the aircraft to show QNH/QFE/STD from the getgo then I really would call that more of a waste of resources... there is a knob in each cockpit to alter that already when in game. Making a feature to save a couple of seconds in a game is simply a lazy request I'm afraid. 

DCS Finland | SF squadron

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Posted (edited)

Understood what you mean.

I fly the Hornet and I change my settings 5/6 times per flight. QFE then crossing A/D CTR i set QNH as per mission briefing, then crossing TRANSITION ALTITUDE i set standard, except if we brief to be QNH all flight long.

 

What is missing in my statement is an example:

 

So I set a Tanker at 21000ft MSL So with QNH as reference. let's say 30.85 all in ME.

Flying the mission:

I join the tanker 1000ft below so typically flying at 20000ft. So I set 30.85 in my Hornet, and as i reach te tanker, LotAtc sees it at 21000ft, F2 view sees it at 21000 and in cockpit flying along with the tanker my alt is approx 20200ft. But we are 21000ft AGL (remember MSL in ME)

As long AI aircraft do not respect input in ME if we can have a choice with SAS everybody should be at the right altitude if everybody respect SAS.

 

I want it at 21000ft not at 20200ft. if we can have the ability to set every AI assets at the same setting it would be easier.


Edited by Mitchos
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  • 2 weeks later...

Ah, now I get what you were after! Yeah that makes sense. I believe when you set altitudes to waypoints you can set it either AMSL or AGL, but I've found these are almost never exactly what I set them to (theres probably something missing in how the altimetry is handled there)... so technically it is there already but does not quite work as one would hope. And of course the STD setting is not there.

 

Sure, the controls for altitude could be more clear for AI.

 

Regards,

MikeMikeJuliet

DCS Finland | SF squadron

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On 3/20/2021 at 3:46 PM, Mitchos said:

So I set a Tanker at 21000ft MSL So with QNH as reference. let's say 30.85 all in ME.

Flying the mission:

I join the tanker 1000ft below so typically flying at 20000ft. So I set 30.85 in my Hornet, and as i reach te tanker, LotAtc sees it at 21000ft, F2 view sees it at 21000 and in cockpit flying along with the tanker my alt is approx 20200ft. But we are 21000ft AGL (remember MSL in ME)

As long AI aircraft do not respect input in ME if we can have a choice with SAS everybody should be at the right altitude if everybody respect SAS.

 

I want it at 21000ft not at 20200ft. if we can have the ability to set every AI assets at the same setting it would be easier.

 

The real reason for you problem is how the AI are coded to fly.

Currently, any AI aircraft fly at a "DCS true altitude", (ie exactly 20,000ft above msl), regardless of air pressure/temp or altimeter setting. This means for instance, that if you assign a tanker altitude of 25,000ft in the ME, they may be +/-1,000ft (or worse) when flying the mission. Altimeter settings are basically irrelevant for all AI aircraft. Not ideal when playing single player, as you can imagine.

 

I logged it as a bug here, but it hasn't got any response at all. I figure they know about it, but it's just too hard or they don't care.

 

 

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9 hours ago, IkarusC42B Pilot said:

This whole thread confuses me so much. So just for refference

QNH/QFF=MSL

QNE=AMSL

QFE=AGL

 

QNH is altimeter setting reference to MSL so the altitude is displayed as AMSL.

QNE is altimeter set to 1013mb or 29.92mm. The last setting is used above transition altitude so that all aircraft in a large area can be on the same altimeter setting. Which is important to maintain vertical speration.

 

https://images.app.goo.gl/4ZuhcaqawdMTZciFA


Edited by Sinclair_76
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On 3/19/2021 at 9:06 PM, MikeMikeJuliet said:

there is a knob in each cockpit to alter that already when in game

Not working in the Eagle 😕

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On 3/20/2021 at 3:46 AM, Mitchos said:

Understood what you mean.

I fly the Hornet and I change my settings 5/6 times per flight. QFE then crossing A/D CTR i set QNH as per mission briefing, then crossing TRANSITION ALTITUDE i set standard, except if we brief to be QNH all flight long.

 

What is missing in my statement is an example:

 

So I set a Tanker at 21000ft MSL So with QNH as reference. let's say 30.85 all in ME.

Flying the mission:

I join the tanker 1000ft below so typically flying at 20000ft. So I set 30.85 in my Hornet, and as i reach te tanker, LotAtc sees it at 21000ft, F2 view sees it at 21000 and in cockpit flying along with the tanker my alt is approx 20200ft. But we are 21000ft AGL (remember MSL in ME)

As long AI aircraft do not respect input in ME if we can have a choice with SAS everybody should be at the right altitude if everybody respect SAS.

 

I want it at 21000ft not at 20200ft. if we can have the ability to set every AI assets at the same setting it would be easier.

 

Don't do this. You have at most three altimeter settings: departure, combat, and arrival. Usually those three are the same. Don't use QFE in Hornet, it's not designed for that. Depending on how avionics are coded the baro altimeter is used to calibrate INS altitude on takeoff roll (A-10, F-16, not sure F-18). The "QNH" that DCS shows in the automatic briefing is actually QFF so depending on field elevation it's not accurate. Don't change to flight level reference in combat. You're not an airliner. Combat aircraft are expected to go from 40,000' to 400' while getting shot at in a few seconds. Use "force QNH" (or simply QNH or QFF) instead.

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4 hours ago, Frederf said:

Don't change to flight level reference in combat. You're not an airliner. Combat aircraft are expected to go from 40,000' to 400' while getting shot at in a few seconds. Use "force QNH" (or simply QNH or QFF) instead.

I completely agree with this. I’ve never understood the logic of using a transition layer in a combat environment. It’s not like I’m going to change my altimeter as I dive from 20k to 10k whilst dropping Mk83s.

 

Keep it simple with one (or two if there’s a significant difference) theatre wide QNH. This is sufficient to provide air to air separation as everyone is on the same setting. Almost all combat aircraft have a rad alt, so terrain separation can be ensured that way, even if the theatre QNH is slightly different to the the actual, current location pressure.

 

Local QNH around the airfield/carrier is the only other setting you need.

 

Now, we just need the DCS AI to actually respect the current air pressure and change their altimeter settings, because this discussion is basically moot until they do, unless playing in a multiplayer, client only mission.

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