Altimeter doesn't work in some starting conditions

[Jowen G. Bruère-Dawson]

Hi,

The baro altimeter doesn't work when you are starting on parking hot or runway. When you want to set a pressure, the pressure value does change, but the altitude needle and indicator doesn't move. When you take off, the altitude doesn't change.

It does work when you start in flight or in cold and dark state.

Thanks

[MAXsenna]

Hi,
The baro altimeter doesn't work when you are starting on parking hot or runway. When you want to set a pressure, the pressure value does change, but the altitude needle and indicator doesn't move. When you take off, the altitude doesn't change.
It does work when you start in flight or in cold and dark state.
Thanks

Can you provide a track for the devs? What Airport is this, or rather. What's the elevation?

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[gulredrel]

Track would be helpful. Also there is a random instrument setting feature in the MB-339. Assumed during the last flight, the ambient pressure was totally different, the setting will be like this during spawn. You need to set it to the correct current value.

Also I've posted this long time ago, I don't think this has been changed, so be aware when having a different sea level pressure than standard atmosphere (29.92" Hg / 1013 mbar):

 

[Jowen G. Bruère-Dawson]

On 5/1/2024 at 1:29 PM, MAXsenna said:

Can you provide a track for the devs? What Airport is this, or rather. What's the elevation?

Sent from my SM-A536B using Tapatalk
 

I'll try.

The airport was Andersen Airbase on Mariannas. Can you try on your side ?

On 5/1/2024 at 4:39 PM, gulredrel said:

Track would be helpful. Also there is a random instrument setting feature in the MB-339. Assumed during the last flight, the ambient pressure was totally different, the setting will be like this during spawn. You need to set it to the correct current value.

Also I've posted this long time ago, I don't think this has been changed, so be aware when having a different sea level pressure than standard atmosphere (29.92" Hg / 1013 mbar):

 

It does not seems to be a random failure at all since it happen every time at the start if it's a runway or ramp hot start.

[gulredrel]

14 hours ago, Jowen G. Bruère-Dawson said:

random failure

I did not mean random failure but random baro setting of the altimeter on spawn. Will try ramp start at Guam.

edit: Just did a quick test. Ramp start Guam Andersen AFB, default pressure 29.92 / 1013 mbar. Loaded the mission three times.

Altimeter initialized with random baro setting. First time with around 1013 mbar and showing field elevation of 525 ft.

second time initialized with 1010 mbar and showing lower than field elevation which is expected with same ambient pressure:

Third time 1015.5mbar showing higher elevation which is also expected with this setting:

So this looks totally okay as far as I understand the random init feature.

I also had no problem turning the knob and baro drum changed as well as the altimeter needle and the elevation drum.

Edited May 4 by gulredrel
tried to fix images

[MAXsenna]

Ah! The Marianas ain't exactly elevated. I'll try to test when I'm back at my computer. Your screenshots are not showing, and to save a track. Just exit the mission a little while after you see the error. And click "Save Track". Make a relevant file name, and just drag and drop the file here.

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[gulredrel]

Images are fixed for me currently. Something changed in dropbox handling images?

[Jowen G. Bruère-Dawson]

@gulredrel as I said in my original post, altimeter works fine in cold and dark or in flight start. I just tried again and I confirm the bug on my side. It doesn't work with parking hot start and runway start. I've saved a track.

MB339 Altimeter bug.trk

[gulredrel]

Now I see. Took control over your track and was able to set field elevation.

The initial setting for you is 994mbar and the altimeter is showing in fact -250ft:

Turning the know the needle will start moving at 1008mbar

You can set 1013 mbar and you will have ground level elevation at Andersen

 

Conclusion: The baro drum can go lower in pressure setting as the altimeter needle is able to do. I have no idea if this is correct for this kind of instrument turning the elevation drum backwards, but I think this is okay. The are only a few places on earth were you would need to set a negative field elevation.

Edited May 4 by gulredrel

[Jowen G. Bruère-Dawson]

@gulredrelyes, but in cold and dark or in flight starting conditions, it doesn't happen

[gulredrel]

Altimeter is working for me everytime when correct pressure is set, so no bug in this regard.

You could argue it's an initialization bug assuming that in hot start (ramp or runway) the pressure should be set to correct baro value before.

Edited May 5 by gulredrel

[MAXsenna]

@gulredrelyes, but in cold and dark or in flight starting conditions, it doesn't happen

That's because the aircraft is not setup for you in cold and dark, but in hot/flight. Turn to the correct pressure, and it should work. Many modules behave exactly like this.
Cheers!

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