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Airbus 320 altitude issue


Akki

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I fly since several year Airbus series 320/321 in different liveries and is extremely pleased with the performance except for one issue: according to online ATC (VATSIM) my "real" altitude according to ATC is lower than the one I read in cockpit FMC i.e. if I am asked to fly 4000 feet they measure approx 3600 feetat a certain mB, forinsance 1020 to be put in according tp ATC I need to adjust to approx 1013 to level out on 4000ft (approx). Can I adjust the aircraft config in some way to correct this?

Best regards

Åke

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If you press "Shift + Z",  you get several informations about your speed, altitude, heading, wind, your position, screen frame rate (press several time to cycle them)... in the upper left corner of your monitor. As these informations come from the internal sim values, they are just correct. So you can compare them with what you see on your FMC and assess for discrepances eventually.

  

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Roger, now I understand. Great thanks. I thought I could correct any difference between ATC alt reading and my aircraft alt reading by changing a factor in aircraft config.

Åke

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Yes but if the sim tells you that there are no discrepancies between FMC reading and your actual altitude by shift+z..... so what i could guess is that on-line ATC is wrong for some reason

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Hi, I have just tested in a flight. 

 

Condition #1

Clear sky (no external weather software), 1013 mb.

BARO knob: Std

28000 ft selected in FMC

28000 ft reading in PFD

28000 ft of altitude in shift+z info

Fsx's ATC confirmed my FL at 28000.

 

Condition #2

Cloudy sky (by FSXWX freeware weather software), 1005 mb

BARO knob: Std

28000 ft selected in FMC

28000 ft reading in PFD

27750 ft of altitude in shift+z info

Fsx's ATC told me that my FL was 277. But if I changed to 1006 mb (the closest ground weather station), I got 27750 on my PFD. So the apparent discrepancy was because I was in Std (thus always 1013 mb). So to me there are not issue, at least in my airbus installation.

 

 

 

 

 

 

 

 

 

 

 

 

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OK, thanks, but Ive been told at several occasions that I fly " to low" at low altitude from ATC, for instance while vectoring. 4000 feet on FMC says give 3600-3700 feet according to ATC. But they can also be wrong?

Åke

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I've had one single occasion where I changed the altimeter in the A330 (uses the same system as the 320s) was indeed set to STD, but still indicating local pressure altitude, despite actually showing STD on both the FCU and the PFD. There was no way to see that in the flightdeck, only the VATSIM controller noticed.

In that case a reset of the altimeter to local and right back to STD sorted it out and then my altimeter was indicating correctly.

 

Afterwards it never happened in over 500h of testflying this year. The developer checked it and I believe it got fixed (must have been two months ago or the like), so make sure you are on the latest version.
If it still happens with the latest Airbus version you should maybe try it with a different weather engine.

 

No microsoft based flight simulator so far simulates temprature errors on altimeter readings, however I don't know your weather tool and if it simulates them or not.

In real life a warmer air mass expands, thus when you're flying at a certain FL in a warm airmass, all other factors remaining unchanged, you'll have a HIGHER true altitude than at ISA conditions. Similarly when flying in a cold air mass you'll have a LOWER true altitude.

That would of course be shown on the controllers radar scope as VATSIM (and IVAO as well if I'm not mistaken) read true altitudes and then pressure correct only.

All the weather engines I know of do not simulate temprature error, but I have not tried nor heared of your weather engine before, so who knows...

 

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Great thanks Emanuel, I had no knowledge about how the weather generator impact on the actual pressure measurements. I believe that the Microsoft server for "Real weather" is down som my present weather settings are not actaul real life weather. Alessio above gave me a tip on a free weather generator that I will test.

You mention that you made a "reset" of the altimeter-how is that done?

I finally think I have the latest version of the Aerosoft Airbus - how can I check- Aerosoft Update page dont indicate a later version anyhow.

 

Åke

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