Cabin Altitude problem

[Amaury06 1]

Hi folks !!

Wonder if anyone has had a similar issue. I haven't been able to complete any long haul flights because I get this Cabin altitude alert. At the same time this happens, the A/P seems to ignore VNAV and LNAV for it starts either climbing or descending and also it deviates from the planned route path. I have actually timed the occurrence of this problem and it happens every one hour during the flight(mostly during cruise, although it has happened during any phase of flight) Now, the curious thing is that the problem stops by pausing the simulation for a few seconds and then the A/P regains control, but then after exactly an hour  the problem reappears again. Packs are on and cabin pressurization is on Auto but still I don't know what could be causing this issue. Thanks

[Faisal 0]

Hello,

 

The cabin altitude warning happened to me once. It was after a tail strike on departure. 

[GodAtum 69]

I had the same issue. I had to reinstall the 777.

[mfrantz 45]

Hello,

 

The cabin altitude warning happened to me once. It was after a tail strike on departure. 

 

If you had a tail strike and did not perform the required checklist actions (depressurize aircraft, stay below 10,000 ft, land as soon as possible) there is a small chance you may get a rapid decompress failure if you climb to a high altitude (caused by structural damage on the tail). This depends on the differential pressure at the cruise altitude. In most cases you can get away with it, but there is a very small chance this may happen.

[777simmer 117]

yes, i would say something is wrongt there with the installation.

 

The usual trouble shooting:

1)Run not overclocked and see what happens.

2)FSX should not be installed in the default programs folder.

3)FSX should be excluded from anti virus scanner.

4)Try deleting the FSUIPC.ini file if you are an FSUIPC user (you will loose all Joystick setups you have saved, so maybe make a backup before deleting it. Just in case this was not the problem and you want your settings back).

5)When I have problems, I usually also delete the FSX.cfg file so that FSX builds a new one the next time it boots. And then I enter the PMDG recommended fixes in that file again. However since your problem is PMDG specific, I dont think deleting the FSX.cfg file will help.

 

If you ARE going to try a reinstall:

Install with right mouse click/as administrator.

Install with antivirus software turned off!

Install while not being overclocked!

[Amaury06 1]

Curiosly

 

yes, i would say something is wrongt there with the installation.

The usual trouble shooting:
1)Run not overclocked and see what happens.
2)FSX should not be installed in the default programs folder.
3)FSX should be excluded from anti virus scanner.
4)Try deleting the FSUIPC.ini file if you are an FSUIPC user (you will loose all Joystick setups you have saved, so maybe make a backup before deleting it. Just in case this was not the problem and you want your settings back).
5)When I have problems, I usually also delete the FSX.cfg file so that FSX builds a new one the next time it boots. And then I enter the PMDG recommended fixes in that file again. However since your problem is PMDG specific, I dont think deleting the FSX.cfg file will help.

If you ARE going to try a reinstall:
Install with right mouse click/as administrator.
Install with antivirus software turned off!
Install while not being overclocked!

Hi !! Curiously the same issue is happening with my NGX 737. Don't know why. 

[Dan F 6]

Was just about to post the same issue.  Climbed to FL380, went to Auto Cruise, and then the aircraft seemed to lose altitude slightly.  After that all hell broke loose and the AP was essentially useless.  If it was a tail strike then PMDG did an amazing job simulating an explosive decompression and non-catastrophic loss of a the rear pressure bulkhead.  This was on an AAL flight from KMIA to KLAX.

 

Tried an AAL flight today from KMIA to SAEZ and climbed to my designated cruise altitude of FL350, engaged Auto Cruise and stepped out for a bio break and coffee refill.  When I returned the aircraft was at sea level wobbling around stalled with Wheel Well Fire annunciation on the MFD and my brake rotors glowing red hot.  I assumed it was my fault however for running the center tank dry while on Auto Cruise.

[willywonka 36]

 

 

When I returned the aircraft was at sea level wobbling around stalled with Wheel Well Fire annunciation on the MFD and my brake rotors glowing red hot.  I assumed it was my fault however for running the center tank dry while on Auto Cruise.

That's not a very good assumption. How could having dry center tanks cause a wheel well fire?

[Amaury06 1]

Was just about to post the same issue.  Climbed to FL380, went to Auto Cruise, and then the aircraft seemed to lose altitude slightly.  After that all hell broke loose and the AP was essentially useless.  If it was a tail strike then PMDG did an amazing job simulating an explosive decompression and non-catastrophic loss of a the rear pressure bulkhead.  This was on an AAL flight from KMIA to KLAX.

 

Tried an AAL flight today from KMIA to SAEZ and climbed to my designated cruise altitude of FL350, engaged Auto Cruise and stepped out for a bio break and coffee refill.  When I returned the aircraft was at sea level wobbling around stalled with Wheel Well Fire annunciation on the MFD and my brake rotors glowing red hot.  I assumed it was my fault however for running the center tank dry while on Auto Cruise.

Try with the NGX 737 if you have it and see if the same situation occurs. It happened to me. I'm guessing it's some sort of cabin pressure config problem, I dont know. When this happens I pause the simulation and then the auto pilot magically recovers, but only for exactly one hour and then it goes crazy again. 

[ialej95 0]

Same problem here,

I do the pause unpause thing and it recovers, but as you can understand, I've not payed 90$ to have a cabin decompression in every flight, and having a crazy AP... Making me unable to perform a normal flight without any problem...

Please help!

Thanks, 

Alex

[777simmer 117]

Same problem here,

I do the pause unpause thing and it recovers, but as you can understand, I've not payed 90$ to have a cabin decompression in every flight, and having a crazy AP... Making me unable to perform a normal flight without any problem...

Please help!

Thanks,

Alex

Have you tried what I posted #5 above?

 

Are you guys by any chance starting from a saved flight?

 

Also, if this happens each hour exactly, then take a look at the "AIR" Synoptcs page and see what cabin altitude stuff is doing right before the problem starts.

[ialej95 0]

yes, nothing changed... :(

[777simmer 117]

yes, nothing changed... :(

Thats crazy.

 

Hmm

 

You have to try to get back to basics as much as possible.

 

Disconnect Hardware, no trackIR/controllers for now, just use the keyboard.

 

No weather or other software running.

 

No FSUIPC (just get rid of it for now)

 

And if after all that, and of you already tried a CORRECT reinstall procedure, then contact PMDG cause I dont know what else to come up with.

[dondormehl 0]

Gents,

 

I have experienced exactlly these above mentioned symptoms on all my PMDG aircraft (744, T7 and NGX).

 

I have recently bought a new PC and installed only my PMDG fleet. What I did not notice was that my system date/time was all whacked due to a dud CMOS battery.

 

The PMDG products didn't activate properly and subsequently some modules deactivates at specific times when a flight is started!

 

PMDG advised me to re-install as they think the activations did not take properly. If your products don't activate correctly you will see these weird behaviours! Very frustrating as I have lost about 6 long haul flights!

 

I have replaced my CMOS battery today and will re-install tomorrow. Fairly confident that this will fix this problem.

 

Check your system date/time! Most likely the culprit.

 

Cheers,

[Felix91 0]

Thank you so much !