Pictures of your flight deck when the beeping is happening would help us troubleshoot, a lot.

 

Post a screenshot of your overhead, main, and radio panel the moment the beeping starts and ends. After that, we can pinpoint the issue.

i will have to check it again tomorow, but as far as i remember the altitudes were set correctly on the overhead panel. what i did notice is that fuel temp was a bit lower then usualy. could it have anything to do with this? i couldnt find anything usefull in the QRH

Fuel temp. has nothing to do with pressurization.

If it is high, it could be that you have a not updated ngx version, this unpatched version suffers of fuel temperature that "rises" until it triggers hydraulic overheat. Completely out of your situation. You also have a different problem, your fuel is cold.

ok, i did the same flight again, sao-paolo to la-paz. crz level 38000, and step to 40000, then decent to the runway at about 13000.

all went well until about 23,000 at the decent- then the beeping started. this is the situation at that moment. any ideas?

 

 

 

 

 

 

You might wanna review the FCOM and/or FCTM (unfortunately, I have neither nearby at the moment). There are special procedures regarding operations at high-altitude airports. Your cabin altitude is at 10,000ft, which is why the Cabin Altitude Warning Horn is sounding. IIRC, you're supposed to set a landing altitude of 8,400ft max., but I'm sure people like Andrea, for instance, can elaborate.

 

So long,

Oli

 

 

Oliver Branaschky

In case of landing altitude above 8000fts there are some crew actions needed depending on flight time.

If flight time is supposed to be less than 60 minutes it is correct to set the correct landing altitude, the controller will set that cabin altitude and mantain it for the entire flight (in this case 13500fts wich is too high)

If the flight is longer than 60 minutes the crew will enter 6000fts (during preflight), around 20 minutes before landing the pilots will enter the landing altitude so the cabin pressure controller will schedule a correct cabin climb until destination.

so should i set lower alt the the real airport's alt?

The only way to get the warning off is to cut out in these conditions. However I think is better to fly with an higher cabin pressure.

 

so should i set lower alt the the real airport's alt?

yes if the flight is long

not if it is short flight