A320...Pack 1+2 Fault (Inflight)

[kuwait340]

Hello...

assuming that you are in the cruising altitude, say at FL330..and your cabin altitude is ~5500 feet.

suddenly ! ....you lost your Pack 1+2.....

the ECAM will present the actions for that failure...and when it comes to "descent to FL100/MEA..."
1-do you have to initiate emergency descent or a normal descent ?

i would say...normal descent with R.O.D of ~2500-3000 fpm , because the oxy masks will drop at 14000 cabin alt.and you are away from this alt by 8500 feet(14000 - 5500 ) ...and you need to lose (33000-14000) = 19000 feet ...so 19000/2500fpm= 7.6 mins ...assuming the cabin climb rate is 1000 fpm...ofcourse this is all assumptions.
But...if you are FL390 with cabin alt of 8000...i would say you have to initiate emergency descent.

2-will the cabin climb rapidly/slowly ?
i think it will climb slowly...but at the end of the day...it is not as bad as a rapid decompression.
3-at what rate you think the cabin climb rate will be (fpm) ?
i think it will vary between new and old aircraft...

any suggestions...ideas to share :)

thanks in advance

[tarik123]

if Iam not mistaken, if you are at 39000ft and lose the packs, the
time for the cabin to reach 14000ft should be not be less than 8 minutes.

So I would say at 35000ft to reach 10000ft you need around 3200ft/min

[WaterMeths]

I think this is a great example of a fault which highlights the need to sit on ones hands first before reacting.

An expedicious descent would probably be wise under the circumstances, whereas a full emergency descent - setting off all those TCAS RA's on the way down is perhaps overkill.

[Down Three Greens]

From air test experience on the A320, with both packs off and the outflow valve closed, the cabin altitude will climb at around 300ftmin.

DTG

[FlexibleResponse]

If you have a pack 1+2 fault, it will be no longer possible to pressurise the aircraft.

The residual cabin pressure will leak at a slow to very fast rate depending on factors over which you have no knowledge or control ...namely, the serviceability of the seals on the outflow valves, cargo doors, passenger doors, etc.

Depending on your passenger complement, age group and health status, it is likely that at least some will be stressed merely by the fact that the aircraft cabin in normal cruise is x number of thousand feet above sea level pressure. If the cabin climbs above 10,000 and certainly above 15,000 feet, some passengers will face very serious health consequences if not the imminent threat of death. This is your responsibility and you may face a Court of Law and gaol if you get it wrong.

If you have a pack 1+2 fault which cannot be remedied immediately, you have no choice but initiate an emergency descent using the approved Airbus procedures.

If after you descend and level the aircraft at a safe level of 10,000 feet or MEA, and you are then able to re-establish normal function to the pressurisation syystem, it is ever so simple to climb back to cruising altitude and continue the flight to destination.

But, if you stuff around and dawdle in the descent, thereby causing the pax oxygen system to deploy at 14,000 feet, you now have NO choice but continue the flight at a maximum of 10,000 feet or MEA due to the lack of pax oxygen (already used), regardless of pressurisation system rectification.

As always, if in doubt, FOLLOW the APPROVED AIRBUS PROCEDURES!

[sarah737]

And Airbus sasys: descent to 10000/MEA. No mention at all about emergency descent.

[TyroPicard]

My FCOM 3 says
PACK 1+2 FAULT ... DESCENT TO FL 100/MEA
whereas in EXCESS CAB ALT it mentions EMER DESCENT
So which is the APPROVED AIRBUS PROCEDURES!

TP

Edit: Darn, too slow!

[Aspen20]

All depends on cabin leak rate. I would personally not tend towards a emer des.

[UP and Down Operator]

A collegue of mine had that exact failure some month back. They were cruising at FL380 when the packs went offline. According to him, they agreed faily swift on initiating a descent but still used a few seconds to evaluate the circumstances first.

They were, cabin rate of climb = 500 ft/min. Time available = x minutes (can't remember what he told me exact), and MSA about 4000ft.

They initiated a normal descent (in open descent) with a turn off the airway, declared a Mayday to clear the way ahead and monitored the situation.
Cabin never came higher than 9000 ft and no masks were deployed. Pax had no complaints as it was not uncomfortable and cabin crew managed to control their trolleys with no danger for themselves and pax. Mayday cancelled again and they diverted with no stress.

Seems to me to be a job well done, and there were no stress as they used the time needed (but not more than that) to evaluate factors. The A/C was fairly new, so that might have been one reason why the cabin climb was kept low.

[Viper2]

Depending on your passenger complement, age group and health status, it is likely that at least some will be stressed merely by the fact that the aircraft cabin in normal cruise is x number of thousand feet above sea level pressure. If the cabin climbs above 10,000 and certainly above 15,000 feet, some passengers will face very serious health consequences if not the imminent threat of death. This is your responsibility and you may face a Court of Law and gaol if you get it wrong.


I think it is very unlikely that people will face very serious health consequences if they are being exposed to a cabin altitude above 10000 ft for a short time. If this was the case aircraft designers would make the aircraft to drop the masks as soon as the cabin altitude would be over 10000ft. Furthermore ... in case of a rapid decompression where the cabin altitude would reach the cruise altitude this would result in many serious health problems if I understand your statement. I have not seen so many incident reports stating this issue....

In my opinion, with this scenario I agree with many posts made before. Descend to FL100/MEA. Exactly like airbus states in the procedures. No word about emergency descent. Descent ... do not delay ... and maybe expedite a little bit (to avoid the rubber jungle in the back of the aircraft off course).

The only time when the term "emergency descent" comes into my mind is when ATC is not very co-operative. If in this case your PAN call did not solve the problem you might consider using this term to get immediate descent clearance...

Just some thoughts....

[threemiles]

I believe MEA is not the right phrase for this, as this determines the airspace related lowest altitude, which can be as high as FL250 or so. Isn't MSA the right phrase?

[Max Angle]

cabin rate of climb = 500 ft/min. Don't try the same in a 737, it leaks like a sieve, at least the 3/4/500 Series did.

[iaf_22]

MSA is only 25 Nm around a navaid... AND this information is not easily reachable in cruise (it's on instrument approach plates..)
Enroute, you would use the Grid MORA (on the Jeppesen Enroute charts) to evaluate how low you can descent.