A320 emergency descent

[captain87]

I'm an Airline Pilot Student who is studying for A320 TR before performing it ...

I'd like to clear up a doubt about a specific procedure to be adupted when a cabin depressurization occurs with an A320 in cruise over the mountains (30.000 ft high) ... provided the CFIT procedures and GPWS operating normally. We suppose that SYS 1 + SYS 2 are INOP and the MAN control of the outflow control valve is fault due to the respective failure of the manual elect motor. So the Oxygen Masks now deployes automatically and ... (since) an emergency descent to 10.000 ft should be started immediately, is it possible to maneuvre the aircraft so close to terrain ? ... if affermative: Should the maximum 750 ft/m rate of descent (for pressurization) be matched anyway ? ...

That's just a doubt that I'm not sure could really happen ...

Thank you and Best Regards

by captain 87

[Empty Cruise]

You don your masks & establish communication - and then try your best to re-establish pressurisation.

If that fails - you communicte the loss of pressure the the cabin crew and make sure the rubber jungle has deployed.

From there on - it's no longer an emergency, but a time-limited scenario. However, the important actors in this stage of the drama - the flightdeck - have a looooooooooong time available before they run out of oxygen. Therefore - chill! Think & then act! Your CC and pax are not going to die on you for the first 10-15 min., so spend 30 seconds calming yourself down.

If you're overflying terrain that high :8 - you have a decompression escape route designed by your company & their performance engineers. So turn onto your escape route and follow the descent restrictions specified therein (it's 10.000 ft or MOCA, btw) while carrying out your "emergency" descent drill, bearing in mind that the real emergency is over and no-one is gonna die, just as long as you don't panic.

Enjoy! ;)

[captain87]

Thank you very much and seasons greatings !

captain87

[SIDSTAR]

It doesn't matter which aircraft type you fly, the basic process is the same. If the pilots don't survive nobody will, so you must first protect yourself (remember the Helios accident?)

You make sure you've got Oxygen masks on and establish crew comms. With O2 flowing you can be reasonably sure that your decision-making capability is normal.

The remainder of the process is easy

- get the aircraft going down,
-establish it's doing what you want it to do (FMA)
- then refine the speed, altitude and heading targets depending on the terrain, whether you have structural damage and ATC instruction.

When you get below MSA/10000 ft consider limiting your V/S to below 500fpm as everyone including yourself will probably have very sore ears or worse.

Cabin crew should sit down in the nearest available (pax) seat and grab the first available mask until the emergency part of the descent is complete. They should then be released to carry out checks on the pax and a/c and report the cabin situation to the commander. Their emergency drills would normally cover this.

[captain87]

:ok: Thank you for your explanation SIDSTAR !

... obviously I already know that all the procedures are the same in case of emergency descent, but I was doubtful about the one I mentioned in this thread. I didn't keep in mind cabin decompression routes that have to be used to ! ... Anyway I am perfectly aware that oxygen allows a good margine in terms of time, but Helios accident was caused by crew unawareness ... so they didn't realize of lack of cabin pressurization due to system failure ...


;) Best Regards,
captain87

[IFixPlanes]

... so they didn't realize of lack of cabin pressurization due to system failure ...
There was no system failure. :=

[captain87]

:rolleyes: Sorry, what happened ? ... I thought there were initially some problems with Equipment cooling System and a Takeoff Conf warning !

It is a failure (or abnormal) ? ... isn't it ?

[IFixPlanes]

Link (http://www.google.de/url?sa=t&ct=res&cd=1&url=http%3A%2F%2Fwww.moi.gov.cy%2Fmoi%2Fpio%2Fpio.nsf%2FAll% 2FF15FBD7320037284C2257204002B6243%2F%24file%2FFINAL%2520REP ORT%25205B-DBY.pdf&ei=hKmAR6ZRir75AtaU-NMP&usg=AFQjCNGGA_9IK8mZewylIuEnTUnap0B9Vw&sig2=b-mIt8ywtL8aKOyFJSiIlA)

Go to page 152 ff. (CONCLUSIONS)

If the link does not work search for "HELIOS AIRWAYS FLIGHT HCY522"

Ingo

[captain87]

:ok: Thank you IfixPlanes
Have a good sunday !

[DesiPilot]

What happened was that the previous crew had reported air leak from the aft door and there was visible condensation on the inside of the aft door. While checking for the pressurisation leak the engineers had put the pressurisation control to manual and after they were finished they forgot to change it over to AUTO. The flight crew also failed to notice the same and rest is history.