Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Emergency Descent - 36000'

Tech Log The very best in practical technical discussion on the web

Emergency Descent - 36000'

Old 18th Jun 2013, 03:14
  #61 (permalink)  
 
Join Date: Sep 2008
Location: 41S174E
Age: 52
Posts: 2,767
My take on Rat's original question was more "let's talk about it and see if there can be a shift in emphasis" on Emergency Descents rather than getting into minutiae about ToUC, colds, skydivers etc etc.
That's what I was doing, I think it's a very valid point Rat has brought up so was trying to get to the nuts and bolts of where the greatest risk lies.
Weeeell, the lights may have been on but I'd doubt anyone was home.
For sure, that's why I prefaced the comment with " for interests sake".
Most pilots I have chatted to about the accident are surprised to learn that the pax were still alive. It's interesting in my book, I meant nothing more.
Whoa! No-one is talking about cruising at 30k for 3 hours!! RAT asked why we scream straight down to 10k rather than, say, 14k and ease off.
I understand that and addressed Rats main point clearly. As I said above, the reference to Helios was purely a point of interest. I'll try to be more clear with my wording in the future.
framer is offline  
Old 18th Jun 2013, 03:27
  #62 (permalink)  
 
Join Date: Sep 2008
Location: 41S174E
Age: 52
Posts: 2,767
This is the crux of Rat's point;
So why are we encouraged to max it down to 10,000? I repeat, in real life ear drums have been burst by just such action. A max descent to 14,000' can be argued for, but surely a more relaxed 1500fpm to 12,000' and then 1000fpm to 10,000' will be more than adequate.
I think it's worthwhile to examine it and take it slightly beyond being just an opinion so I asked
where does the the greatest risk lie?
and
Does anyone have any examples or stats on burst eardrums during emergency descents?
in one post. I didn't get an answer so in my next post I wrote
I just thought it worth while seeing if there were any examples in the real world of the eardrum burst.
and
Of the examples of burst eardrums, how many burst as the air escaped their sinuses as opposed to bursting in the last 4000ft of descent as the thicker air entered their sinuses?
The questions and statements above that I made haven't really been addressed. That's fine, I was just hoping to take it beyond individual opinions and preferences and get some more detailed information so that we could debate based on that.
I'm still keen to do that because, like I said, I think Rat has raised an interesting subject.
framer is offline  
Old 18th Jun 2013, 04:09
  #63 (permalink)  
 
Join Date: Aug 2005
Location: fl
Posts: 2,561
The B737 take off warning horn being used as a cabin altitude high warning is confusing. I had it happen to me on an idle descent with one pack inop and an equipment cooling valve stuck open. It took a few seconds to realize the dual purpose since we have all heard the take off warning when advancing throttles to taxi with flaps up but never for the alt. warning. We advanced the power and put the second pack on to get everything back to normal. The Athens flight I am sure had the same problem identifying what the warning was for.
bubbers44 is offline  
Old 18th Jun 2013, 07:11
  #64 (permalink)  
Per Ardua ad Astraeus
 
Join Date: Mar 2000
Location: UK
Posts: 18,584
deltahotel - "Any time above 25000' cabin alt is bad,". I do remember North Luffenham etc, and I did actually have the odd 'decompression pain' in my joints after several long (boring) un-press details at 30k in the JP3/4.

I think you have summed it (and, I think, Rat's point) up well. I have always thought the sim exercise was just a synthetic 'mad scramble' (though useful for initial drills etc), and I had often wondered about how I would have handled such with bomb damage. There one would surely accept pax and c/crew oxy problems for the sake of keeping the aircraft in as few pieces as possible?

framer - all noted and understood, but I do think we need to look at the 'bigger picture' and ask why we always just 'scream down' rather than worry about eardrums and the like? Every foot lost from cruise altitude is a bonus in oxy terms. The question is, of course, now complicated by the higher cruise levels in use and there does remain the need to vacate those as expeditiously as possible. In real terms, below about 20k, the panic is over. Having been up to 18k 'without', I know the effects of hypoxia will be there, but one can still function. There is a risk that those with 'degraded' body oxy functions might lose consciousness but I suspect that would be all they suffered for the short time taken going lower. I assume Concorde did not have 'pressurised' masks for pax, so it would have been an interesting scenario indeed from around 50k+.
BOAC is offline  
Old 18th Jun 2013, 09:01
  #65 (permalink)  
 
Join Date: Mar 2007
Location: Another Planet.
Posts: 557
How many companies ask one to demo this in the sim, assuming the other crewmember is trousers-down in the toilet when the explosive event happens, NO PUN INTENDED!

Worth thinking how we'd do all the bits solo, assuming mask on etc?

One day it may happen..............................?!
BARKINGMAD is offline  
Old 18th Jun 2013, 09:02
  #66 (permalink)  
 
Join Date: Sep 2008
Location: 41S174E
Age: 52
Posts: 2,767
There is a risk that those with 'degraded' body oxy functions might lose consciousness but I suspect that would be all they suffered for the short time taken going lower.
I agree.
What I am wanting to do is weigh that risk against the risk of other injuries to the passengers ( burst eardrum was the example given) and then decide now, from the comfort of my lounge room chair, whether or not to modify how I plan to fly an emergency descent due depressurisation.
The unconscious pax ( and associated workload for cabin crew) that you mentioned above would be hard to justify if there is no real world examples of injuries to pax caused by maintaining a high ROD between 14,0000ft and 10,000ft.
Righto, time to go to work.
Hope you guys are having a nice day up north.
framer is offline  
Old 18th Jun 2013, 09:39
  #67 (permalink)  
Per Ardua ad Astraeus
 
Join Date: Mar 2000
Location: UK
Posts: 18,584
Originally Posted by framer
Righto, time to go to work.
- ugh! Night flight..............

I think for 'personal career safety' we would need a sea change at regulatory level to "modify how I plan to fly an emergency descent due depressurisation.". It will be a brave man/woman who demonstrates a 'non-standard box ticking' in the sim

Thanks for the wishes. Summer may just have arrived 'oop north'. Hope the duty went well.

Good topic, Rat!
BOAC is offline  
Old 18th Jun 2013, 10:23
  #68 (permalink)  
 
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,510
Quote : " surprised no one has raised the 'turn off the airway' chestnut.... "

Don't ignore RA - the other guy won't and you get no more points (and therefore no more prizes) for an immaculate emergency descent which writes off two ac.

Which is exactly why, as has been mentioned here, and extra 20secs to let ATC join the team and be a major player, is a good idea. They may well have a nice escape route planned for you as soon as they hear MAYDAY. It might not be a straight ahead or a turn off, but a series of zig zags while they clear other a/c out of the way. In the sim it is always just straight ahead or 45 degrees off, in a straight line and plunge to 10,000'. Not much of a learning exercise.

As for the RA, that is why Eurocontrol advocate TA only. It should not happen.

I think we've done it to termination and the point now is that the old method might need reviewing. But, again, until a major incident I doubt it will happen; there is no incentive.
RAT 5 is offline  
Old 18th Jun 2013, 23:00
  #69 (permalink)  
 
Join Date: Jan 2012
Location: Not far from the edge of the Milky Way Galaxy in the Orion Arm.
Posts: 510
" surprised no one has raised the 'turn off the airway' chestnut.... "
at 90 degrees to the airway?
Natstrackalpha is offline  
Old 19th Jun 2013, 00:11
  #70 (permalink)  
 
Join Date: Mar 2002
Location: Seat 0A
Posts: 7,769
at 90 degrees to the airway?
Not necessary. With GPS accuracy, all that is needed is "select" a 45° heading change (helps get the nose down too) then immediately back to parallel the magenta line. Nicely offset from opposite direction traffic (if it is a two-way airway). IOW, quick-setup SLOP.
Capn Bloggs is offline  
Old 4th Jul 2013, 16:35
  #71 (permalink)  
 
Join Date: Feb 2010
Location: WORLD
Posts: 101
As you say, at the beginning post nº 1, it was not an explosive depressurization but readings in cockpit made think about a problem in relation to pressurization. In my opinion... and some QRH says...First of all, Pilots should have tried a manual control to keep the presurization before carrying out an emeregency descent.
You can control and adjust the presurization manually. After that, controling in manual mode you can consider leave FL 360 to FL 130 bearing in mind your fuel and weather conditions for the following miles to destination. However, I wouldn´t leave FL360 if I can adjust the presurization system, manually.

Last edited by NEWYEAR; 6th Jul 2013 at 11:43.
NEWYEAR is offline  
Old 5th Jul 2013, 19:25
  #72 (permalink)  
 
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,510
Of course: a pressurisation problem does not mean an E.D. An RTO does not mean a Pax Evac. Same philosophy. Simulatoritis. It can often be a bad thing.

Last edited by RAT 5; 5th Jul 2013 at 19:26.
RAT 5 is offline  
Old 7th Jul 2013, 16:15
  #73 (permalink)  
 
Join Date: Jan 2012
Location: Not far from the edge of the Milky Way Galaxy in the Orion Arm.
Posts: 510
RAT 5

I think we've done it to termination and the point now is that the old method might need reviewing. But, again, until a major incident I doubt it will happen; there is no incentive.
. .there is. Collectively you have all done a good job here.
The review you mention is in place and a `work` package is being put together by ICAO and all associated xAAs. The resultant factor should be 2014 - which is better than nothing, I suppose.
Natstrackalpha is offline  
Old 22nd Jul 2013, 23:25
  #74 (permalink)  
 
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,510
Adding another element to this discussion: firstly I am pleased a review is under way, I seek further opinions on this question.My QRH instructs me to descend to "10,000ft or MSA which-ever is higher." It is emphasised that crew O2 is necessary above 10,000'. (not for the expendable pax). I ask, why restrict your descent to 10,000'? If the MSA is a very common <5000' why not continue to a lower level where O2 is more abundant? Surely that's better?[LIST]I was doing the 3 year tick in the box and I descended to FL80, with TL 70 and MSA 2500'. The cabin was <10,000' so we could remove O2 masks. We were in controlled airspace above TL, so I surmised that ATC would require us to fly in 1013 for a/c separation. To fly on QNH would create a threat of RA's etc.
No! I was told this was wrong as the QRH said 10,000' of MSA 'which ever was HIGHER'; AND it must be on QNH.

Please, an ATCO, please tell me you would not welcome us flying around in your airway on QNH. Please tell me I'm not crazy and I can have my sanity back. Please tell me this is QRH PC gone mad.
RAT 5 is offline  
Old 23rd Jul 2013, 23:12
  #75 (permalink)  
 
Join Date: Jan 2005
Location: In t'sky
Posts: 576
If I can add my two-penneth as well..

...Why 10,000 feet? In the US and areas where the TL is 18,000 as standard I can understand, but until Europe is brought in line with other countries why don't we descend to FL100, or FL90? I imagine the selection of FL90, especially in the UK, is more helpful to ATC rather than flying around at some equivalent to FL93 and screwing up their RVSM separation. Even if the QNH is 980 you are protected at FL90 from reaching a cab alt above 10,000"?

Just something i've been mulling over..

EDIT: Just realised RAT 5 has written a similiar point to mine - ATC input would be interesting.

Last edited by MrHorgy; 23rd Jul 2013 at 23:14.
MrHorgy is offline  
Old 24th Jul 2013, 08:50
  #76 (permalink)  
 
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,510
The 18,000' TA in USA was my first solution to the 10,000' command in QRH. In USA it does not cause a problem. When I tried, via my training dept., to voice this question to Boeing and XAA's it was met with deaf ears. So there we are in the sim training something that is unrealistic and XAA's don't seem to care, neither did HOT. To be told it was WRONG to descend to FL80 was the last straw and confirmation that the loonies had taken over the place.
The USA might thing it rules the world. but not outside US airspace.
RAT 5 is offline  
Old 24th Jul 2013, 09:06
  #77 (permalink)  
 
Join Date: Sep 2010
Location: England
Posts: 1,955
I wonder if its just something as simple as maximising range once you've descending to a survivable altitude. Of course that doesn't matter over the middle of Europe but, mid Atlantic it might make a difference. Of course, if that's the case why not higher.

Rat5, I wonder how you're instructor expected you to land if you weren't supposed to go below FL100!
Lord Spandex Masher is offline  
Old 24th Jul 2013, 09:14
  #78 (permalink)  
Psychophysiological entity
 
Join Date: Jun 2001
Location: Tweet Rob_Benham Famous author. Well, slightly famous.
Age: 80
Posts: 4,697
Being peppered with bits of molten glass encourages one to turn off windshield heating. Seeing splits spreading through the glass gives a broad spectrum of encouragements.

Last one for me was 34k over Zagreb one night. 15,000' was as far as we could bomb down without real navigation. With the glass breaking up the VSI was against the bottom stop in the time it took to make panicky noises at the passengers.
Loose rivets is offline  
Old 24th Jul 2013, 09:50
  #79 (permalink)  
 
Join Date: Feb 2010
Location: WORLD
Posts: 101
Obviously, Oxygen (O2) is important.
Some QRHs use MEA instead of 10.000 or MSA. Others...consider at least FL130 "as a the top" because it is the FL or altitude in which you can avoid an automatic deployed of masks and also be able to breath and save fuel for a while...
In adition to this, crew must contact to ATC. Notify ATC and request whatever you need.
NEWYEAR is offline  
Old 24th Jul 2013, 09:59
  #80 (permalink)  
 
Join Date: Feb 2001
Location: The Winchester
Posts: 5,364
Some QRHs use MEA instead of 10.000 or MSA. Others...consider at least FL130 "as a the top" because it is the FL or altitude in which you can avoid an automatic deployed of masks and also be able to breath and save fuel for a while...
...And just to add to the mix on some types it's 15000' or MSA, whichever higher....

As LSM has said:

its just something as simple as maximising range once you've descending to a survivable altitude. Of course that doesn't matter over the middle of Europe but, mid Atlantic it might make a difference
wiggy is online now  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.