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A321 explosion at Mogadishu

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A321 explosion at Mogadishu

Old 5th Feb 2016, 12:03
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Wageslave - we've seen so many accidents recently when trained crews haven't been able to handle ANY problems and a lot of people have been killed

Whilst the crew here played it by the book -as they should have done - I still think how easy it would have been to panic and add another set of deaths to the stats

Capt Sullenberger and his crew only did what they should of done when they ditched and were (rightly) lauded - should be similar here
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Old 5th Feb 2016, 12:34
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There is procedure in the QRH for loss of pressurisation , & a note to take into account structural damage. There is also a procedure for double engine flameout, and indeed for ditching.

Nonetheless, it is stretching a point to compare the Capt here (who appears to have done a professional job ) with what Sully achieved, wouldn't you agree ?
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Old 5th Feb 2016, 12:56
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Originally Posted by Wageslave View Post
It seems that there are people here who appear not to know or understand what "explosive decompression" is. There bizarrely seems to be a view that it somehow is or results in an explosion or forced dynamic disintegration of the airframe. Quite how this sort of misunderstanding comes about is a bit of a puzzle.

Explosive decompression merely refers to the speed of a decompression. A small-ish hole like this one would not result in explosive decompression, the air would exit over a period of a second or few with a woosh. If a door blew out it might be all but instantaneous and thus deemed "explosive". This has no effect in itself on the airframe - the damage that caused it is the dangerous event.

Of course it is arguable that delta 8psi in the cruise might momentarily exacerbate the bomb damage while it exhausts but it would be tiny compared to the effects of slipstream.

Explosive decompression that results in differential pressure in places not designed to take it (one or two events have distorted the cabin floor resulting in jammed controls, for instance) can cause horrendous problems, but is still nothing to do with an explosion!

I'm chuckling at a mental picture of cabin crew coolly assessing the weight of each pax and directing them to particular zones while feeding the figures back to someone in the galley who is carefully preparing a dropline load-sheet and correcting errant pax positions. Still, it could have happened, I suppose. Probably weren't enough pax on board to have had much effect this time but it's a consideration for the future if everyone flees an event to one end of the aircraft.
I daresay it was more a case of "those at the front cried forward, and those at the rear cried back!"
(with apologies to McCaulay.)

btw, I'm not saying the cc didn't do a good job of keeping cool, I'm not sure we know or whether it affected the outcome.
I disagree with you here. Firstly, the size of the hole and its instantaneous creation would have lead to an explosive decompression by any measure. Second, the reports of "smoke" throughout the cabin and flight deck indicate fogging from the pressure drop; yes,smoke from the explosive is also likely in part of the cabin, but not in the flight deck. A depressurisation fast enough to cause fogging is certainly enough to qualify as explosive. Explosive decompression does not mean that the whole airframe explodes.
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Old 5th Feb 2016, 13:05
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Capt Sullenberger and his crew only did what they should of done when they ditched and were (rightly) lauded - should be similar here
Totally agree. Also, don't forget the cabin crew who kept their acts together in view of too much direct sunlight inside the cabin.
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Old 5th Feb 2016, 14:19
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Explosive Decompression

I have no problem with describing such an event based on rate of change as perceived by a person (boom, fogging, burst ear drums etc.)

At the aircraft structural level it needs differentials in pressure acting over an area per unit of time (blow down rate).

Some notable events have happened in the past with pressure differential across cabin floors occurring fast enough that pressure relief design features couldn't keep up, thus a cascading of effects.
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Old 5th Feb 2016, 14:58
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Originally Posted by Aluminium shuffler View Post
A depressurisation fast enough to cause fogging is certainly enough to qualify as explosive.
Not so. You get fog in a decompression chamber with very gentle decompression.

I'd have thought that to be "explosive" a decompression must be all but instantaneous which I doubt this one was, even though it would have been pretty quick.
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Old 5th Feb 2016, 15:01
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B""B or iPad.

I suppose someone has investigated the trace elements of this explosion, to rule out other possible causes. Such as iPad battery failure, or atomic powered Heart Pace-Maker failure.


Has there been any official report yet of the nature of the device?
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Old 5th Feb 2016, 15:06
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May be it was normal landing afterwards but it is possible to screw up even normal things after a traumatic event. That they didn't, deserves a pat. Even Sullenberger dropped his speed well below VLS leading to high impact touch down with lot of damage to the aircraft but he saved the lives in an extraordinary situation by a correct decision so deserved all the kudos.

Last edited by vilas; 5th Feb 2016 at 17:26.
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Old 5th Feb 2016, 15:22
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Unhappy Groooan Explosive decompression

would have lead to an explosive decompression by any measure.
Puuuhllleeese !- It is a shame that the vast media types have picked up the term explosive decompression for years - **probably** based on the Comet disasters.

If one simply checks with wiki or a few other sites and definitions, it comes down to :

A) Explosive decompression is when the pressure drops so fast that the lungs cannot exhale fast enough to equalize the pressure, causing severe damage to organs, etc- and often death ( the time involved is much less than 1 second depending on total pressure differential )

B) Other forms/definitions for rapid decompression ( talking airplanes here - not diving ) usually involve times more than a second or two. Not comfortable, but not deadly in themselves.

IMO for this case and most cases involving puncture or loss of a skin panel or two the term RAPID really applies ( again ignoring the explosive cause )

Of course the press prefers the term explosive for even a window failure or even a airconditioning duct failure allowing a SLOW or RAPID loss of pressure
And the public has visions of a balloon bursting with thousands of pieces like confetti . .


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Old 5th Feb 2016, 16:19
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WSJ says explosive residue found

Originally Posted by phiggsbroadband
Has there been any official report yet of the nature of the device?
Any official report is likely in the future, but the Wall Street Journal today posted an article asserting that "a Western diplomat, said the investigators had found TNT residue on the remains of the man"

WSJ article

Allowing for some corruption of detail as this got passed along, I, personally, think it likely that someone really has found residue of some type of expected explosive on the deceased's remains, but somewhat doubt it was exactly TNT, which would be a bit surprising in this application.

WSJ, which actually runs pretty capable news gathering, and is pretty careful about accuracy (whatever you think of the politics of the editorial page and the other practices of the owner) is definitely taking the stance that people close to the investigation think it was a bomb (as in an intentional one--not some sort of laptop battery brewup).

So do I.
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Old 5th Feb 2016, 16:22
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As a layperson

It's interesting to me to contrast this to the Metrojet incident, where the plane was completely destroyed by (per the Russians) a bomb which I thought was placed in a soda can....

I realize placement of the device is critical, but perhaps this shows just how critical?
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Old 5th Feb 2016, 16:43
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SLF chipping in here ....

To me it seems remarkably lucky that the individual believed to be responsible for this was allocated the seat they were. Anything further forward and debris from the explosion may have entered no.2 engine and/or impacted the control surfaces of the wing, anywhere towards the rear and again debris may have damaged/taken out the horizontal stabilizer. Certainly could have been a lot worse.
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Old 5th Feb 2016, 17:03
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There is also a procedure for double engine flameout, and indeed for ditching.
True, there is a procedure for double engine flameout, and there is a procedure for ditching. But there is no procedure that emphasises the particular difficulty of ditching with both engines flamed out, that would have been useful for captain Sullenberger.
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Old 5th Feb 2016, 17:29
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particular difficulty of ditching with both engines flamed out,
The normal case, I would have guessed; perhaps one flamed out and the other producing insufficient thrust to stay airborne, but otherwise why ditch with only one engine inoperative? That could make all the stuff about ETOPS a bit of a waste of time.

Sorry, just a thought, back to the thread.
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Old 5th Feb 2016, 17:38
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True, there is a procedure for double engine flameout, and there is a procedure for ditching. But there is no procedure that emphasises the particular difficulty of ditching with both engines flamed out, that would have been useful for captain Sullenberger.






What's the "particular difficulty" of ditching with both engines flamed out that experienced pilots wouldn't be aware of?


And thirty plus years in the business and the manuals have text about consideration of water ditching.
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Old 5th Feb 2016, 20:06
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What's the "particular difficulty" of ditching with both engines flamed out that experienced pilots wouldn't be aware of?
The steep approach angle and high rate of descent requires an increased steady approach speed to permit a flare to zero rate of descent, because the speed bleeds off rapidly in the flare. You are not implying that captain Sullenberger was inexperienced, are you?

Vilas got it right.
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Old 5th Feb 2016, 21:11
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"What's the "particular difficulty" of ditching with both engines flamed out that experienced pilots wouldn't be aware of? "


Oh nothing really. . .you take off from a hard surfaced runway in a commercial twin jet & suddenly find yourself the pilot of a 60tonne plus seaplane over a Metropolitan area . . . piece of cake


"professional pilots" rumour network, Yeah right
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Old 5th Feb 2016, 21:24
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Explosive decompression and "lung damage"

One needs to be careful when consulting with internet references about aeromedical definitions such as explosive decompression. As a flight surgeon I was taught it simply meant decompression of an aircraft which takes less than 0.5 seconds. That is considered by most authorities to be “explosive”.

In a series of 184 explosive decompressions in US Navy aircraft, there was only one case of a pneumothorax (collapsed lung). Airliners have a much larger cabin volume and the risk of a pneumothorax during explosive decompression is even lower. I cannot find a case of a civilian airliner decompression survivor with a pneumothorax in the medical literature since 1972. There is a risk, especially as some people are already prone to pneumothorax at sea level, but it must be a rare event in airliner decompressions.

If you elect to take altitude chamber training, which I highly recommend, you will be exposed to an true explosive decompression without your mask at an altitude of 25,000 feet. You'll see all the stigmata of explosive decompression and your lungs will not explode, money-back guaranteed. They could demonstrate it at higher altitudes, but there's a chance you may not get your mask back on fast enough.

Avoid the burrito especialle and beer for supper the night before - that was a mistake I made once.
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Old 5th Feb 2016, 22:07
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As a flight surgeon I was taught it simply meant decompression of an aircraft which takes less than 0.5 seconds. That is considered by most authorities to be “explosive”.
Agreed- my point is that for the case(s) in point, and IMO the decompression time was most likely LONGER than .5 seconds simply due to the area of the " hole" and the volume of air to be removed.

The flight data recorders may well have picked up the actual times involved.

The hawaii convertible 737 could well have been near or less than the .5 seconds due to the VERY large areas involved.
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Old 5th Feb 2016, 23:30
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Conso,
groooan - and what difference would it have made except for some very uncomfortable passengers and possibly an injury nor two ? Why do you think a higher altitude with a higher delta p ( inside to outside ) would have done more structural damage ?
IMO - A higher delta p would/may open a slightly larger hole to the nearest circumferential/stringer in the skin.
Of course higher delta pressure or larger breach hole would have induce more structural damage. You need to understand the dynamics of decompression. It is based on delta pressure differentials, volumes, initial breach area and venting areas between opened volume vs. adjacent volumes (between cabin vs. sub-floor, lavatories, cockpit etc). The danger of structural damage is not at blown window but at junctions between floor, cross beams and frames, also at bulkheads upper attachments to stringers. Higher delta pressure will produce more stress at enclosed volumes vs cabin.
At 14000 ft the delta pressure was not strong enough to fail the overbin latches. For example, the Mythbusters decompression opened all overbins, for a smaller breach hole (but at 33000 ft)
Video at 2:54
https://youtu.be/Fi1_1l7M8FA?t=174
The flight data recorders may well have picked up the actual times involved.
Nope
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