SQ A380 emergency landing in Baku due to low cabin pressure
Controversial, moi?
If so what about a PA announcement or even some sort of emergency message displayed on all in flight entertainment screens ?
There is an expression in aviation for priorities - 'Aviate, Navigate, Communicate' in that order. Passengers not immediately being told what is happening is not going to kill them. A PA can wait until a suitable moment, carrying out an emergency descent is not a suitable moment.
One of things not much thought about with the A380, great aeroplane that it is, is the lack of airports able to handle it. A large aircraft diversion stretches any airport not accustomed to handling one so an A380 in BAKU is a headache for the airport, airline and passengers.
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One of things not much thought about with the A380, great aeroplane that it is, is the lack of airports able to handle it. A large aircraft diversion stretches any airport not accustomed to handling one so an A380 in BAKU is a headache for the airport, airline and passengers.
(sorry, is only meant to make the super-jockeys jump ..... )
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4 or 2 what's the big D they were all working,would be great to find some place more suitable but Baku is the only in the vicinity,Turkey few hours away as well as Emirates
how big a leak is needed?
An element of this incident that puzzles this non-pilot is the relationship between the probable scale of the door-seal leak and depressurization.
I have the impression that in normal conditions the air paks provide considerable excess flow which only fails to over-pressurize the aircraft by leaving through a large outflow valve.
Presumably a fault in a door seal alone would need to leak more than the normal discharge of the outflow valve in that state of flight even to cause a reduction in cabin pressure. Of course if there were other abnormal leaks, or the outflow valve or controls suffered a simultaneous fault which prevented it from closing sufficiently, then a door seal leak could push an already degraded operating point past the edge.
Too much speculation--so I'll switch to questions.
Do people here have actual experience of a door-seal leak alone (which I understand to be common) causing a cabin pressure departure from allowed limits in an otherwise fully healthy aircraft?
Approximately what is the normal outflow air flow through the valve at cruise altitude?
I have the impression that in normal conditions the air paks provide considerable excess flow which only fails to over-pressurize the aircraft by leaving through a large outflow valve.
Presumably a fault in a door seal alone would need to leak more than the normal discharge of the outflow valve in that state of flight even to cause a reduction in cabin pressure. Of course if there were other abnormal leaks, or the outflow valve or controls suffered a simultaneous fault which prevented it from closing sufficiently, then a door seal leak could push an already degraded operating point past the edge.
Too much speculation--so I'll switch to questions.
Do people here have actual experience of a door-seal leak alone (which I understand to be common) causing a cabin pressure departure from allowed limits in an otherwise fully healthy aircraft?
Approximately what is the normal outflow air flow through the valve at cruise altitude?
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As an Airbus (not 380) Capt, your:
is about spot on 
A leaky door seal is hardly rare, and just makes an annoying noise. I think Packs / Pressurisation are designed to cope with 1 (or more?) windows blown out.
We'll see, seems to me pretty standard decompression, flown correctly, land. It is also pretty standard Pax are frightened / alarmed / think they were going to die *...
NoD
PS * and they are unlikely to be "reassured" by the Captain trying to make a PA whilst wearing an Oxygen mask
Presumably a fault in a door seal alone would need to leak more than the normal discharge of the outflow valve in that state of flight even to cause a reduction in cabin pressure. Of course if there were other abnormal leaks, or the outflow valve or controls suffered a simultaneous fault which prevented it from closing sufficiently, then a door seal leak could push an already degraded operating point past the edge
A leaky door seal is hardly rare, and just makes an annoying noise. I think Packs / Pressurisation are designed to cope with 1 (or more?) windows blown out.We'll see, seems to me pretty standard decompression, flown correctly, land. It is also pretty standard Pax are frightened / alarmed / think they were going to die *...
NoD
PS * and they are unlikely to be "reassured" by the Captain trying to make a PA whilst wearing an Oxygen mask
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I'm with you archae86 . I don't think a leak in a door would be, by itself, enough reason to depressurize an A380 to the point of deploying oxygen masks. There has to be something else, that was not disclosed yet.
When a "slow" depressurization occurs, pilots get an ECAM advisory indication and, if incapable of solving the problem, they may start the emergency descent in order to reach the cabin altitude before oxygen masks deploy.
There are, of course, other reasons to deploy the masks even when reaching cabin altitude "in time". Minimum obstacle or of route altitudes, come to mind.
As usual, lets wait and see...
When a "slow" depressurization occurs, pilots get an ECAM advisory indication and, if incapable of solving the problem, they may start the emergency descent in order to reach the cabin altitude before oxygen masks deploy.
There are, of course, other reasons to deploy the masks even when reaching cabin altitude "in time". Minimum obstacle or of route altitudes, come to mind.
As usual, lets wait and see...
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We'll see, seems to me pretty standard decompression...
An aircraft door is not designed to leak nor should (in these days) an aircraft be knowingly flown with a reported door leak problem. Never mind the quotes about 'noise being heard' and 'doors being checked' the photographic evidence alone shows there was a major problem with the door.
I'm sure the apparently craggy old long-timers will talk about stuffing wet rags in the holes and nicotine stains on the fuselage etc but that was then, this is now and it's unacceptable.
OLD RED DAMASK
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An aircraft door is not designed to leak nor should (in these days) an aircraft be knowingly flown with a reported door leak problem. Never mind the quotes about 'noise being heard' and 'doors being checked' the photographic evidence alone shows there was a major problem with the door.
I'm sure the apparently craggy old long-timers will talk about stuffing wet rags in the holes and nicotine stains on the fuselage etc but that was then, this is now and it's unacceptable.
I'm sure the apparently craggy old long-timers will talk about stuffing wet rags in the holes and nicotine stains on the fuselage etc but that was then, this is now and it's unacceptable.
Get a life for God's sake and stop whinging!! You make all us SLF's sound paranoid.
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Quote:
We'll see, seems to me pretty standard decompression...
If I may respectfully beg to differ...
We'll see, seems to me pretty standard decompression...
If I may respectfully beg to differ...
That to me is "pretty standard". There is no "pretty standard" cause, and is not terrible relevant to the crew or their actions at the time - you deal with the symptoms.
nor should (in these days) an aircraft be knowingly flown with a reported door leak problem
There is, to the best of my knowledge, no way a "rapid decompression" will happen solely due to a faulty door seal. It would take more fundamental door problem... Whilst not want you might want to hear, but we tend to "carry leaky" door seals until a convenient time to repair them - and often after the door is opened / closed, the problem goes away.
NoD
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When I refer to "standard decompression" I mean the actions of the crew / perceptions of the Pax. Steep "terrifying" dive, shortly after it started masks came down (shows crew ahead of the game), dove ~20000'+, no PA, Pax all frightened.
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the photographic evidence alone shows there was a major problem with the door.
Have you ever flown in an AA 757 from Man to ORD in the emergency exit row? I have many times and all their doors are leaky. To the extent they made up "hot" water bottles as the interior walls were that cold. Old BA 747's the same.
An aircraft door is not designed to leak nor should (in these days) an aircraft be knowingly flown with a reported door leak problem.
I'm sure the apparently craggy old long-timers will talk about stuffing wet rags in the holes and nicotine stains on the fuselage etc but that was then, this is now and it's unacceptable.
I'm sure the apparently craggy old long-timers will talk about stuffing wet rags in the holes and nicotine stains on the fuselage etc but that was then, this is now and it's unacceptable.
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How long would "decent" ~20000' dive take pls Nigel?
There are 2 descent profiles - 1 if you think there may be structural damage, the other if not. In the latter, it is idle, full speedbrake, as fast as you can go. In the former you are more restrained
Crew and Passengers can survive for a long time on Oxy Masks at cruise altitude, albeit cold. However, the assumption is that some in the cabin will not have listened to the Safety Video, and will not be on oxygen. They have ~15s of consciousness and 3mins to possible brain damage. Very roughly, once below 20K' the brain damage issue has gone. So you can see the priority...
Usual aim is to level at 10K', but terrain may limit that and around Baku is a factor.
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EMER DESC
If I remember correctly the magic sequence after oxy masks on and establish communications is:
TURN/PULL (ALT) - PULL/TURN (HDG) - PULL (SPD).
All kinds of auxiliary tasks by PM of course and second round for both PF and PM.
If I remember correctly then MAN OXY ON is a checklist item (the so-called 'lawyers switch' - you manually deploy oxy masks even if they have been deployed automatically already.
Emergency descent is never initiated by the aircraft. If nothing is done the crew (and pax) would fall unconscious eventually, A/P would maintain FL and everyone would perish while F16 (or MiG 29) pilots watch the aircraft run out of fuel and dive (remember Helios?).
After emergency descent initiation, communication with the Pax goes out of the window as pilots will be busy checking MSA, range at lower level, diversion airports etc.
Job well done by flight deck crew it seems!
A night at Baku airport without water is a survivable event (unlike slow or rapid decompression at FL380 without action being taken by the flight crew).
TURN/PULL (ALT) - PULL/TURN (HDG) - PULL (SPD).
All kinds of auxiliary tasks by PM of course and second round for both PF and PM.
If I remember correctly then MAN OXY ON is a checklist item (the so-called 'lawyers switch' - you manually deploy oxy masks even if they have been deployed automatically already.
Emergency descent is never initiated by the aircraft. If nothing is done the crew (and pax) would fall unconscious eventually, A/P would maintain FL and everyone would perish while F16 (or MiG 29) pilots watch the aircraft run out of fuel and dive (remember Helios?).
After emergency descent initiation, communication with the Pax goes out of the window as pilots will be busy checking MSA, range at lower level, diversion airports etc.
Job well done by flight deck crew it seems!
A night at Baku airport without water is a survivable event (unlike slow or rapid decompression at FL380 without action being taken by the flight crew).
Last edited by uncle_maxwell; 6th Jan 2014 at 16:19.