Qantas 744 Depressurisation
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Usually Vmo for max performace so your descent speed is at the barber pole
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In remark to the passenger quote
Passengers praised the crew's handling of the incident, but some complained that not all the oxygen masks worked properly.
"The elastic was so old that it had deteriorated. I was trying to get my passport, and every time I got my passport the mask fell off and I started to pass out," architect David Saunders told Fairfax.
Despite the fact that the elastic on the mask was deteriorated, David still had oxygen from what I gather. When one bottle goes, dosn't all the O2, secondly, you would only need to check the aircraft and make sure each oxy mask door was open in the cabin. Wouldnt that be enough to explain if the oxy bottle had failed or not?
Passengers praised the crew's handling of the incident, but some complained that not all the oxygen masks worked properly.
"The elastic was so old that it had deteriorated. I was trying to get my passport, and every time I got my passport the mask fell off and I started to pass out," architect David Saunders told Fairfax.
Despite the fact that the elastic on the mask was deteriorated, David still had oxygen from what I gather. When one bottle goes, dosn't all the O2, secondly, you would only need to check the aircraft and make sure each oxy mask door was open in the cabin. Wouldnt that be enough to explain if the oxy bottle had failed or not?
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To KiloB:
Indeed, like if that piece of structure has been punched out. Like many posters have addressed, an O2 bottle does not just rocket out of an aircraft. There is probably more to the sequence of events which a thorough investigation will reveal.
Also, it is not possible to tell from the pictures how large the initial hole was. I do believe, however, a force large enough to punch out the skin also took out the lapjoint and thus, was part of the initial damage done to the structure. Decompression and aerodynamic forces probably made the hole much larger, ripping away jagged pieces of structure which were fluttering in the disturbed airflow due to the shattered fairing which most likely separated from the aircraft at the time of the structural failure.
Regards,
Green-dot
The 'bent outwards' piece of hull near the top of the picture has a suspiciously even and rounded edge on one side. Almost as if it got in the way of a cylinder going somewhere in a hurry!
Also, it is not possible to tell from the pictures how large the initial hole was. I do believe, however, a force large enough to punch out the skin also took out the lapjoint and thus, was part of the initial damage done to the structure. Decompression and aerodynamic forces probably made the hole much larger, ripping away jagged pieces of structure which were fluttering in the disturbed airflow due to the shattered fairing which most likely separated from the aircraft at the time of the structural failure.
Regards,
Green-dot
Last edited by Green-dot; 27th Jul 2008 at 19:07. Reason: typo
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LapSap,
Having experienced an emergency landing as a passenger (the real thing, including the "brace" position) I think I may have some insight into the behaviour of the passenger who wanted to get his passport. As we were descending I had what later struck me as possibly inappropriate thoughts, such as "my car keys are in the overhead locker; that means if I'm forced to leave them I'll have to find a alternative way home and return to Gatwick just to pick up my car. Or, as I'm flying again from Gatwick next week, should I just leave my car there?". Perhaps I, too, should have had different priorities...or perhaps this is one ways the mind diverts someone from dwelling too much on the reality of the situation.
P.S. Apologies for the thread drift.
Having experienced an emergency landing as a passenger (the real thing, including the "brace" position) I think I may have some insight into the behaviour of the passenger who wanted to get his passport. As we were descending I had what later struck me as possibly inappropriate thoughts, such as "my car keys are in the overhead locker; that means if I'm forced to leave them I'll have to find a alternative way home and return to Gatwick just to pick up my car. Or, as I'm flying again from Gatwick next week, should I just leave my car there?". Perhaps I, too, should have had different priorities...or perhaps this is one ways the mind diverts someone from dwelling too much on the reality of the situation.
P.S. Apologies for the thread drift.
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Did anyone notice on the footage that a passenger recorded, the Cabin Crew had a meal cart in the isle, and it looked as if they were serving meals like nothing had happened, anyway looked a bit strange to continue the meal service in the middle of an emergency.
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(Retired 757/767 captain)
Can anyone tell me (Rainboe maybe?) how the pilots would know that they were not breathing O2 if their cylinder had disappeared? My memory of performing and watching countless Rapid Depressurisation scenarios in the simulator is that the initial actions were;-
Oxygen masks and regulators...... ON, 100% (and the 100% was set pre-flight)
Crew Communications.... Establish.
So long as the flow to the masks was not restricted in some way I'm not sure they would know that there was no oxygen flow. Perhaps the 744 has a crew bottle contents guage or a Status message will appear.
Any ideas folks?
Can anyone tell me (Rainboe maybe?) how the pilots would know that they were not breathing O2 if their cylinder had disappeared? My memory of performing and watching countless Rapid Depressurisation scenarios in the simulator is that the initial actions were;-
Oxygen masks and regulators...... ON, 100% (and the 100% was set pre-flight)
Crew Communications.... Establish.
So long as the flow to the masks was not restricted in some way I'm not sure they would know that there was no oxygen flow. Perhaps the 744 has a crew bottle contents guage or a Status message will appear.
Any ideas folks?
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Look at the second picture on post 359. Look at the top left corner of hole, where a major piece of skin is bent upward. You have the green coloured aircraft skin, but inside of that, you can see the slightly darker coloured green, of an O2 bottle still in situ. Now the missing bottle/bottles and relevant supply pipework, would be where the hole is, moving forward to the front of the aircraft. I imagine that passengers may have trouble with their O2 supply, with quite a large percentage of the system missing. I do not suppose Boeing, when designing the system, built in fail safes for completely missing bottles within the system, which also by its very failure, possibly caused the decompression which the system was there to protect against!
As to starting the supply to the mask of each individual passenger and if the design has not changed from -200 days, you would pull the mask towards you and a length of cord attached to both the mask and a plastic pin in the oxygen drop down assembly supply manifold, would be removed, so allowing supply to the mask.
As to starting the supply to the mask of each individual passenger and if the design has not changed from -200 days, you would pull the mask towards you and a length of cord attached to both the mask and a plastic pin in the oxygen drop down assembly supply manifold, would be removed, so allowing supply to the mask.
A few general comments.
A jet propelled oxygen tank takes a fair amount of travel distance in meters or yards to get up enough velocity to punch through aircraft skin. (reference the Mythbuster documentation on TV)
Exploding oxygen tanks leave smaller fragments behind to pepper the inside skin.
The support for the oxygen tanks is very likely to be compromised when the fuselage ruptures nearby.
Explosive decompressions create pressure gradients across nearby large area surfaces which in turn cause them to accelerate outward towards the hole.
To my knowledge no investigator is saying the oxygen containers ruptured first.
Anybody got any better schematics or pictures to corral this discussion
A jet propelled oxygen tank takes a fair amount of travel distance in meters or yards to get up enough velocity to punch through aircraft skin. (reference the Mythbuster documentation on TV)
Exploding oxygen tanks leave smaller fragments behind to pepper the inside skin.
The support for the oxygen tanks is very likely to be compromised when the fuselage ruptures nearby.
Explosive decompressions create pressure gradients across nearby large area surfaces which in turn cause them to accelerate outward towards the hole.
To my knowledge no investigator is saying the oxygen containers ruptured first.
Anybody got any better schematics or pictures to corral this discussion
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Did anyone notice on the footage that a passenger recorded, the Cabin Crew had a meal cart in the isle, and it looked as if they were serving meals like nothing had happened, anyway looked a bit strange to continue the meal service in the middle of an emergency.
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More tank hints...
Australia's Civil Aviation Authority (CASA) said Qantas has agreed to inspect oxygen bottles on its fleet of 30 747s.
CASA spokesman Peter Gibson said: "There are two cylinders located pretty much exactly where that hole appeared."
He added: "We do know there were two oxygen bottles in that area, we do know they're a main focus of the investigation, and we think it's prudent to put safety first, to get inspections done now rather than wait any longer."
Smug grins all round then from people who suggested tanks in the first place.
I still like meteors myself, there's a new Airport movie in that, surely
CASA spokesman Peter Gibson said: "There are two cylinders located pretty much exactly where that hole appeared."
He added: "We do know there were two oxygen bottles in that area, we do know they're a main focus of the investigation, and we think it's prudent to put safety first, to get inspections done now rather than wait any longer."
Smug grins all round then from people who suggested tanks in the first place.
I still like meteors myself, there's a new Airport movie in that, surely
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Despite the fact that the elastic on the mask was deteriorated, David still had oxygen from what I gather. When one bottle goes, dosn't all the O2, secondly, you would only need to check the aircraft and make sure each oxy mask door was open in the cabin. Wouldnt that be enough to explain if the oxy bottle had failed or not?
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as pilots, the donning of the oxygen mask is a vital part of our training...but there has been very little in the way of...OXYGEN NOT FLOWING...what do I do now?
certainly manipulating the toggle switches...but to have it fail and then get out the walk around bottle is alot to ask.
I do think the whole planeload was lucky that the plane was at FL290 and not higher.
While I know the everglades/valujet crash was due to the oxygen generators (and fuel...tires in cargo hold), few may remember that the lines to the oxygen regulator had been compromised even prior to flight.
I sure hope the brave QANTAS pilots had actually checked their oxygen masks before flight by placing them on their face and breathing...under pressure.
certainly manipulating the toggle switches...but to have it fail and then get out the walk around bottle is alot to ask.
I do think the whole planeload was lucky that the plane was at FL290 and not higher.
While I know the everglades/valujet crash was due to the oxygen generators (and fuel...tires in cargo hold), few may remember that the lines to the oxygen regulator had been compromised even prior to flight.
I sure hope the brave QANTAS pilots had actually checked their oxygen masks before flight by placing them on their face and breathing...under pressure.
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Attn. Peter McGrath re. post 405
Splendid graphics, Peter! Looks like a stringer to me. As to which one, we have plenty of choice. If it failed concurrently with everything else, would it not be in the South China Sea right now? This seems to suggest that it got wedged inside at this interesting angle before the failure of the skin.
If it failed concurrently with everything else, would it not be in the South China Sea right now? This seems to suggest that it got wedged inside at this interesting angle before the failure of the skin.
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"The reason for our retirement was electrical failure. The con-rod broke through the side of the block and destroyed the alternator. "
Ho hum. The reason why the oxygen bottle is missing is because the piece of airframe to which it was attached is somewhere at the bottom of the Pacific.
Ho hum. The reason why the oxygen bottle is missing is because the piece of airframe to which it was attached is somewhere at the bottom of the Pacific.
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Cabin Crew here.
As far as I am aware, the decompression happened during or immediately after the meal service, meaning 365 would have had their layups. I agree that the crew were most likely clearing in those lay ups.
Personally, I would have gone through with our big garbage bags, and just chucked it all in, EasyJet style. I think we could clear in a 744 in about 10 minutes that way.
Following the descent, it may have been considerable time before landing into MNL. I presume the a/c also flies at slower speed at 10,000. Another theory is they were serving juice or water. Keeping the crew busy during an emergency is very important as it helps us remain calm and therefore more able to calm and reassure the pax. Not sure I'd do it on a cart though.
Congrats to all the crew, my thoughts are with all my friends who fly for the Q!
As far as I am aware, the decompression happened during or immediately after the meal service, meaning 365 would have had their layups. I agree that the crew were most likely clearing in those lay ups.
Personally, I would have gone through with our big garbage bags, and just chucked it all in, EasyJet style. I think we could clear in a 744 in about 10 minutes that way.
Following the descent, it may have been considerable time before landing into MNL. I presume the a/c also flies at slower speed at 10,000. Another theory is they were serving juice or water. Keeping the crew busy during an emergency is very important as it helps us remain calm and therefore more able to calm and reassure the pax. Not sure I'd do it on a cart though.
Congrats to all the crew, my thoughts are with all my friends who fly for the Q!
Splendid graphics, Peter! Looks like a stringer to me. As to which one, we have plenty of choice. If it failed concurrently with everything else, would it not be in the South China Sea right now? This seems to suggest that it got wedged inside at this interesting angle before the failure of the skin.
I am still hoping that some of our graphics artists could transpose that fuzzy piece in the incident picture to overlay the clear interior reference photo that Machaca posted.
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All wet areas and bilges are painted white, notice alot of bare aluminium skin on the upper folded peice (inner surface), could that paint be missing due to oxygen blast onto the skin, how else does this paint go missing or removed ?? Zoom up and have a look.
Last edited by SUB; 27th Jul 2008 at 15:04.
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Dynamite not required
There's been a suggestion that some sort of fire or pyrolytic reaction is implicit in an 'explosion' — that chemical explosives are needed, and scorch-marks will ensue. This is not the case. An explosion is any rapid and uncontrolled evolution of gas. It doesn't matter what the gas is, or how you achieve it.
An explosive is a material which, when detonated, undergoes an extremely rapid chemical reaction involving the evolution of a colossal volume of gas very quickly. Detonation is the process of raising the chemical system above the energy level required for the reaction to take place.
An extremely large volume of gas being rapidly liberated from a fragmenting cylinder is an explosion.
As to the likelihood of fire being associated with an O2 leak, it's not compulsory: if there's no ignition source to hand, there will be no fire. There are materials that will spontaneously combust in pure O2, but we're not likely to see any of those in the hold of an aeroplane.
Finally, yes, a rocketing gas tank would need to accelerate for a few metres to knock a hole in a seam, but that folded-up bit of fuselage is interesting nevertheless. Were there any gas tanks in that hold other than the ones that were (theoretically) bolted to the sides? Any scuba enthusiasts on board?
An explosive is a material which, when detonated, undergoes an extremely rapid chemical reaction involving the evolution of a colossal volume of gas very quickly. Detonation is the process of raising the chemical system above the energy level required for the reaction to take place.
An extremely large volume of gas being rapidly liberated from a fragmenting cylinder is an explosion.
As to the likelihood of fire being associated with an O2 leak, it's not compulsory: if there's no ignition source to hand, there will be no fire. There are materials that will spontaneously combust in pure O2, but we're not likely to see any of those in the hold of an aeroplane.
Finally, yes, a rocketing gas tank would need to accelerate for a few metres to knock a hole in a seam, but that folded-up bit of fuselage is interesting nevertheless. Were there any gas tanks in that hold other than the ones that were (theoretically) bolted to the sides? Any scuba enthusiasts on board?
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Oxy cyilnders
I know it`s some years since i worked on the Qantas 747-400 but some points need answering from memory.
1st There are several bottles in the rack 6 or 8 from memory. there is a non return valve between each bottle so the loss of one especially at the end of rhe line would not drain all the others.
2nd The way the bottles are secured it is very uinlikely that the bottle exited the aircraft in one peice, I would suspect a bottle failed & the shrapnel caused the damage.
3rd The crew have their own supply of oxygen totally seperate from the pax supply.
tristar 500
1st There are several bottles in the rack 6 or 8 from memory. there is a non return valve between each bottle so the loss of one especially at the end of rhe line would not drain all the others.
2nd The way the bottles are secured it is very uinlikely that the bottle exited the aircraft in one peice, I would suspect a bottle failed & the shrapnel caused the damage.
3rd The crew have their own supply of oxygen totally seperate from the pax supply.
tristar 500