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  #1  
Old 06-05-2009, 08:31 PM
The Great Philosopher The Great Philosopher is offline
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What would a plane crash like the Air France one be like from inside the plane?

I realize no one seems to be sure exactly what happened to the Air France flight that crashed in the Atlantic between Rio and Paris. But I've read a few expert opinions that suspect that roughly what happened is this: the plane was flying through a thunderstorm and severe turbulence (the pilots were possibly having to fly it manually - after ice blocked up certain autopilot instruments - and without certain gauges). This required it to fly within an exact speed range - too fast and it would start to break up in the pressure of the storm, too slow and it would stall, and with a plane that size in conditions that difficult the stall would be an irreversible one. Some experts have been suggesting the plane stalled and then started to break up in mid-air.

My question is, what would any of these scenarios be like from inside the plane?

1) If a plane stalls: what happens, does the plane just start heading downwards? Are the pilots still vaguely controlling where it lands, like the plane Sullenberger landed in the Hudson?
2) If a plane 'breaks up in mid-air': what does this mean and what would it be like for passengers? I have an image of planes splitting into separate pieces and just falling from the sky (something like an aerial Titanic), but I suspect it means something more like, crucial pieces getting ripped off the plane and forcing an emergency landing. Either of these? I read a news story which contended that, if the cabin is breached and loses pressure, all passengers would fall unconscious immediately, and that this is probably what happened on the Air France flight.
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  #2  
Old 06-05-2009, 08:39 PM
cmyk cmyk is online now
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I have no idea, but I'd like to join you in the morbid curiosity of the scenario. I hope to god no one had to stay conscious very long to witness their demise, let alone plummet toward the ocean.
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  #3  
Old 06-05-2009, 08:57 PM
Huerta88 Huerta88 is offline
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30 seconds to unconsciousness is a number I've heard a few times. When Payne Stewart's plane depressurized at altitude we were assured that unconsciousness was "nearly instantaneous.". Though several of the Challenger astronauts were apparently alive (if knocked out) when they hit the water (they deduced this from their emergency oxygen having been used -- but of course there is no emergency oxygen available if your aircraft breaks up in mid-air). The Japan Airlines flight that crashed into a montain depressurized and people were alive till impact, but that happened during the climb, much lower than 35k feet.
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Old 06-05-2009, 09:02 PM
Johnny L.A. Johnny L.A. is online now
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What would a plane crash like the Air France one be like from inside the plane?

Unpleasant.




I've had a book on (General Aviation) crash investigations on my shelf for a while, and I just picked it up the other day. I've only read the introduction, deciding I'd save it for my flights to New Orleans. Of course, by the time I read it this thread will no longer be topical.

Anyway. A 'stall' means an 'aerodynamic stall'. A lot of people think it means the engines. Basically, when the air comes unstuck from the wings, the wings no longer generate sufficient lift for flight. Stall behaviour is different for different aircraft. Some stalls are mild, and some are nasty. For example, practicing stalls in a Cessna is fun. Stalling a rotor on a helicopter would be fatal. But generally, an airplane isn't going to 'fall out of the sky' after a stall. Get the air flowing over the wings (lower the nose) and they start flying again. Usually. In wind shear conditions it might be more difficult. For one thing, wind shear is a change in velocity. You could recover from a stall and get into another one when you fly into another mass of air moving in a different direction.

Another factor is that an airplane can stall at any speed. Exceed the critical angle of attack (by hitting wind sheer or even overcontrolling) and you can stall. So let's say you get into wind shear and stall. You point the nose down to recover. Then you hit different-direction wind. Suddenly you're exceeding VNE (never-exceed speed). I'm not going to run through every possible scenario, so let me just do this one. Your airspeed is much faster than the aircraft is designed for. Let's say this causes flutter (fluttering of control surfaces). The control surface can't take the stress and breaks off. Maybe it's still attached by a control cable, and starts banging against the rest of the structure. Or maybe it puts the aircraft into a seriously wrong position. A tailplane that's flapping in the breeze could tear off the aft end of the fuselage. Now you've got this huge twisting force on the wings, and they rip off. So the passengers would be in a tumbling tube with positive, negative, and other G-forces acting on them like one of those ring things you can strap into at a carnival.

As for losing consciousness after losing cabin pressure, I've been through an altitude chamber. One of the exercises was rapid decompression. We were in an antechamber with a simulated altitude of 8,000 feet. The main chamber was at like 30,000 feet. As the instructor lulled us into complacency with his lesson, a valve was opened between the chambers. Instantly the antechamber filled with fog as it lost its pressure. We donned out masks and hit the 100% switch. Nobody passed out. That was the most fun I had in the chamber. I wished we could do it a few more times. But we had our masks hanging off of our helmets. A passenger in an airplane that was breaking apart and tumbling would have little chance to grab the oxygen mask and would likely lose consciousness in just a couple of minutes.
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Old 06-05-2009, 09:16 PM
mangeorge mangeorge is offline
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Oh, that one.

I clicked over here thinking the Title said "Air Force One". I hope the nsa doesn't make the same mistake.
Anyway, my curiosity is piqued, so I'll read this.
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  #6  
Old 06-05-2009, 09:17 PM
Xema Xema is offline
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Quote:
Originally Posted by The Great Philosopher View Post
If a plane stalls: what happens, does the plane just start heading downwards? Are the pilots still vaguely controlling where it lands, like the plane Sullenberger landed in the Hudson.
Some misconceptions here.

An aerodynamic stall isn't necessarily a catastrophic event - indeed it and the recovery can be reasonably easy (though this is much more likely to be true when the pilot is ready for it). There's certainly no reason why it could not be accomplished in substantially less than 35,000'.

Oversimplified, a stall occurs when some aerodynamic surface (most often a wing) exceeds its critical angle of attack. The result is a rapid loss of a high percentage of the lift being produced. If both wings stall together the nose drops, angle of attack becomes substantially lower, the airspeed increases, and the plane flies off happily having lost some altitude. A stall that involves just one wing is more of a problem, as it tends to lead to a spin entry (typically a bit harder to recover from, and likely to consume more altitude but still by no means impossible).

The plane that landed in the Hudson River was under full control through the entire event (well, until it was in the water).

Last edited by Xema; 06-05-2009 at 09:19 PM..
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  #7  
Old 06-05-2009, 09:24 PM
Johnny L.A. Johnny L.A. is online now
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Helpful links:

Aerodynamic stall

Flutter
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  #8  
Old 06-05-2009, 09:30 PM
Rand Rover Rand Rover is offline
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I've experienced lots of full stalls in a Cessna 172 (all purposeful, thank god). The airplane goes into a dramatic nose-down attitude very quickly. Different planes are different as Johnny pointed out, but if an airliner acts anything like a 172, then I'd imagine that the initial nose-down attitude would essentially shake the hell out of everything. My guess is that a very substantial number of people would be knocked unconscious almost instantly, not experiencing any of the rest of the flight.
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  #9  
Old 06-05-2009, 10:21 PM
Whack-a-Mole Whack-a-Mole is offline
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One can only hope that the passengers and crew fell into unconsciousness in short order.

A human in free fall drops roughly 10,000 feet/minute. Granted different things drop at different rates in an atmosphere but lets go with that as a very rough guess.

Assuming that number and assuming* the plane plummeted straight into the ocean that is a 4 minute fall. The horror of that if you were conscious the whole way boggles the mind.


*- Note planes may not just "fall" straight down. IIRC TWA-800 had the front 1/4 of the plane fall off. The rest, including the wings, was in one piece. The reconstruction I saw showed the plane do a roller coaster maneuver...nose drops off plane loses weight up front and pitches up...plane stalls and pitches down...picks up speed, gains lift again and pitches up. Since the plane was at a relatively low altitude it is believed likely some passengers were conscious all the way.

Last edited by Whack-a-Mole; 06-05-2009 at 10:23 PM..
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  #10  
Old 06-06-2009, 09:29 AM
The Great Philosopher The Great Philosopher is offline
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I'm not particularly interested in the aerodynamics of what a stall is or how it occurs - I'd already read those wikipedia links about it - as I am in what it would be like for the passengers.

As for (2), does anyone know what 'breaking up' even means for a plane in mid-air? And what would it be like for the passengers?
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  #11  
Old 06-06-2009, 09:30 AM
The Great Philosopher The Great Philosopher is offline
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Quote:
Originally Posted by Whack-a-Mole View Post
One can only hope that the passengers and crew fell into unconsciousness in short order.

A human in free fall drops roughly 10,000 feet/minute. Granted different things drop at different rates in an atmosphere but lets go with that as a very rough guess.

Assuming that number and assuming* the plane plummeted straight into the ocean that is a 4 minute fall. The horror of that if you were conscious the whole way boggles the mind.


*- Note planes may not just "fall" straight down. IIRC TWA-800 had the front 1/4 of the plane fall off. The rest, including the wings, was in one piece. The reconstruction I saw showed the plane do a roller coaster maneuver...nose drops off plane loses weight up front and pitches up...plane stalls and pitches down...picks up speed, gains lift again and pitches up. Since the plane was at a relatively low altitude it is believed likely some passengers were conscious all the way.
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  #12  
Old 06-06-2009, 09:50 AM
Johnny L.A. Johnny L.A. is online now
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Originally Posted by The Great Philosopher View Post
As for (2), does anyone know what 'breaking up' even means for a plane in mid-air? And what would it be like for the passengers?
See post #4. I described one break-up scenario there.

To reiterate: Something breaks off. This results in over-stressing other things that break off. Passengers are thrown around violently. They are rendered unconscious or dead by being thrown about, or by hypoxia from not having access to supplemental oxygen.
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  #13  
Old 06-06-2009, 10:05 AM
Oregon sunshine Oregon sunshine is offline
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Tangentially related:

The Free Fall Research Page. There are some survivors' first-hand accounts of falling out of the sky without a parachute... others were unconscious throughout some or most of their free-falls.

Also, I'm reminded of the scene in Fight Club where the Narrator is imagining his own demise by airliner breaking up in the air. It was intended to be darkly humorous I know, but was done "realistically" enough it freaked the **** out of me.

Werner Herzog also made a film, Wings of Hope, about Juliane Koepcke, who survived after the plane she was in broke up in the air. (the only survivor, she fell two miles still strapped in her seat). Haven't seen it, but it might provide some insight into what it's like to be in such a crash.

Last edited by Oregon sunshine; 06-06-2009 at 10:09 AM.. Reason: to add the Herzog film
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  #14  
Old 06-06-2009, 10:13 AM
Beware of Doug Beware of Doug is offline
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Originally Posted by Johnny L.A. View Post
Unpleasant.
As naval aviators say with their characteristic sangfroid, "Ruin your whole day."
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Old 06-06-2009, 10:19 AM
LSLGuy LSLGuy is online now
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Former big jet pilot here ...

Assuming the early overly-sensational news reports about flying through a thunderstorm followed by electrical problems are accurate, it would have been a pretty exciting experience for all aboard. Perhaps a peak experience for all.

Truly severe turbulence, enough to damage the aircraft, would be insane in the cabin.

Overhead bins would be opening, spilling stuff everywhere. Which would then be bouncing from floor to ceiling, over and over, along with anyone not belted in. There would be a lot of creaking and groaning noises as the cabin interior flexed along with the airframe. There are lots of joints in the interior to let it shift as the airframe flexes in normal flight, and they'd all be getting a max-case workout.

Meanwhile there is nearly continuous lightning outside. And the airplane is rolling side to side 20+ degrees every few seconds. Plus some drunken sideways lurches that are surprisingly unnerving in an airplane.

And 90% of the people are screaming. Maybe not at first, but the above conditions could easily last 5 minutes. Once the least stable person starts screaming, the mob effect quickly takes over.

Had they been lucky, about now they come out the other side of the storm line. Well over half the people have shit themselves, a couple dozen people have concussions or broken limbs from being hit with flying suitcases & stuff. A handful of people with weak hearts have had heart attacks & died. The airplane is fine, and the pilots divert to the nearest airport able to handle the injured. Which out over the Atlantic may be 2+ hours away.


But they weren't lucky.

For whatever reason, the aircraft lost most electrical power and the pilots were flying off standby instruments.

Now it's pitch dark in the cabin (except for the lightning outside). In a cruel irony, the "floor lighting will lead you to an exit" lights will be on. Not that those exits do any good 7 miles up.

Now the pitch and roll gyrations get more extreme. Flying a half-powered airplane off the standby instruments is damn hard.

Maybe they get a little too nose low and within a few seconds are over-speeding. Something breaks off. More likely, they got a little slow and that combined with an updraft caused an aerodynamic stall. if they hit a strong enough updraft, they don't even need to have gotten slow.

Unlike the stalls described by light plane pilots above, stalling a big jet is quite a ride on a good day in smooth air. At night in extreme turbulence, it's the coup de grace.

You'd expect a severe and nearly instant roll one way or the other, easily past 45 degrees, and maybe to 90 degrees or more. (i.e. one wing pointing straight down, the other straight up). Perhaps an engine breaks off as they are designed to do.

Then the aircraft either snaps over the other way, or tries to keep rolling onto its back. Full opposite control inputs may not be enough.

Now the nose starts to fall and the speed pick up. A couple more gyrations and they get it under control. Or they don't, and from on its back they end up diving more or less vertically.

After 10-15 seconds of that, something catastrophic breaks off. A big piece of wing or tail. Now the unbalanced aircraft cartwheels more or less sideways. Within the next few seconds the fuselage breaks into several large pieces. At this point pressurization fails and the people are suddenly exposed to -30 to -50 degree temperatures and low pressure. As well as all the flailing wires and broken airplane chunks whipping around in the 300-600 mph wind. The lightning hasn't stopped either.

Assuming you've got a good heart, are wearing your seatbelt and aren't right at the edge of a chunk, you're still 100% alive, conscious, & uninjured. Scared and doomed, but uninjured.

Due to the extreme adrenaline rush, folks will be using up blood oxygen at a furious pace. Many will lose consciousness due to lack of air pressure at altitude. But far from all.

And because you're falling into thicker air at a pretty good clip, I'd wager all but the elderly will revive to at least a groggy state prior to impact. It'll take 2-ish minutes for the fuselage chunks to fall to the sea. Many will be fully conscious and aware for the entire ride.

The final impact will kill 99% of the people, and critically injure the last 2 lucky (?) souls. Who'll drown as their fuselage chunk sinks with them still strapped in.

All in all, probably a peak experience.
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Old 06-06-2009, 10:20 AM
Johnny L.A. Johnny L.A. is online now
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Here's an example of an in-flight break-up of a GA airplane from Air Crash Investigation Of General Aviation Aircraft (removed illustration references):
Quote:
The location of the pieces of wreckage and their condition tell much of the story: The aircraft was last reported passing the VOR, and it had turned onto the new heading called for by the flight plan. For some reason, the airspeed increased to such a high speed that a tail flutter developed. It was the violence of this flutter that caused the tail to separate from the aircraft and fly up over the cabin, resulting in the tumbling of the aircraft. The wings were broken off due to the air load pressure on top of them, and the lighter parts continued on as the cabin, engine, and propeller fell almost vertically. The tail, having finally broken the steel cables, was found just beyond.
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  #17  
Old 06-06-2009, 10:45 AM
The Great Philosopher The Great Philosopher is offline
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Quote:
Originally Posted by LSLGuy View Post
Former big jet pilot here ...

Assuming the early overly-sensational news reports about flying through a thunderstorm followed by electrical problems are accurate, it would have been a pretty exciting experience for all aboard. Perhaps a peak experience for all.

Truly severe turbulence, enough to damage the aircraft, would be insane in the cabin.

Overhead bins would be opening, spilling stuff everywhere. Which would then be bouncing from floor to ceiling, over and over, along with anyone not belted in. There would be a lot of creaking and groaning noises as the cabin interior flexed along with the airframe. There are lots of joints in the interior to let it shift as the airframe flexes in normal flight, and they'd all be getting a max-case workout.

Meanwhile there is nearly continuous lightning outside. And the airplane is rolling side to side 20+ degrees every few seconds. Plus some drunken sideways lurches that are surprisingly unnerving in an airplane.

And 90% of the people are screaming. Maybe not at first, but the above conditions could easily last 5 minutes. Once the least stable person starts screaming, the mob effect quickly takes over.

Had they been lucky, about now they come out the other side of the storm line. Well over half the people have shit themselves, a couple dozen people have concussions or broken limbs from being hit with flying suitcases & stuff. A handful of people with weak hearts have had heart attacks & died. The airplane is fine, and the pilots divert to the nearest airport able to handle the injured. Which out over the Atlantic may be 2+ hours away.


But they weren't lucky.

For whatever reason, the aircraft lost most electrical power and the pilots were flying off standby instruments.

Now it's pitch dark in the cabin (except for the lightning outside). In a cruel irony, the "floor lighting will lead you to an exit" lights will be on. Not that those exits do any good 7 miles up.

Now the pitch and roll gyrations get more extreme. Flying a half-powered airplane off the standby instruments is damn hard.

Maybe they get a little too nose low and within a few seconds are over-speeding. Something breaks off. More likely, they got a little slow and that combined with an updraft caused an aerodynamic stall. if they hit a strong enough updraft, they don't even need to have gotten slow.

Unlike the stalls described by light plane pilots above, stalling a big jet is quite a ride on a good day in smooth air. At night in extreme turbulence, it's the coup de grace.

You'd expect a severe and nearly instant roll one way or the other, easily past 45 degrees, and maybe to 90 degrees or more. (i.e. one wing pointing straight down, the other straight up). Perhaps an engine breaks off as they are designed to do.

Then the aircraft either snaps over the other way, or tries to keep rolling onto its back. Full opposite control inputs may not be enough.

Now the nose starts to fall and the speed pick up. A couple more gyrations and they get it under control. Or they don't, and from on its back they end up diving more or less vertically.

After 10-15 seconds of that, something catastrophic breaks off. A big piece of wing or tail. Now the unbalanced aircraft cartwheels more or less sideways. Within the next few seconds the fuselage breaks into several large pieces. At this point pressurization fails and the people are suddenly exposed to -30 to -50 degree temperatures and low pressure. As well as all the flailing wires and broken airplane chunks whipping around in the 300-600 mph wind. The lightning hasn't stopped either.

Assuming you've got a good heart, are wearing your seatbelt and aren't right at the edge of a chunk, you're still 100% alive, conscious, & uninjured. Scared and doomed, but uninjured.

Due to the extreme adrenaline rush, folks will be using up blood oxygen at a furious pace. Many will lose consciousness due to lack of air pressure at altitude. But far from all.

And because you're falling into thicker air at a pretty good clip, I'd wager all but the elderly will revive to at least a groggy state prior to impact. It'll take 2-ish minutes for the fuselage chunks to fall to the sea. Many will be fully conscious and aware for the entire ride.

The final impact will kill 99% of the people, and critically injure the last 2 lucky (?) souls. Who'll drown as their fuselage chunk sinks with them still strapped in.

All in all, probably a peak experience.
That scenario (ie. what I called the 'aerial Titanic' scenario: the fuselage breaks into several large pieces, so passengers fall straight downwards, looking out into the sky, then sink strapped to the large pieces of metal) is pretty much the nightmare scenario that I was wondering about. I hope to God that's not what happened to the Air France flight.

Quote:
Originally Posted by Johnny L.A.
To reiterate: Something breaks off. This results in over-stressing other things that break off. Passengers are thrown around violently. They are rendered unconscious or dead by being thrown about, or by hypoxia from not having access to supplemental oxygen.
This was more what I figured 'breaking apart in mid-air' probably meant; crucial external pieces break off rendering the plane un-flyable, passengers quickly lose consciousness due to the turbulence or the loss of cabin pressure, and the plane head downwards fairly quickly. Not as bad as the scenario above but still not exactly pleasant. As far as the Air France flight goes I find it (morbidly) comforting that because the plane didn't send any mayday signals other than automatic ones (including the automatic message that the cabin had lost pressure), that probably means the pilots fell unconscious very quickly, which hopefully means no one on board was conscious for whatever happened, especially if it was one of the scenarios painted here...
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  #18  
Old 06-06-2009, 10:49 AM
Johnny L.A. Johnny L.A. is online now
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Originally Posted by The Great Philosopher View Post
Not as bad as the scenario above but still not exactly pleasant.
Oh, it's just as bad. I was just trying to fit it into a nutshell. LSLGuy's excellent post gave us the graphic details. (With the bonus about stall behaviour of big jets.)

Last edited by Johnny L.A.; 06-06-2009 at 10:49 AM..
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  #19  
Old 06-06-2009, 11:13 AM
LSLGuy LSLGuy is online now
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Quote:
Originally Posted by The Great Philosopher View Post
That scenario (ie. what I called the 'aerial Titanic' scenario: the fuselage breaks into several large pieces, so passengers fall straight downwards, looking out into the sky, then sink strapped to the large pieces of metal) is pretty much the nightmare scenario that I was wondering about. I hope to God that's not what happened to the Air France flight.



This was more what I figured 'breaking apart in mid-air' probably meant; crucial external pieces break off rendering the plane un-flyable, passengers quickly lose consciousness due to the turbulence or the loss of cabin pressure, and the plane head downwards fairly quickly. Not as bad as the scenario above but still not exactly pleasant. As far as the Air France flight goes I find it (morbidly) comforting that because the plane didn't send any mayday signals other than automatic ones (including the automatic message that the cabin had lost pressure), that probably means the pilots fell unconscious very quickly, which hopefully means no one on board was conscious for whatever happened, especially if it was one of the scenarios painted here...
People do not lose consciousness from turbulence, period. People lose consciouslness from depressurization slowly, over a span of 30-300 seconds depending on altitude & stress. All the while descending to thicker air.

The relationship between the curve of altitude lost & air pressure gained per unit time while falling versus the curve of time to unconscious at any given pressure pretty well guarantee that everyone other than the frail remain awake and alert throughout.


[pet rant mode=on]
I really do not understand the common mentality that keeps trying to assert that humans will become unconscious before they die unpleasantly. People, by and large, don't.

Back after 9/11 there was a lot of discussion about how people jumping out of the buildings would somehow become unconscious. Bogus.

When someone is mauled by a zoo animal folks want to claim that the idiot who wanted to swim with the polar bears or cavort with the lions lost unconsciousness at the first hostile snarl. Not so.

Folks, the world does not work that way.
[pet rant mode=off]
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Old 06-06-2009, 11:23 AM
Johnny L.A. Johnny L.A. is online now
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Quote:
Originally Posted by LSLGuy View Post
People do not lose consciousness from turbulence, period.
I could envision a case where turbulence can cause unconsciousness: shaken-baby syndrome. I assume it could happen in adults as well. This is not to say that people losing consciousness by violent movement of their heads happens with any frequency, or that it has ever happened; but it seems plausible to me. That is, I'm not disagreeing with you; just saying that it might happen rarely.
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Old 06-06-2009, 12:33 PM
DooWahDiddy DooWahDiddy is offline
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I really do not understand the common mentality that keeps trying to assert that humans will become unconscious before they die unpleasantly.
Wishful thinking.
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  #22  
Old 06-06-2009, 01:02 PM
Whack-a-Mole Whack-a-Mole is offline
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Originally Posted by LSLGuy View Post
I really do not understand the common mentality that keeps trying to assert that humans will become unconscious before they die unpleasantly. People, by and large, don't.
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Originally Posted by DooWahDiddy View Post
Wishful thinking.
Talking to my GF yesterday about the AF flight she opined that the oxygen masks should deliver Nitrous Oxide (laughing gas) in that situation.

Crazy but I'd sure wish it did.
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Old 06-06-2009, 03:31 PM
Doug Bowe Doug Bowe is offline
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Quote:
Originally Posted by Whack-a-Mole View Post
Talking to my GF yesterday about the AF flight she opined that the oxygen masks should deliver Nitrous Oxide (laughing gas) in that situation.

Crazy but I'd sure wish it did.

Done nitrous at the Dentist office. It takes a short while before fading in. I'm afraid you'd be on the ground (or in the ocean) before it would start to work.


edit: fixed spelling

Last edited by Doug Bowe; 06-06-2009 at 03:31 PM..
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  #24  
Old 06-06-2009, 03:44 PM
The Great Philosopher The Great Philosopher is offline
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Quote:
Originally Posted by LSLGuy View Post
People do not lose consciousness from turbulence, period.
You do if you get knocked unconscious. Not exactly hard to imagine in violent turbulence.

Quote:
People lose consciouslness from depressurization slowly, over a span of 30-300 seconds depending on altitude & stress. All the while descending to thicker air.
Any cite for this? If the fuselage splits apart you'd effectively instantly start breathing external air at 35,000 feet, and at that level I've read that without oxygen masks every passenger would be unconscious within about a minute.

Quote:
The relationship between the curve of altitude lost & air pressure gained per unit time while falling versus the curve of time to unconscious at any given pressure pretty well guarantee that everyone other than the frail remain awake and alert throughout.
Any cite?

Quote:
[pet rant mode=on]
I really do not understand the common mentality that keeps trying to assert that humans will become unconscious before they die unpleasantly. People, by and large, don't.

Back after 9/11 there was a lot of discussion about how people jumping out of the buildings would somehow become unconscious. Bogus.

When someone is mauled by a zoo animal folks want to claim that the idiot who wanted to swim with the polar bears or cavort with the lions lost unconsciousness at the first hostile snarl. Not so.

Folks, the world does not work that way.
[pet rant mode=off]
I think it's pretty obvious - maybe not to you, given that you sound like you take pleasure from 'idiots' being conscious to experience their horrific pain - that people like to think others who suffered terrifying or agonizing deaths were not conscious to experience it. I've never heard anyone claim that 9/11 victims or victims of animal attacks fell unconscious, clearly they didn't. But those situations are irrelevant; they're very different from the possibility of losing consciousness in an aircraft that's lost cabin pressure.

Like I said, I do hope no one would have been conscious for the entire experience on the Air France flight, but I'm sure they were conscious for at least a fair part of it, and if there's good evidence they would have been conscious for the whole thing I won't be able to deny it. But you haven't cited any good evidence for it other than a rant.
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  #25  
Old 06-06-2009, 03:54 PM
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http://en.wikipedia.org/wiki/Time_of..._Consciousness

I think that LSLGuy is trying to say is that as you're falling, you're gaining more and more useful conscious time. Assuming you didn't get bonked on your head and were strapped into your seat - and were falling fast enough - it's probably reasonable to assume that you would remain conscious the whole time.

I think a lot of people want to just assume unconsciousness because it's less horrible to imagine. But the reality of it is probably even more horrible.
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  #26  
Old 06-06-2009, 06:16 PM
Sunspace Sunspace is online now
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There was a movie that showed a plane crash, and one of the survivors becomes 'detached' from the world, walks away from the crash site and his old life, and does all kinds of crazy stuff... wish I could remember what it was called. The depiction of the plane in trouble with the cabin rotating and stuff--and people-- being thrown about was quite frightening. As soon as I heard about the crash, I was wondering whether it was like that. But LSLGuy's depiction is scarier.
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  #27  
Old 06-06-2009, 07:01 PM
Broomstick Broomstick is offline
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You do if you get knocked unconscious. Not exactly hard to imagine in violent turbulence.
Yes, but (nitpick mode) it's the knock on the head that renders you unconscious, not the turbulence.

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Any cite for this? If the fuselage splits apart you'd effectively instantly start breathing external air at 35,000 feet, and at that level I've read that without oxygen masks every passenger would be unconscious within about a minute.
The thing is, gravity takes over. You don't stay at 35,000 feet. within a minute you'll be at 25,000 feet, which is approximately the height of Mt. Everest - a place where people can breathe and remain conscious without supplemental oxygen although their thinking is impaired. In another minute you'll be at 15,000 feet, which would be uncomfortable if you stayed there without acclimatization but you aren't staying there, you're still falling, and because there's more oxygen your brain may be functioning better by that point. Another minute and you're at 5,000 feet, the altitude of Denver, Colorado which is quite compatible with life and awareness. 30 second later, more or less, you're at sea level or ground level, at which point getting enough oxygen is no longer your primary problem. Even if you black out briefly at 35,000 feet, increasing oxygen during your fall will most likely allow you to wake up again.

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Any cite?
LSLGuy is professional pilot flying big jets, studying the effects of depressurization is a requirement for obtaining the necessary certifications to do that.

If it helps though here is a link to a discussion of the matter by another professional pilot.

Wikipedia isn't the most solid source, but here is a wiki that provides a reasonable overview of decompression[/url]. Notably, there is a list of decompression incidents and accidents, mostly airplane connected, that will allow you to read about past occurrences should you be so inclined.

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I think it's pretty obvious - maybe not to you, given that you sound like you take pleasure from 'idiots' being conscious to experience their horrific pain - that people like to think others who suffered terrifying or agonizing deaths were not conscious to experience it.
I don't think LSLGuy gets any joy from contemplating a conscious free-fall minus parachute from 35,000 feet, particularly as it is a (admittedly small) occupational risk for him on some level. I think what it is, is that he has a better grasp of the facts than the average person and finds it frustrating when people would prefer to hold onto their ignorance or misinformation, even if some of the reasons for that are understandable.

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I've never heard anyone claim that 9/11 victims or victims of animal attacks fell unconscious, clearly they didn't.
I have. But let's not get into an argument about that - perhaps the people you have to associate with are, on average, more intelligent and educated than the yahoos I share my neighborhood with.

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But those situations are irrelevant; they're very different from the possibility of losing consciousness in an aircraft that's lost cabin pressure.

Like I said, I do hope no one would have been conscious for the entire experience on the Air France flight, but I'm sure they were conscious for at least a fair part of it, and if there's good evidence they would have been conscious for the whole thing I won't be able to deny it. But you haven't cited any good evidence for it other than a rant.
Again, LSLGuy was required to study the effects of depressurization as part of obtaining his license to fly the big airliners. He did not state his credentials, but given his occupation and training his words actually do carry some authority in this matter.
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Old 06-06-2009, 07:03 PM
Sunspace Sunspace is online now
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The movie was Fearless.

Last edited by Sunspace; 06-06-2009 at 07:04 PM..
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  #29  
Old 06-06-2009, 07:14 PM
Broomstick Broomstick is offline
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That scenario (ie. what I called the 'aerial Titanic' scenario: the fuselage breaks into several large pieces, so passengers fall straight downwards, looking out into the sky, then sink strapped to the large pieces of metal) is pretty much the nightmare scenario that I was wondering about. I hope to God that's not what happened to the Air France flight.
I hope so, too, but at this point it's still a possibility.

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This was more what I figured 'breaking apart in mid-air' probably meant; crucial external pieces break off rendering the plane un-flyable, passengers quickly lose consciousness due to the turbulence or the loss of cabin pressure, and the plane head downwards fairly quickly. Not as bad as the scenario above but still not exactly pleasant.
I'm not so sure about that - I don't think I'd find being contained in an aluminum tube while plunging to a certain death miles below would be any more comforting than plunging through open air. Of course, that's a personal opinion and clearly there is room for different people to feel differently about that one.

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As far as the Air France flight goes I find it (morbidly) comforting that because the plane didn't send any mayday signals other than automatic ones (including the automatic message that the cabin had lost pressure), that probably means the pilots fell unconscious very quickly, which hopefully means no one on board was conscious for whatever happened, especially if it was one of the scenarios painted here...
As comforting as that scenario may be, I think it more likely that the pilots were simply too busy trying to regain control of the airplane to send a mayday, as flying the airplane takes priority over talking on the radio. If the airplane did break up - either partially or entirely - due to turbulence there is no doubt in my mind that the ride prior to that event would FAR exceed any other turbulence you have ever experienced. I myself have experience turbulence on a passenger jet sufficient for overhead bins to open and luggage to go flying, unrestrained people to be tossed around, etc., yet I had no fear that that airplane was going to come apart. Likewise, I have been in a small airplane with stuff flying around the cabin and turbulence sufficient to leave bruises across both my shoulders and hips from the restraint harness, yet I had complete confidence the airplane could take the beating. Anything sufficient to shake apart an Airbus would be orders of magnitude worse than either of those two experiences, neither of which was any fun. My mind does tend to recoil from contemplating what an Airbus breakup would be like from the inside of the airplane, but when forced to look at the situation I think LSLGuy has the right of it.
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  #30  
Old 06-06-2009, 07:37 PM
Magiver Magiver is offline
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The stall scenario in this situation comes about from a procedure designed to smooth out turbulence. By slowing the plane down the pilot increases angle of attack to maintain altitude. I donít know the aerodynamics behind it but from personal experience it makes a huge difference. It appears that they lost the glass cockpit display, which is a series of flat panel screens that project information in place of a bunch of mechanical gauges. If in the process of losing this system they lost the sending units to the mechanical gauges then the pilot has slowed the plane down without a way to know where the stall speed is. Here is where things go wrong quickly. The pilot will be correcting for the left and right pitch using the ailerons. If the plane begins to stall it will naturally pitch down and also left or right. If the pilot attempts to correct using ailerons and up-elevator it will actually accelerate the stall. This will put the plane in a downward spiral. Instead of the air flowing over the wings it is now flowing perpendicular to the wing making it almost impossible to recover in clean air. We're talking 10 to 20,000 feet to recover in ideal conditions.

Unless the cabin depressurized early in this scenario it would have been a frightening event for all concerned.
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  #31  
Old 06-06-2009, 09:24 PM
Driver8 Driver8 is offline
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Originally Posted by Broomstick View Post
I myself have experience turbulence on a passenger jet sufficient for overhead bins to open and luggage to go flying, unrestrained people to be tossed around, etc., yet I had no fear that that airplane was going to come apart.
I did find this comment quite comforting actually. As a very nervous passenger even far milder turbulence puts me on edge, and every noise the plane makes me feel very unsafe. If I ever encountered turbulence that actually threw items around I would probably think I was going to die - I'll try to keep your comment in mind in such an occasion

I already knew, and it is obvious when thinking about it, that the plane can take stresses far greater than what makes me nervous. But it is difficult as a layperson strapped into the metal tube to suppress my evolutionary survival instinct!
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Old 06-06-2009, 10:05 PM
RickJay RickJay is online now
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Originally Posted by The Great Philosopher View Post
Any cite for this? If the fuselage splits apart you'd effectively instantly start breathing external air at 35,000 feet, and at that level I've read that without oxygen masks every passenger would be unconscious within about a minute.
I can hold my breath for a minute. If I can go without oxygen for sixty seconds and not even get faint, why would LESS oxygen knock someone out in sixty seconds?
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  #33  
Old 06-07-2009, 01:49 AM
Magiver Magiver is offline
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I can hold my breath for a minute. If I can go without oxygen for sixty seconds and not even get faint, why would LESS oxygen knock someone out in sixty seconds?
Unless you had the advantage of holding your breath before the event you will be breathing air at 35000 feet. You'll be doing this with your heart racing due to the adrenaline flooding your body in preparation of the fight or flight response. Unfortunately, there's no place to run.
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  #34  
Old 06-07-2009, 05:35 AM
Broomstick Broomstick is offline
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I can hold my breath for a minute. If I can go without oxygen for sixty seconds and not even get faint, why would LESS oxygen knock someone out in sixty seconds?
Because if the airplane depressurizes suddenly at 35,000 feet you won't be able to hold your breathe (in fact, attempting to do so can result in lung damage). The pressure differential will take most of the air out of your lungs, and since the partial pressure of oxygen in the surrounding air is less than what is in your body oxygen will move from your blood stream to the surrounding air until those partial pressures equalize. In addition your adrenaline-soaked body will be using oxygen faster than usual. You see, when you hold your breath you aren't really going without oxygen, you're using what's stored in your lungs. If you didn't have that store, if, in fact, oxygen is being drawn out of your body, you don't have as much time before you black out.
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Old 06-07-2009, 05:44 AM
Broomstick Broomstick is offline
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Originally Posted by Driver8 View Post
I did find this comment quite comforting actually.
Glad I could help.

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As a very nervous passenger even far milder turbulence puts me on edge, and every noise the plane makes me feel very unsafe.
I remember a time when I sat next to a nervous passenger who almost jumped out of his skin when the landing gear lowered. I reassured him that that was a GOOD noise, that meant the landing gear mechanism was working, and it was essential to hear that prior to a good landing. Part of the anxiety is that you don't know what all those sounds mean, if you did, you'd find them less nerve-wracking or even reassuring.

Quote:
If I ever encountered turbulence that actually threw items around I would probably think I was going to die - I'll try to keep your comment in mind in such an occasion
Try to - it IS scary and people DO get frightened. As I said, it's not fun. Two handy rules:

1) If the airline attendants aren't nervous, you shouldn't be nervous. If they're scared, you should be, too. They know what is and isn't normal.

2) Keep your seat belt on as much as possible. Of course, if you need to get up to pee you have to take it off, but your seat is the safest place to be, and the belt will keep you in it in the event of unexpected bumps. The people injured in turbulence almost always weren't in their seat, or weren't buckled in.

Quote:
I already knew, and it is obvious when thinking about it, that the plane can take stresses far greater than what makes me nervous. But it is difficult as a layperson strapped into the metal tube to suppress my evolutionary survival instinct!
I'm a pilot and my heart starts going faster when the air gets rough - the physical sensations alone can be disturbing, so don't be too hard on yourself. You're in a unfamiliar place with unfamiliar sensory input and no control over the situation, being a little nervous is completely understandable. Just remind yourself that aviation is, statistically speaking, an extremely safe form of travel, accidents are rare, airplanes are tough, and the pilots want to live, too.
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  #36  
Old 06-07-2009, 09:12 AM
LSLGuy LSLGuy is online now
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Wow - where to begin ???

Broomstick - Thank you.

The Great Philosopher / OP: I regret that you have so thoroughly misunderstood my points.

I live in a fact-based world. I might prefer that milk and honey flowed freely in the streets and that all kids grew up in a safe environment with caring parents and material plenty. Sadly, I know the world doesn't work that way. Even though I'm not an expert in those areas, I know and accept that the world doesn't work that way, at least not today.

I believe that for me to crimp my eyes shut and choose to believe that all kids do have a great life is to do them a disservice. It removes me from the pool of people who can care, who can do something about it. It transforms me into a let them eat cake kind of person, at least passively, if not actively.


Almost nobody sensible wants to die. Nobody sensible wants to die unpleasantly. Nobody sensible wants others to die unpleasantly.

We do the dead a disservice, a disrespect, by blythely assuming they didn't suffer, or "never knew what hit them". In doing so we are choosing to close our eyes to their reality. Why do we do that? I submit that's because it's too unpleasant in our reality. Are we so weak we can't withstand merely thinking about what others are forced to actually experience? That is cowardice.

You asked us what it was like for those poeple. I have unflinchingly told you what, in my professional opinion, I believe it was like. And I believe it was not pleasant.

I am not an accident investigator, although I have in my professional capacity read many dozens of accident reports over the years. I have watched helplessly as men died in aircraft. Not on youtube; for real. There is a difference.

I am not an aero engineer, although I have in my professional capacity read many books on the practical application thereof. I have been trained, practised, and been exhaustively evalauated on both my book knowledge and my practical use of that knowledge.

Among the ranks of the tens of thousands of pilots who fly or flew big jets, I'm nobody special, nobody famous or distinguished. I'm just another garden-variety practitioner.

For you to take exception to my comments, not because you disagreed with them, but because you found them emotionally unsettling, is, in my opinon, psychologically arrogant. I was going to write "intellectually arrogant", but I beleive that your reaction wasn't an intellectual act.


In my world, facts take precedence over all. We all have preferences, and I'd certainly prefer to die in bed, not in the cockpit. And I beleive I'm a hell of a lot more likely to achieve that goal by sticking to the facts as they are rather than as I might wish them to be.

In my opinion, a hell of a lot of the rest of human affairs would be greatly improved if more people adopted that attitude as well.

Last edited by LSLGuy; 06-07-2009 at 09:14 AM..
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  #37  
Old 06-07-2009, 10:40 AM
LSLGuy LSLGuy is online now
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Belated edit 90 minutes later ---

I sorta got on a tear there and exceeded the guidelines for GQ. I apologize.

What I should have said was closer to this:

...(as written to this point)...

Among the ranks of the tens of thousands of pilots who fly or flew big jets, I'm nobody special, nobody famous or distinguished. I'm just another garden-variety practitioner. Experts who know far more than I about the details could doubtless disagree here and there with the simplifications I made in my writing for an even less expert audience.

Others here have already provided links to reasonably reliable cites; certainly cites accurate enough for the purposes at hand; a laymens' rough outline of a complicated subject.

We'll never know exactly what experiences those people had; the dynamics are too complex to calculate even if we had the data. And the next broadly similar accident will have quite different details. But in the main, we can make some broad-brush statements about how things probably were / will be.

Last edited by LSLGuy; 06-07-2009 at 10:42 AM..
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  #38  
Old 06-07-2009, 11:34 AM
Huerta88 Huerta88 is offline
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Originally Posted by Broomstick View Post
Because if the airplane depressurizes suddenly at 35,000 feet you won't be able to hold your breathe (in fact, attempting to do so can result in lung damage). The pressure differential will take most of the air out of your lungs, and since the partial pressure of oxygen in the surrounding air is less than what is in your body oxygen will move from your blood stream to the surrounding air until those partial pressures equalize. In addition your adrenaline-soaked body will be using oxygen faster than usual. You see, when you hold your breath you aren't really going without oxygen, you're using what's stored in your lungs. If you didn't have that store, if, in fact, oxygen is being drawn out of your body, you don't have as much time before you black out.
This is one reason (not the only one, obviously) that finding somewhat-intact (gruesomely enough, but not surprisingly, the Brazillian navy has reported that it's unable to determine the sex of the three bodies most recently recovered) bodies is good news -- the lungs of a person killed by oxygen starvation/pulmonary trauma at 35k feet will look different to a pathologist than the lungs of someone who hit the water alive and drowned (and different I guess than someone who hit the water alive and, more likely, was killed by the impact). So a few clues will emerge.
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  #39  
Old 06-07-2009, 01:44 PM
The Great Philosopher The Great Philosopher is offline
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Originally Posted by LSLGuy View Post
Wow - where to begin ???

Broomstick - Thank you.

The Great Philosopher / OP: I regret that you have so thoroughly misunderstood my points.

I live in a fact-based world. I might prefer that milk and honey flowed freely in the streets and that all kids grew up in a safe environment with caring parents and material plenty. Sadly, I know the world doesn't work that way. Even though I'm not an expert in those areas, I know and accept that the world doesn't work that way, at least not today.

I believe that for me to crimp my eyes shut and choose to believe that all kids do have a great life is to do them a disservice. It removes me from the pool of people who can care, who can do something about it. It transforms me into a let them eat cake kind of person, at least passively, if not actively.


Almost nobody sensible wants to die. Nobody sensible wants to die unpleasantly. Nobody sensible wants others to die unpleasantly.

We do the dead a disservice, a disrespect, by blythely assuming they didn't suffer, or "never knew what hit them". In doing so we are choosing to close our eyes to their reality. Why do we do that? I submit that's because it's too unpleasant in our reality. Are we so weak we can't withstand merely thinking about what others are forced to actually experience? That is cowardice.

You asked us what it was like for those poeple. I have unflinchingly told you what, in my professional opinion, I believe it was like. And I believe it was not pleasant.

I am not an accident investigator, although I have in my professional capacity read many dozens of accident reports over the years. I have watched helplessly as men died in aircraft. Not on youtube; for real. There is a difference.

I am not an aero engineer, although I have in my professional capacity read many books on the practical application thereof. I have been trained, practised, and been exhaustively evalauated on both my book knowledge and my practical use of that knowledge.

Among the ranks of the tens of thousands of pilots who fly or flew big jets, I'm nobody special, nobody famous or distinguished. I'm just another garden-variety practitioner.

For you to take exception to my comments, not because you disagreed with them, but because you found them emotionally unsettling, is, in my opinon, psychologically arrogant. I was going to write "intellectually arrogant", but I beleive that your reaction wasn't an intellectual act.


In my world, facts take precedence over all. We all have preferences, and I'd certainly prefer to die in bed, not in the cockpit. And I beleive I'm a hell of a lot more likely to achieve that goal by sticking to the facts as they are rather than as I might wish them to be.

In my opinion, a hell of a lot of the rest of human affairs would be greatly improved if more people adopted that attitude as well.
I didn't find your comments emotionally unsettling, I just found them useless for answering my question - you just went off on a tangential rant, like you've done again here. You didn't tell me what it would have been like for the passengers, you told me two things: that violent turbulence can't render anyone unconscious (which is wrong) and that the passengers would 'guaranteed' have been conscious, which might well be true but you didn't justify it, and given that it contradicts what a number of other pilots and doctors have said, I feel it's a claim that needs to be justified.
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Old 06-07-2009, 01:58 PM
Broomstick Broomstick is offline
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I'm sorry, Philosopher, but I can't see where LSLGuy and the "other pilots and doctors" are in conflict here. Could you please point out, specifically where you see this contradiction?
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Old 06-07-2009, 02:15 PM
Musicat Musicat is offline
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My piloting experience is very limited, but the scenario that seems most likely IMHO, given everything we know about the crash so far, is that some of the instruments malfunctioned due to the storm (see the references to the pitot icing problems); the pilots and the automatic equipment didn't know which way was up and what their true speed was. This led to improper corrections, worsening conditions, and they lost control or the plane exceeded design parameters.

Just remember: that high, that fast, in a severe storm at night, you can't just look out the window to get your bearings, and you can't rely on your instincts to tell you which way is up, which way you are going or how fast. You are totally dependent on instruments. What happens if one airspeed indicator says you are going too slow, and the other says you are going too fast? What if one dial is "stuck," and says you are at a constant altitude but you are really heading straight down?

As an example, if the pitot tube was getting narrowed by ice accumulation, the apparent airspeed would be decreasing. If the tube was blocked, it would say you aren't moving at all. Let's say the pilot increased speed to conpensate and got hit even harder with the storm.

So to answer the OP, it was probably a nightmare until the plane broke up. Then it got worse.
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  #42  
Old 06-07-2009, 02:40 PM
The Great Philosopher The Great Philosopher is offline
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I'm sorry, Philosopher, but I can't see where LSLGuy and the "other pilots and doctors" are in conflict here. Could you please point out, specifically where you see this contradiction?
From the Daily Telegraph: "Experts said the most likely scenario was that the break-up was caused by massive depressurisation inside the plane ... As Philippe Juvin, a French doctor, explained: ďIf depressurisation is extremely brutal, you lose consciousness and a deep coma sets in. It would have been like falling asleep."

Hope that's 'specific' enough for you mate.
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  #43  
Old 06-07-2009, 03:50 PM
Broomstick Broomstick is offline
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Actually, if decompression is fast and extreme enough, you can be ripped apart, see Byford Dolphin. However, the pressure differential between an airliner and the atmosphere is not sufficiently great to generate that effect

Yes, if decompression is "sufficiently brutal" you can lose consciousness but it's not guaranteed. Testing of human subjects in altitude chambers reveals that there is a range of response in any group of individuals. Also, we don't know how "brutal" this decompression was, if it was fast or slow, if it had occurred before or after an airframe breakup.... There are MANY instances of people retaining consciousness during and after an airplane depressurization, in fact, I've even spoken with people who have directly experienced it. The effects vary with altitude, speed of pressure change, the individual, and so forth. It is not always "brutal".

Who are these "experts" quoted by the Daily Telegraph? What are their credentials? Who is this doctor? Does he have credentials in aviation medicine or experience with barotrauma? It looks to me like he's hoping that the people were knocked out, but did he know that? On what does he base that opinion? And it would be helpful if you linked to the original articles you took that information from so we can read them independently and fact-check them independently.

The only Phillipe Juvin I could find on the internet was this guy who, although he is a medical doctor, seems to function primarily in government and politics in France. He has been appointed to a health commission and another on Alzheimer's, and apparently has experience in anesthesiology and intensive care. My apologies for those who don't read French - I couldn't find much on him in English but I have tried to summarize what was in the French wiki. Indeed, in this reference he makes a response in a respected, peer-reviewed journal of anesthesiology discussing difficult intubation (that IS in English). All very worthy and wonderful things, however, nowhere do I see listed any experience in aviation-specific medicine, barotrauma, or even high-altitude medicine. In other words, he has no specific and specialized knowledge of the subject. I believe I found the quote you mentioned, but it was one sentence and potentially out of context, from someone with no particular expertise in the area being discussed. Oddly enough, he is not quoted in the French media, which makes me think this may have been a case of English-speaking reporters latching onto someone in France who looks official and speaks English. There is a LOT of coverage of Flight 447 in the French media, with quite a few official statements, but as I said, none from Juvin among the official statements.

You see, those of us who have been here awhile know LSLGuy as a professional pilot who flies "big iron", and a number of us know that those guys have to have specific training in regards to flying pressurized aircraft, including what happens when the system breaks down and what to do about it. I don't know anything about these people you say were quoted in the Daily Telegraph. Without further information I can't evaluate the quality of your sources. They may, in fact, be quite solid and prove some of us wrong but until I have more information I just don't know.
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Old 06-07-2009, 03:57 PM
hibernicus hibernicus is offline
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If the tube was blocked, it would say you aren't moving at all.
Is this correct? If so, the failure would be immediately obvious, and therefore much less dangerous. The way I was taught is that if the pitot is blocked, the airspeed indicator reading remains constant, unless you climb or descend. If you climb the static pressure reduces and the airspeed appears to increase, and vice versa.
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Old 06-07-2009, 04:33 PM
Apollyon Apollyon is offline
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I remember a time when I sat next to a nervous passenger who almost jumped out of his skin when the landing gear lowered. I reassured him that that was a GOOD noise
Another nervous flier here -- and I feel grateful to a fellow passenger some years ago who looked at his white-knuckled neighbour and quietly opined: "I like turbulence, it reminds me that there is something holding the plane up". (For some reason I found this reassuring and some blood managed to get back into my fingers).
Quote:
Originally Posted by LSLGuy
In my world, facts take precedence over all. We all have preferences, and I'd certainly prefer to die in bed, not in the cockpit. And I beleive I'm a hell of a lot more likely to achieve that goal by sticking to the facts as they are rather than as I might wish them to be.

In my opinion, a hell of a lot of the rest of human affairs would be greatly improved if more people adopted that attitude as well.
I do wonder if a number of the quotes that make the papers re. comforting unconsciousness prior to the impact make it there in order to reassure the readers rather than as solid medical opinion.
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Old 06-07-2009, 05:13 PM
The Great Philosopher The Great Philosopher is offline
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Actually, if decompression is fast and extreme enough, you can be ripped apart, see Byford Dolphin. However, the pressure differential between an airliner and the atmosphere is not sufficiently great to generate that effect

Yes, if decompression is "sufficiently brutal" you can lose consciousness but it's not guaranteed. Testing of human subjects in altitude chambers reveals that there is a range of response in any group of individuals. Also, we don't know how "brutal" this decompression was, if it was fast or slow, if it had occurred before or after an airframe breakup.... There are MANY instances of people retaining consciousness during and after an airplane depressurization, in fact, I've even spoken with people who have directly experienced it. The effects vary with altitude, speed of pressure change, the individual, and so forth. It is not always "brutal".

Who are these "experts" quoted by the Daily Telegraph? What are their credentials? Who is this doctor? Does he have credentials in aviation medicine or experience with barotrauma? It looks to me like he's hoping that the people were knocked out, but did he know that? On what does he base that opinion? And it would be helpful if you linked to the original articles you took that information from so we can read them independently and fact-check them independently.

The only Phillipe Juvin I could find on the internet was this guy who, although he is a medical doctor, seems to function primarily in government and politics in France. He has been appointed to a health commission and another on Alzheimer's, and apparently has experience in anesthesiology and intensive care. My apologies for those who don't read French - I couldn't find much on him in English but I have tried to summarize what was in the French wiki. Indeed, in this reference he makes a response in a respected, peer-reviewed journal of anesthesiology discussing difficult intubation (that IS in English). All very worthy and wonderful things, however, nowhere do I see listed any experience in aviation-specific medicine, barotrauma, or even high-altitude medicine. In other words, he has no specific and specialized knowledge of the subject. I believe I found the quote you mentioned, but it was one sentence and potentially out of context, from someone with no particular expertise in the area being discussed. Oddly enough, he is not quoted in the French media, which makes me think this may have been a case of English-speaking reporters latching onto someone in France who looks official and speaks English. There is a LOT of coverage of Flight 447 in the French media, with quite a few official statements, but as I said, none from Juvin among the official statements.

You see, those of us who have been here awhile know LSLGuy as a professional pilot who flies "big iron", and a number of us know that those guys have to have specific training in regards to flying pressurized aircraft, including what happens when the system breaks down and what to do about it. I don't know anything about these people you say were quoted in the Daily Telegraph. Without further information I can't evaluate the quality of your sources. They may, in fact, be quite solid and prove some of us wrong but until I have more information I just don't know.
Exactly. I have no idea if that Doctor Juvin guy is reliable, I never said he was. The point is I find it irritating when people like LSLGuy come into my thread and instead of answering the question make assertions like it's "guaranteed" the passengers would have been conscious for the whole experience - something which is by no means a consensus opinion - with no explanation or justification whatsoever, then rant about how I'm "psychologically arrogant" or something when I press him for explanation. That's useless to me.
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Old 06-07-2009, 05:45 PM
mangeorge mangeorge is offline
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Yep! GQ!
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Old 06-07-2009, 07:12 PM
Broomstick Broomstick is offline
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Originally Posted by The Great Philosopher View Post
Exactly. I have no idea if that Doctor Juvin guy is reliable, I never said he was. The point is I find it irritating when people like LSLGuy come into my thread and instead of answering the question make assertions like it's "guaranteed" the passengers would have been conscious for the whole experience - something which is by no means a consensus opinion - with no explanation or justification whatsoever, then rant about how I'm "psychologically arrogant" or something when I press him for explanation. That's useless to me.
Keep in mind that when LSLGuy goes to work he's gone for several days at a time with sharply limited access to the internet, if any at all. You may not be aware of that. This is a good thing, as he needs to be flying the jet while at work and not posting to The Straight Dope. Typically, he responds a little slower than the rest of us and may not be able to provide definitive cites until he gets back home. That's why sometimes the rest of us try to help him out though, of course, we also try not to put words in his mouth.

Anyhow, the Free Fall Research Page, linked to up-thread, provides evidence that people have fallen from great heights and survived, Vessna Vulovic currently holding the record at a 33,000 foot fall without parachute and surviving, riding the airplane wreckage down to the ground. Information on actual experiences of decompression and airplane break-up has been gleaned from numerous lucky survivors. Reports vary, with some claiming no memory of their fall and others providing considerable detail. For example, Lt. Col William Rankin bailed out of his military jet at 47,000 feet, lost his oxygen mask, but remained conscious for almost all of the subsequent 40 minute ride through a thunderstorm which carried him from Virginia to North Carolina.

In light of this, I see no reason to conclude either way that the people aboard Flight 447 were aware or unaware. Given the circumstances, there was probably a range of states of awareness between unconscious (or even dead) and fully cognizant of the situation. Some people might have, indeed, perished from heat attacks or a blow to the head. Others may have indeed been aware all the way down.

This is one reason why recovery of the bodies is seen as important. Injuries can reveal significant facts about the last few minutes of the flight and subsequent fall to the water. For example, true explosive decompression tends to cause lung damage that is revealed at autopsy. Slower decompression does not. Water in the lungs can indicate drowning, meaning the person was alive when they hit the water, perhaps even briefly afterward, whereas those who die at altitude will usually have lungs without water in them.

For example, the BOAC Flight 781 Comet break-up in 1954 pre-dated black boxes but the pattern of injuries in recovered bodies permitted reconstruction of the accident, and the distinctive lung damage indicated genuine explosive decompression that, combined with a violent break-up of the airplane, resulted in a case where people probably genuinely had no idea what hit them and really were dead before final impact. On the other hand, in 1961 the Yuba City B-52 crash the airplane was able to descend to 10,000 feet after decompression and, despite crashing due to lack of fuel, everyone aboard survived without injury.

What it comes down to is that each accident is unique, and it's impossible to definitively say whether the passengers were aware of the fina falll or not until an investigation is complete. In the past, both scenarios have been found to be true at different times.

Last edited by Broomstick; 06-07-2009 at 07:15 PM..
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Old 06-07-2009, 07:21 PM
Musicat Musicat is offline
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Originally Posted by hibernicus View Post
Is this correct? If so, the failure would be immediately obvious, and therefore much less dangerous. The way I was taught is that if the pitot is blocked, the airspeed indicator reading remains constant, unless you climb or descend. If you climb the static pressure reduces and the airspeed appears to increase, and vice versa.
Atually, I believe there are typically two tubes, one facing into the wind, so to speak, the other at right angles to it. The difference in air pressure between them can be used to compute the airspeed.

http://en.wikipedia.org/wiki/Pitot_tube
http://en.wikipedia.org/wiki/Pitot-static_system

If one or the other tube is not fully open, it would affect the readings. Whatever effect it might have is not good and might not agree with expectations or other instruments.
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Old 06-07-2009, 07:29 PM
Musicat Musicat is offline
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From one of the links I referenced above:
Quote:
A blocked pitot tube is a pitot-static problem that will only affect airspeed indicators. A blocked pitot tube will cause the airspeed indicator to register an increase in airspeed when the aircraft climbs, even though indicated airspeed is constant. This is caused by the pressure in the pitot system remaining constant when the atmospheric pressure (and static pressure) are decreasing. In reverse, the airspeed indicator will show a decrease in airspeed when the aircraft descends. The pitot tube is susceptible to becoming clogged by ice, water, insects or some other obstruction.
Here's an example of what may happen under these circumstances. The pilots thought the airspeed had dropped due to faulty instruments. A fatal crash was the result.

Last edited by Musicat; 06-07-2009 at 07:33 PM..
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