Depressurized 737 Crash Cause Found

[Pangloss]

This was the crash that happened in Greece, where the plane depressurized at altitude and everyone was knocked out or died, and the plane flew around on autopilot and eventually crashed. It looks like they've put together a timeline of what happened. It's not pretty.

 

As with many accidents, there were a number of factors working in conjunction. Veteran pilots sometimes refer to this as the "three strikes" rule -- the idea that it's almost never a single factor that causes an accident, but rather a tragic combination of mistakes. The surprise here is the human factor that turned what should have been a minor maintenance mistake into a complete disaster.

 

To summarize, apparently what happened is that the plane had maintenance work the night before, and the ground crew left open a valve, basically making it impossible for the plane to pressurize. This should have been detected by the flight crew prior to departure, as soon as the door was closed, but it was not. The valve could have been closed at any time during the flight.

 

As the plane climbed out of takeoff, the autopilot was set. At 10,000 feet, a horn sounded to indicate that the plane had not pressurized. Unfortunately, the crew misinterpreted the horn as the one that indicates that their takeoff controls are not set properly. The autopilot was not disengaged, and the plane continued its programmed climb.

 

Around this time, the pilot and copilot realized that they did not speak the same language.

 

No, really.

 

Apparently they'd never flown together before, and neither spoke very good English, their only common tongue and the official language of aviation around the world. They spent the next few minutes trying to communicate with each other.

 

When the plane hit 14,000 feet, the next programmed event in the event of no pressurization occurred -- the oxygen masks dropped from the ceiling. This apparently lead to a great deal of confusion, probably spurred by the fact that the flight crew would have been rapidly becoming very disoriented at this point. The pilot apparently got up to fix a minor problem that was not critical to the aircraft. And they continued on like this, not solving the problem, until they all passed out.

 

At some point the flight attendents realized something was wrong, and apparently broke into the cockpit. Blood was found in the cockpit belonging to one of them. Obviously their efforts, whatever they were, were not successful.

 

Because the autopilot was working just fine (in fact the entire airplane was working just fine), the plane continued in its programmed assent to 34,000 feet, killing most of the passengers along the way. Eventually it reached its programmed destination, and entered a programmed circling pattern (not being programmed to land, which it is capable but not normally designated to do, because the pilots have to get instructions and wait in line behind other planes). It circled until one of the engines ran out of fuel, disengaging the autopilot automatically, and the plane gradually lost altitude, eventually crashing into a hillside.

 

The blame game has already started, with Cypriot authorities blaming Boeing. The horn that sounds to indicate lack of pressurization is the same as the one used to indicate that flight controls are not set properly. But a properly trained crew should have known that that warning only sounds while the plane is on the ground -- in the air it means lack of pressurization.

 

Google News has several stories on this, so try this link for a list:

http://news.google.com/news?hl=en&ned=us&q=cockpit+confusion&btnG=Search+News

[Hellbender]

Wow. What a tragic series of screw-ups.

Blood was found in the cockpit belonging to one of them.

Odd. Any idea of how this blood came to be drawn in the first place? For that matter, what became of the pilot and co-pilot before they crashed?

[Pangloss]

Unknown. One guess would be that the attendant was injured while trying to force entry into the locked cockpit.

 

Regarding the pilot and copilot, the copilot was in his seat, and the pilot was not.

[Phi for All]

With all the redundancy in modern aircraft controls, I find it hard to believe that a horn was the only thing warning the crew that the plane was not pressurized. Aside from the oxygen masks dropping down, wouldn't there be at least a light flashing to let them know they shouldn't climb any higher? I can see where a system that wouldn't allow the plane to reach higher altitudes if the plane wasn't pressurized could be dangerous, but a single horn system of warning for something that life-threatening seems ludicrous.

 

There's not much time once they take off before they reach a lethal altitude. I've also heard of flights where the oxygen masks were deployed due to a malfunction that wasn't serious, so they may not have taken that warning seriously enough. Overlooking the fact that the horn sounds for improper flight controls only while on the ground was the big mistake here, imo.

 

What a tragedy.

[Pangloss]

Yeah, I suspect there are a number of indicators, not the least of which is the pilot's physical experience, both present and past. When you go from sea level to high altitude in a short time you should notice a vast change in the environment, even if the heaters are maintaining a constant temperature. Ears popping, for example.

 

More to the point, passenger jet pilots are trained on the importance of cabin pressurization from Day One. They understand the importance of it, it's very high on the list of "things that can go wrong", and should therefore be a high enough item on their mental checklists to consider that possibility long before they reach an altitude where they can no longer do anything about it.

[H2SO4]

It is realy sad. Youd think the palne would have a mechanism to close the valve after a certtain altitiude (becuase, as stated above, it can be closed in flight, so its obvioulsly electronc/hydraulic.

 

 

I hate flying. The fact that the plane has so many parts and your completely helpless scares the shit out of me. And to think this summer i fleww across the united states (ohio and indiana) 4 times.

 

 

 

It seeems there are alot of recent plane crashes. What the hell!?

[BobbyJoeCool]

It seeems there are alot of recent plane crashes. What the hell!?

 

That's because ALL of them get news coverage. Flying really is the safest way to travel, because it's the only way to travel where the driver (pilot in this case) has gone thorugh years of serious training and testing to be in control AND their's a co-pilot for in case something happens to the pilot. The Co-Pilot is not some lacky who's learning how to fly for the first time, (s)he's a trained pilot who just hasn't had the experience the pilot has, and is getting some experience flying.

 

How many flights take off and land without incident every day? How many crashes are there? one-two a month. Do you know how many boats sink, or trains de-rail, or the kicker... How many car accidents there are in that amount of time? You're MUCH more likely to die (or be seriously injured) in your car on the way to the airport than do die on the plane.

[Morpheus]

Don't you think since that you are in charge of driving a car that you will be able to kill the other driver instead of killing yourself?

 

Can someone do that with planes?

[BobbyJoeCool]

Don't you think since that you are in charge of driving a car that you will be able to kill the other driver instead of killing yourself?

 

Can someone do that with planes?

 

Suddenly remember's 9/11...

[celeste272]

That isnt what happened.

in them planes to pressurize the cabin they need to swith it to on. in theyre case they didnt. it should usually be switched to on by the engineer u are right and as part of the flight decks pre flight check they are meant to double check that it is inface switched to on. obviously in this instance they missed it... when they heard the horn they were well aware that it was infact the pressurization horn and they were advised by atc to turn around... but they did not. they kept climbing thinking it would be ok... now at 14 thousand feet the oxygen masks fell becoz that is the way the system is.. however there is no indication on any plane even untill this day in the flight deck that oxygen masks have infact fallen. it is cabin crews job to inform the captain. now at this point the captain and first officer were trying to fix the problem but due to the lack of oxygen other wise known as hypoxia they were clueless... they did speak the same language.. it was just they didnt know what to do... they were going through manuals and in touch with atc constantly but again, due to hypoxia... they were confused them self... this is why it is up to the cabin crew to inform the flight deck.. had the cabin manger told the flight deck.. they too would have put on theyre oxygen masks and would have been able to land the plane safely. however it took 2 hours for cabin crew to talk to go into the flight deck. there was no blood they were just unconcious and dead. the 2 cabin crew replaced theyre oxygen bottles with the flight decks and were trying to figure out how to atleast communicate. but becoz they were not on the right frequency they were unsuccessful. greece sent two fighter jets to the plane as they thought it was a terrorist attack. they reported seeing two cabin crew trying to fly the plane and the flight crew were incapacitated. they circled and circled untill they eventually ran out of fuel and then the plane came to a crash.

 

in my personal oppinion it was the flight decks fault for not turning around after being advised over and over.. but when they didnt it was up to the cabin crew to inform the pilot that oxygen masks have fallen and that they needed to drop to a safe flying distance. it had nothing to do with boeing. it was the fault of the crew unfortunetly. it is a horrible and sad story and one that as you said.. could have been so easily advoided

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the flight crew were suffering from hypoxia and couldnt work out what to do. it is the same on every flight and many captains do over look the pressurization switch during theyre pre flight checks.. because obviously when the plane is on the ground it cannot be pressurized it should be always on automatic.. but some times the engineer keeps it on manual. it has happened with alot more flights than u think.. however flight deck have just realised the error.. or after the oxygen masks have fallen cabin crew informed the flight deck straight away because there is no indication in the cockpit to say that the cabin oxygen masks have droped

[Fuzzwood]

That system can be, and will be as it is a step of the normal operations procedure checklist, switched to automatic, if not already on there.

[iNow]

Yes. It's amazing how much more we can know after 4 years.