See the link first, as usual; you’ve all heard about this…
http://www.cnn.com/2000/US/11/20/emergency.landing.02/index.html
Two points:
Why is the cabin pressurized more than the ambient pressure at nearly sea level, in Miami? This makes no sense to me.
Even more important, on every jet aircraft I’ve ever flown on, the doors open INWARD, to prevent just such a catastrophe (but admittedly in mid-air)! How can something like this happen on the GROUND?
See also http://www.washingtonpost.com/wp-srv/aponline/20001120/aponline151656_001.htm
Re question. You “get sucked out” due to pressure differentials. If you are standing in just the the right(ie wrong) spot whether doors open in or out you can still get pulled out.
As to why plane was still pressurized on ground… WAG - IIRC per my last plane trip some planes are de-pressurized as they taxi in. There was apparently some sort of engine fire warning and this might have prevented normal de-pressurization (assume it is controlled via pilots in cockpit) procedures either because of oversight or some sort of safety protocol in those circumstances.
I’m no expert here, but keep in mind what was going on at the moment. The plane got a pretty serious warning light about its engine being on fire and swiftly descended and landed.
There is probably a set amount of time that the cabin needs to safely depressurize. Most times, you never have a problem with it because your not in this much of a hurry to get off the plane.
In this case, it all happened very fast and very unfortunately for the happlass steward.
I would not have thought that in normal ops the cabin would ever be pressurized greater than sea level so you would not normally have to depressurize. My guess would be that the system that maintains cabin pressure at altitude was left on during descent thus over-presuurizing it.
I fly (helicopters) with the doors off, so I don’t know much about when the cabin is pressurized and depressurized. I also only heard a brief line of two about the incident in question. I haven’t read the link yet. So here’s my WAG:
In an emergency let-down, perhaps depressurization was a minor issue. (Although I’d want to have the pressure equalized so that the emergency egress points could be used immediately.)
Semantic quibble: Aren’t things blown (not sucked) out of an aircraft in a rapid decompression? (High pressure flows into low pressure.)
From what I gathered, the pressure differential wasn’t so huge that the steward was literally “whooshed” away. I got the impression that he was probably a little off-balance, right at the door, and the small push (or pull) was just enough to make him loose his balance and tumble out. The fall from that height onto the tarmac killed him. I didn’t picture a huge inrush (outrush?) of air when the door was opened, but just a small push that was just enough to knock him off-balance and out the door.
Arjuna34
I agree with Arjuna. I can’t believe that air pressure had anything to do with it. Airline doors are “beveled” (sort-of), open inward, then swivel, and then can be manuvered outside the fuselage. Any cabin pressure would’ve been immediately released when the door was popped open.
The amount of pressure required to suck someone out would’ve required that the cabin be pressurized to such a degree that, when immediately released, would’ve probbably given all the the passengers the bends.
I’m quite fond of the letter “b”–sometimes too much so.
“probably”
That’s FLIGHT ATTENDANT, thank you.
hahahahahaha
In the Airbus to which this happened (I’m told), the doors open outwards. The pressure differential caused the door to swing outwards with enough sudden force to toss the steward (who couldn’t let go of the handle quickly enough) out of the plane, where the fall killed him.
I thought planes were always at a lower pressure internally than they would be at sea level. What’s the point of overpressurizing a plane? Yes, we fly in pressurized cabins but the pressure in a plane would be something like the pressure at 10,000 feet. Anyone ever notice their feet swell some on an airplane? This is from pressure being lower than you are used to…not higher. Keeping a higher pressure just puts stress on the airframe to explode as the pressure drops outside. At the most you’d think they’d just pressurize to sea level and leave it at that. Being that Miami is essentially at sea level I can’t see how this’d be an issue.
So, if the pressure is LOWER on the inside of the plane then air should whoosh IN when opening the door…not whoosh OUT. In that case the attendant should have been knocked back into the plane.
The only thing I can figure here is that the pilot intentionally overpressurized the plane to keep smoke out if there was a fire. That’s just a WAG and it doesn’t sound all that plausible even to me but why else would this happen?
There’s oddly little detail about this incident on my usual Web sites. The most informative, and this is below their usual standards, is Aviation Week. Even AA’s own press-release list has nothing substantial. The name of the poor guy (who was the purser, the head FA on the flight) was released earlier today. His name was Jose Chiu, and he lived in New York. The plane was an Airbus A300.
I suspect Arjuna and Hansel are right in their supposition about how Mr. Chiu lost his balance. If the pressure delta had been all that much, he couldn’t have opened the door (which does initially swing inboard) at all.
I won’t try to guess why the cabin pressurization wasn’t shut off during descent. Certainly the crew had their hands full flying on one engine. I’ll keep tracking AvWeek and see if anything useful comes up.
I agree with Jeff_42. I have never heard of a plane being pressurized to beyond sea level. Here is a link that states that the Airbus A300 is pressurized to 800 millibars during parabolic flights for microgravity experiments. I know this link alone doesn’t prove that the Airbus couldn’t be highly pressurized at other times. But I would like to see a cite before I will believe it.
My best guess is that the attendant simply stumbled out in a manner that nothing to do with air pressure.
I flew on an airbus last Wednesday night (and Delta was kind enough to upgrade me. Travel agent perk.). Anyway, sitting up front, I was first in line to get off. I watched as they opened the door, since I’ve always been curious about it. That’s where I noticed the “beveled” shape of the door.
The door opened inward, pivoted, and then was able to be pushed outside the cabin. I can’t see any way that air pressure could’ve contributed at all in making somebody fall out.
Who knows? Maybe the doors can be operated in a different manner in an emergency?
According to the NTSB report: http://www.ntsb.gov/aviation/mia/01a029.htm , the whole reason for returning to Miami was a problem with the pressurization system. According to witnesses, the door “exploded open” as the crew was preparing to evacuate the plane because of fire. It says it was the left front door (the one you board & deplane through), so I have no idea why it wouldn’t operate like all airliner doors I have ever seen (swing in, swivel & swing out).
The pressurization system operates by bleeding air off of the compressor section of the engines. If it was not operating properly (and it was not), it could overpressurize the cabin, instead of maintaining a minimum pressure equal to about 8,000 ft above sea level.
To Jeff_42: I don’t think swollen feet have anything to do with the slightly lower pressure. It has to do with sitting for hours, without significant muscle activity in your legs to prevent edema. The same thing will happen when you sit through a long movie without getting up. It is suggested that you get up and stretch your legs every couple of hours. This will help prevent blood clots in your legs that can travel to your lungs & kill you.
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Hi fellow Longhorn! Hook 'em!
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