Re: Greek plane crash questions


"Ernie B." <ernie-baresch_REMOVE_@xxxxxxxxxxxxx> wrote in message
news:MPG.1d6ff132b56a421c98a821@xxxxxxxxxxxxxxx
> On Fri, 19 Aug 2005 14:29:47 -0400 Hooda Gest wrote:
>
> > My question would be: what happens when the airplane
> > > arrives at the destination with no further instruction? Does it
> > > enter a holding pattern or what?
> >
> > That's a good question. But let's assume, for the moment, that it
> > deactivates automatically on commercial airliners (it did not do so on
Payne
> > Stewart's flight a few years ago) now.
>
> Not a good assumption imo. Seems to me that the last thing you would
> want would be to turn the airplane loose and leave it to its own
> devices.

I agree. It should stay on and provide a warning at the destination point.

>
> > What took the plane south, circle
> > over the island of Kea, and then turn north again?
> >
> My guess would be that the autopilot was programmed to fly in big
> circles and await further instructions.

That would make some sense. Thinking about it, it would be logical that it
(the autopilot) would do this if there was no response to the alert at
destination. It also makes sense that there might be auto-routing to an
offshore area (decreasing chance of damage or loss of life on the ground
should the plane end up going down). But what turned it back north?

>
> > My common sensical take on an autopilot deactivating automatically is
that
> > you would not want that to happen it is an option the pilot could
choose.
> >
> Right. See above.
> >
> > I didn't make it. It took me more than 30 seconds the first time. The
> > second time I made and it took me about 13 seconds.
> >
> I made it at 35,000 ft. but it took several tries. Supposing that
> the pilots were current they should be able to do the real thing in
> five seconds or less ... IF they knew what was happening.

I chose 34000 because that is the altitude given in the story but it would
be quite possible for decompression to have occurred at a lower altitude.
Trained pilots should have been aware of what was happening. Warning lights
and some audible signal should have gone off. Plus, a trained pilot should
recognize the physical indications.


> >
> > If there was a couple of people moving about in the cockpit, who were
they
> > and how did they get in?
>
> Non-pilot passengers?

Maybe but why were they alert and able to move when the crew, trained one
assumes, wasn't?

> > Perhaps the airline had not instituted the
> > strengthening of the cockpit door.
>
> The crash axe would get into the cockpit. Question is: Now that I'm
> here, what do I do?

I wouldn't know where to look for such a thing. But how am I moving about
this decompressed cabin without portable oxygen?

>
> > Or maybe the pilot is one of the people
> > seen.
>
> Doubtful. If the pilot were there he would have been on oxygen and
> have started a rapid descent.

You would think.

>
> > I can imagine the pilot falling out of his seat and collapsing or
> > being elsewhere on the plane at the time of the decompression.
> >
> Yep, when he passed out.
> >
> > That's possible but that should be the "norm".
>
> How so?

Decompression caused by leaks or equipment failure should be gradual,
relatively speaking, unless a big hole is blown in the hull.

>
> > The oxygen masks are
> > triggered when cabin pressure falls to a certain level, I would think.
>
> When it falls to 12,000 ft. usually.

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/08/16/MNGVAE8CRS1.DTL

Airplanes that fly higher than 10,000 feet are pressurized because air at
that altitude is too thin to breathe. Air is drawn into the engines and
compressed, then released into the cabin to maintain the atmospheric
pressure found at 8,000 feet.

The pressure inside the cabin is called "cabin altitude." Should cabin
altitude rise to 10,000 feet, an alarm warns the pilots, who put on oxygen
masks and dive to 10,000 feet -- where passengers can breathe without oxygen
masks.

When cabin altitude rises to 14,000 feet, oxygen masks above each passenger
are deployed. Passengers receive about 10 minutes of oxygen created by
generators; pilots can descend to safety from a cruising altitude of 36,000
feet within 2 1/2 minutes, experts said.

(the above is another look at the Greek incident)

>
> > A
> > slow loss of pressure would provide more time to react than less. It's
the
> > rapid loss that seems to be the big problem.
> >
> But a slow loss of pressure tends to put people to sleep as the cabin
> pressure decreases, especially if they aren't familiar with their
> symptoms of hypoxia.

Right but a trained crew would be aware, wouldn't they? Still, I see your
point. I am sensitive to pressure (ear thing) so I notice very subtle
pressure changes when flying. In the 60s and 70s, cabin pressure was not
nearly as well maintained as it is today and I suffered greatly.

Still, I recall a trek up to Sandia Peak outside of Alburqurque back in
1977. I thought everything was fine until I started climbing stairs from the
lower parking lot to the observation platform and tourist center. 20 steps
and I was wheezing like a full blown asthma attack.

Also, from the above url I provided...

"Such symptoms come on more slowly at lower altitudes or if the plane
depressurizes slowly because of, say, a poor seal in a cabin door, experts
said."



>
> > Here's some info on Stewart's crash that might be useful or might not
apply
> > to commercial flights.
> >
> > http://www.ntsb.gov/Publictn/2000/AAB0001.htm
> >
> Interesting. The airplane was built in 1976, my guess would be that
> the autopilot would be fairly simple compared to those of today, with
> functions including altitude hold and heading hold.

Whatever happened on that plane happened quickly. But, as Fred pointed out,
a private charter business jet is a different animal.

>
> > Still, the last words in the article are interesting...
> >
> > Tsolakis has he has never encountered such a case. ``In my career, going
> > back 50 years as an airman and as a safety officer, I have never seen
> > anything that resembles this,'' he said.
> >
> The things that you haven't seen before are the ones that will bite
> you. :-(


Every time.


--
Hooda Gest
"Respect is difficult to win, easy to lose."

.

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