O2 and Cypriot airliner crash

"pbc76049" wrote in message
...
Most passenger O2 systems use chemically generated O2.
There are no bottles to check. There are cabin walk around bottles
and the flight deck is bottled O2, but passengers are not. Remember
the Valujet crash. The initiating event was a cargo bay/cabin fire casued
by
improperly shipped O2 generators igniting in flight.


Even if the passengers have chemically generated O2, the pilots have O2 from
a bottle. Pilots are required (and most do) check their O2 before take-off.
The chemically generated O2 units cannot be turned off once in use and then
must be replaced. Therefore pilot positions have bottled O2.

Duane

On Mon, 15 Aug 2005 18:36:13 UTC, T o d d P a t t i s t
wrote:

: "Ian Johnston" wrote:
:
: Oxygen is only part of it. The breathing reflex is triggered by the
: carbon dioxide partial pressure in your lungs: when atmospheric
: pressure falls below that you never get the trigger and your lungs
: just stop working. This is a Bad Thing.
:
: Your lungs work OK, but there's not enough O2 to keep you
: conscious. ...

Thanks.

: Of course, at high altitudes, if the PP of CO2 is so low
: that your body fails to breathe, then that can cause of
: death, even if the PP of O2 would be high enough to keep you
: alive.

That's what I ws thinking of. Doesn't that effect kick in about thirty
something thousand feet?

Ian

At 19:12 15 August 2005, George Patterson wrote:
wrote:

Any thoughts or corrections to my reasoning?

The ATP is correct. While people do vary greatly, and
some people have been able
to perform adequately without oxygen at 20,000' or
more, most people can't go
much higher than 10,000' without suffering some ill
effects. Because of this,
the FAA requires that a pilot use oxygen if they spend
over 30 minutes above
12,500'.

In general, people can use a cranula or similar device
to provide oxygen up to
about 20,000' (the FAA limits use of these to 18,000').
These simply bleed
oxygen into the air you breathe. Above that, you need
a low-pressure mask. These
ensure that all you are breathing is oxygen and are
good up to about 25,000'.
Above that, you need a pressure mask. Those increase
the pressure of the oxygen
and work well up to about 35,000'. Above that, you
need a pressure suit or a
pressurized aircraft.

The emergency drop-down masks for airline passengers
are low-pressure. They
won't keep you conscious at 35,000', but they may keep
you alive.

George Patterson
Give a person a fish and you feed him for a day;
teach a person to
use the Internet and he won't bother you for
weeks.

The pilots however are provided with pressure masks

"Ian Johnston" wrote in message
wrote:
: Of course, at high altitudes, if the PP of CO2 is so low
: that your body fails to breathe, then that can cause of
: death, even if the PP of O2 would be high enough to keep you
: alive.

That's what I ws thinking of. Doesn't that effect kick in about thirty
something thousand feet?

It starts at about 14,000 feet. People sleeping above this altitude can
suffer a condition called "Periodic Breathing". This is a cycle of
breathing until CO2 levels drop (the body enters a state of alkalosis), then
breathing stops, CO2 levels rise, the body responds by gasping and
hyperventilating and then stops breathing again. As altitude goes up, the
effect becomes nastier. And a bunch of other bad things become a looming
possibility.

le m

This is a message to Andy Kirkland: one thing is VERY apparent to from
the current thread about the Cypriot airliner, that relating to the
HusBos fatality, and the Nimbus 4 and big wings discussion, and that is
that most subscribers to this group suffer from a morbid fascination
with speculation about tragic accidents with scant regard for the
feelings of those who may have been directly affected by them.

Wouldn't it be useful to have a group for the sole purpose of
discussions relating to the type of morbid speculation and various
exchanges of ignorance that we are currently being subjected to?

Now, where did I put that fireproof suit?

Rgds,

Derrick Steed

"T o d d P a t t i s t" wrote in message
"Ian Johnston" wrote:

: Of course, at high altitudes, if the PP of CO2 is so low
: that your body fails to breathe, then that can cause of
: death, even if the PP of O2 would be high enough to keep you
: alive.

That's what I ws thinking of. Doesn't that effect kick in about thirty
something thousand feet?

It's no lower than that, and is typically higher. I'm not
sure of the actual point.

That the breathing response is diminished? It starts much lower. But the
rest of your post indicates that you agree with that.
I've been through the
FAA/military oxygen training 3 times and I've flown to 30K'
in a glider on 100% diluter demand O2. I was breathing
deeply and carefully under conscious control, not relying on
my breathing reflex.

That's a real feat. Without acclimatisation training, which, among other
things, increases hemoglobin counts, it's hard to stay usefully awake after
a rapid ascent to that altitude. If you used an oximeter, I'd be interested
in the readings. Did you notice any of the usual effects of hypoxia?

moo

George Patterson wrote:


In general, people can use a cranula or similar device to provide oxygen
up to about 20,000' (the FAA limits use of these to 18,000'). These
simply bleed oxygen into the air you breathe. Above that, you need a
low-pressure mask. These ensure that all you are breathing is oxygen and
are good up to about 25,000'.

My understanding is cannulas are still effective to at least 25,000',
and the FAA mask requirement is only to guard against pilots that might
inadvertently breathe through their mouth instead of their nose. The
masks I've used all allow ambient air into the mask; i.e., they are not
intended to supply only oxygen. They used staged valves for constant
flow systems, or just small holes in the sides of the mask for
pulse-delivery devices like Mountain High's EDS controller.



--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Derrick Steed wrote:

one thing is VERY apparent to from
the current thread about the Cypriot airliner, that relating to the
HusBos fatality, and the Nimbus 4 and big wings discussion, and that is
that most subscribers to this group suffer from a morbid fascination
with speculation about tragic accidents with scant regard for the
feelings of those who may have been directly affected by them.

Todd Pattist Wrote:
I've posted in all three of those threads, and feel neither
a morbid fascination, nor any desire to speculate about the
actual causes. Nor do I see those characteristics in other
posters. I do see a desire to understand and prevent
accidents and I wonder how far you would go to prevent
safety discussions.=20

AFAIK, no one here is directly connected to the Cypriot
airliner accident, but many of us do face the dangers of
high altitude oxygen flight. The report on the Nimbus 4
accident was issued long ago, and the discussion seemed to
be about whether using airbrakes is advisable during
recovery. Don't you think that discussion is helpful? When
would you allow it here?

As to the HusBos accident, I understand your feelings, but
ultimately believe that trying to understand an accident is
the only way to prevent it from happening again. I think we
owe that to both those who died and those who might yet
live.=20

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~

Todd, I'm not complaining about the discussion of safety issues. I
welcome that and other discussions of a technical nature which foster a
greater understanding of our sport and how to be good at it while
maintaining safety. I find such discussions to be interesting and
sometimes educational and if I were to see these discussions continuing
as a reasonable level great, However, a trawl through the posts on this
group over the past year or so reveals the following: a) long periods
with nothing much about (for instance) safety being said, b) following
the occurrence of some notable event (especially those relating to some
accident) there is a burst of discussion relating to the factors which
may or may not have contributed that accident. It's like looking at an
attack and decay curve: incident happens, rapid escalation of discussion
on that topic, discussion dies down, another incident occurs, rapid
escalation of discussion, etc...

What I find objectionable is that in case (b) one is then subjected to
the spectacle of various personal agendas being vented on a soapbox
(supposedly) justified by the occurrence of the event being discussed.
There was the HusBos spinning accident - a long burst of discussion
ensued as a result with various theories and personal analyses of the
incident being put forward prior to any factual report of what actually
occurred (I had personally known for some years and had flown with the
instructor concerned some months previous to that tragic event), then
there were the Nimbus 4 discussions, then the latest HusBos incident,
lastly the airline crash (this is not a complete list I'm sure). In each
case there was an absence of any previous discussion relating to the
topic for some considerable time preceding the event - then, the event
occurs and, all of a sudden, soapboxes are rolled out, the analysis
begins, and the various correspondents put forward their version of
events (amazing considering most of them were not even there!).

In all of the discussions referred to, various opinions were shared with
the group, some valid, many inappropriate given the proximity of the
event and the need for an objective investigation to be carried out, not
to mention the involvement of the authorities and the due process of
law.

I just wish sometimes that we could collectively display a little
sensitivity and hold off on these discussions until the facts are known,
then discuss the pros and cons. I don't see that it is that urgent that
the discussions take place immediately, especially considering that the
same topics have come up again and again with little prospect of
agreement (and note that each time they come up, it is in response to
the occurrence of some incident).
=20
Rgds,

Derrick Steed

"Stewart Kissel" wrote in
message ...
Also, many of the high-altitude climbers who do not
use oxygen have shown significant brain damage when
cat-scanned.



Before or after climbing without O2?

--
Geoff
the sea hawk at wow way d0t com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

Derrick,
We (people) have a very short memory when it comes to many safety
issues. Wouldn't it be nice if the highway authorities left auto
wrecks on the side of the road for a few days or weeks to remind us of
how dangerous driving is?

When an unfortunate event occurs, it reminds some of us of our
mortality. Confronted with that, a portion want to talk about their
fears and concerns.

Consider a ground level railroad crossing. Pretty dangerous if you
ignore the signals, but after a while people get complacent and
actually even stop on the tracks due to traffic congestion. Then
someone gets hurt or killed and an uproar wells up to have a bridge
built. After a few weeks it dies down and life goes on. A few weeks
later, we again see people stopped on the tracks...

Fortunately, in aviation we don't have too many of these folks who stop
on the tracks. We generally have experienced pilots doing something
that confounds (some of) us. So we talk it out and try to explore all
the ways WE might get into and out of the same situation. We're not
always analyzing the specific accident, rather we examine the
circumstances that have been brough before us and how we might deal
with a similar situation.

-Tom