O2 and Cypriot airliner crash

Tom wrote:
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

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

Tom,

I'm aware of the points you make and have been for (more than three)
decades. It doesn't make the recent posts any more the right way to
approach the subject, especially considering the distress it would cause
some who might read it.

But, in a way, I suppose you're right. _My_ expectations of people _are_
probably way too high.

Rgds,

Derrick Steed

CO2 is generated by cellular respiration. This is essentially
independent of oxygen, as a matter of fact, anaerobic respiration can
occur in the absense of adequate oxygen, but it is VERY inefficient, and
makes LOTS of waste products.

Arterial CO2 concentration, having left the lungs, is around 35-45 torr
(mmHg). In mixed venous blood, returning to the lungs, it is around 50
torr/mmhg or so.

At sea level, atmospheric CO2 is in the high 20's/low 30's mmhg. The
body's buffer system in a healthy individual will RAPIDLY move the CO2
level back towards normal if it vary's too much from those values. So,
even at altitude, your venous blood gas values are pretty much normal
after one pass around the body. You hold your breath, and this blood
with "venous" levels of CO2 will make a second pass, and when it hits
the chemo and baro receptors in in your carotid (artery) bodies you will
start getting that URGE to breath.

All of this is independent of how oxygen is handled by the blood. Each
gas's function in the body is more or less independent of each other.
Even though your body uses oxygen to make CO2 as a waste product, your
body will continue to make CO2 for a short time without adequate oxygen.
As an example: the burn in your muscles after a sprint - lactic acid
generated along with CO2 when the oxygen requirement of the muscles
outstrips the oxygen supply.

To say "the lungs stop working" is at best, technically inaccurate. You
are just too hypoxic to make the muscles responsible for gas exchange to
work properly.

Dave

In article %N5Me.1542$yb.46@trndny01,
George Patterson wrote:

Because of this, the FAA requires that a pilot use oxygen if they
spend over 30 minutes above 12,500'.

My recollection of my O2 training is that the rule is 30 minutes over
10,000 ft, or if you go over 12,500 ft at *all*.

But I've only been to about 20,000 ft in a glider, unlike some people I
know who have been far higher.

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------

"Bruce Hoult" wrote in message
...
In article %N5Me.1542$yb.46@trndny01,
George Patterson wrote:

Because of this, the FAA requires that a pilot use oxygen if they
spend over 30 minutes above 12,500'.

My recollection of my O2 training is that the rule is 30 minutes over
10,000 ft, or if you go over 12,500 ft at *all*.


Is that cockpit pressure or actual altitude??

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

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

I flew a glider to over 29,000 feet with an A-14 diluter demand system and a
pulse oximeter. It showed a solid 98% SpO2. I have flown to more than
38,000 feet with an A-14 and felt fine but I didn't have a oximeter.

The military systems like the A-14 are good to 38,000 feet according to the
manuals. Above that, a pressure demand system is needed like the US Navy A1
or the USAF A15 with matching pressure demand mask. The pressure demand
system is good to over 50,000 feet, again according to the manuals. The US
Navy A1 system manual specifically says normal SpO2 to 55,000.

Note that a pressure demand mask is very hard to breathe through below about
20,000 feet because of the effort to work the double check valves.

Bill Daniels

Bruce Hoult wrote:

My recollection of my O2 training is that the rule is 30 minutes over
10,000 ft, or if you go over 12,500 ft at *all*.

No. 12,500' if you exceed it for 30 minutes or 14,000' if you go over that at
all. At 15,000', passengers also have to be on oxygen. Section 91.211.

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.

fred wrote:

In article %N5Me.1542$yb.46@trndny01,
George Patterson wrote:

Because of this, the FAA requires that a pilot use oxygen if they
spend over 30 minutes above 12,500'.

Is that cockpit pressure or actual altitude??

Cabin pressure altitude.

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.

"Bruce Hoult" wrote in message
...
In article %N5Me.1542$yb.46@trndny01,
George Patterson wrote:

Because of this, the FAA requires that a pilot use oxygen if they
spend over 30 minutes above 12,500'.

My recollection of my O2 training is that the rule is 30 minutes over
10,000 ft, or if you go over 12,500 ft at *all*.

Better review the rules;

Mike
MU-2

On Tue, 16 Aug 2005 02:44:54 GMT, George Patterson
wrote:

Bruce Hoult wrote:

My recollection of my O2 training is that the rule is 30 minutes over
10,000 ft, or if you go over 12,500 ft at *all*.

No. 12,500' if you exceed it for 30 minutes or 14,000' if you go over that at
all. At 15,000', passengers also have to be on oxygen. Section 91.211.

This is all irrelevant if there is no oxygen in the system. That'd
be my guess. Too much trouble to check or refill. Tanks at the
airport are empty. Somebody sold them to a welder . . . .

Don

George Patterson wrote in
news:GqcMe.161$zb.155@trndny04:

Bruce Hoult wrote:

My recollection of my O2 training is that the rule is 30 minutes over
10,000 ft, or if you go over 12,500 ft at *all*.

No. 12,500' if you exceed it for 30 minutes or 14,000' if you go over
that at all. At 15,000', passengers also have to be on oxygen. Section
91.211.

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.

Almost, but not quite correct.

91.211a(1,2) says "...flight crew is PROVIDED WITH AND USES (emphasis mine)
supplemental oxygen" at the 12,500 and 14,000 foot altitudes as you
correctly noted.

91.211a(3) says "...above 15,000 feet (MSL) unless each occupant is
PROVIDED WITH supplemental oxygen." Your passengers are never required to
be USING oxygen.

Yes, it's a minor point...
-Bob Korves