Yrys
Army.ca Veteran
- Reaction score
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Nothing new in the article, I presume, for most folks, except maybe the 3min 30s video
Altitude and that woozy feeling
"I'm in a simulated altitude chamber under the watchful eye of Des Connolly of QinetiQ's Human Performance division,
and they're about to suck most of the air out.
It's all perfectly safe - for much of my simulated journey into the skies I'll be wearing a mask that provides air, much like
the one fighter pilots wear. But for four minutes, I'll drop that mask and see how it feels to breathe the thin air at
7,600 metres (25,000 feet).
QinetiQ carries out such tests on fighter pilots to instruct them on the effects of hypoxia, or oxygen starvation. They also
use the chamber to test life-support systems for high-flying jets such as the Typhoon, systems which are designed to
whip into action in the event of sudden depressurisation.
The symptoms are mild, and they rob the mind of the ability to reason, so if it sneaks up on you, hypoxia will have you
unconscious and then dead before you notice a thing. At the altitudes that a Typhoon can fly, that time could be as little
as five seconds. Luckily, I've got physiologist and pilot Tim D'Oyly at my side in the chamber to watch over the proceedings.
Last gasp
The problem is that there's less oxygen at higher altitudes (and less nitrogen and less of everything else). At 5,500 metres,
there is just half as much as at sea level. As a result, passenger planes are kept pressurised - but only to an equivalent
altitude of around 2,000 metres. Building a plane that could maintain full, sea-level pressure inside with drastically decreased
pressure outside at altitude would make them bulkier and more expensive.
Which means that if you've flown by plane, you'll have experienced the same symptoms I did: ears popping and the need
to clear them (that sort of yawning that one does to equalise the pressure across both sides of the eardrum, I learned, is
called the Frenzel manoeuvre). But as the air was sucked noisily out of the chamber and we quickly ascended to an
equivalent altitude of 7,600 metres (25,000 feet), I encountered first-hand experience of the ideal gas law that relates
temperature, pressure, and volume: it got cold.
Once we reached cruising altitude, I dropped the mask and got immediately to work on a number of tasks as my blood
used up the oxygen floating around in my blood and the tiny amount in the air. My time without the mask on was called
out in 30-second, and then later, 15-second intervals. I wrote down my address, tried a spot-the-difference exercise,
and was asked to remember a four-digit number.
When I started hyperventilating, my body's attempt to take in more air, I didn't even notice. Apparently I had taken on
a sickly grey colour, as had my fingernail beds, and my blood oxygen level plummeted from 99% before the exercise
to just 61%. I, however, felt like I was doing pretty well. The worst I felt was a bit of a warm flush, as if much of me
was blushing. Near the four-minute mark, I found myself literally trying to put a square peg in a round hole; this child's
toy is a popular test of cognition in hypoxic scenarios such as this.
The result? My handwriting went way downhill, I didn't spot the differences very well, and only remembered two of the four
digits when I was asked later. When I put the mask back on and got my first blast of blessed sea-level air, I had the worst
case of seeing stars I've ever experienced.
I think it safe to say that until I've had much more training, no one should put me in the cockpit of a fighter plane.
But I'll keep at it."
Altitude and that woozy feeling
"I'm in a simulated altitude chamber under the watchful eye of Des Connolly of QinetiQ's Human Performance division,
and they're about to suck most of the air out.
It's all perfectly safe - for much of my simulated journey into the skies I'll be wearing a mask that provides air, much like
the one fighter pilots wear. But for four minutes, I'll drop that mask and see how it feels to breathe the thin air at
7,600 metres (25,000 feet).
QinetiQ carries out such tests on fighter pilots to instruct them on the effects of hypoxia, or oxygen starvation. They also
use the chamber to test life-support systems for high-flying jets such as the Typhoon, systems which are designed to
whip into action in the event of sudden depressurisation.
The symptoms are mild, and they rob the mind of the ability to reason, so if it sneaks up on you, hypoxia will have you
unconscious and then dead before you notice a thing. At the altitudes that a Typhoon can fly, that time could be as little
as five seconds. Luckily, I've got physiologist and pilot Tim D'Oyly at my side in the chamber to watch over the proceedings.
Last gasp
The problem is that there's less oxygen at higher altitudes (and less nitrogen and less of everything else). At 5,500 metres,
there is just half as much as at sea level. As a result, passenger planes are kept pressurised - but only to an equivalent
altitude of around 2,000 metres. Building a plane that could maintain full, sea-level pressure inside with drastically decreased
pressure outside at altitude would make them bulkier and more expensive.
Which means that if you've flown by plane, you'll have experienced the same symptoms I did: ears popping and the need
to clear them (that sort of yawning that one does to equalise the pressure across both sides of the eardrum, I learned, is
called the Frenzel manoeuvre). But as the air was sucked noisily out of the chamber and we quickly ascended to an
equivalent altitude of 7,600 metres (25,000 feet), I encountered first-hand experience of the ideal gas law that relates
temperature, pressure, and volume: it got cold.
Once we reached cruising altitude, I dropped the mask and got immediately to work on a number of tasks as my blood
used up the oxygen floating around in my blood and the tiny amount in the air. My time without the mask on was called
out in 30-second, and then later, 15-second intervals. I wrote down my address, tried a spot-the-difference exercise,
and was asked to remember a four-digit number.
When I started hyperventilating, my body's attempt to take in more air, I didn't even notice. Apparently I had taken on
a sickly grey colour, as had my fingernail beds, and my blood oxygen level plummeted from 99% before the exercise
to just 61%. I, however, felt like I was doing pretty well. The worst I felt was a bit of a warm flush, as if much of me
was blushing. Near the four-minute mark, I found myself literally trying to put a square peg in a round hole; this child's
toy is a popular test of cognition in hypoxic scenarios such as this.
The result? My handwriting went way downhill, I didn't spot the differences very well, and only remembered two of the four
digits when I was asked later. When I put the mask back on and got my first blast of blessed sea-level air, I had the worst
case of seeing stars I've ever experienced.
I think it safe to say that until I've had much more training, no one should put me in the cockpit of a fighter plane.
But I'll keep at it."
