What is different when we fly at 10 km altitude?

An aircraft is a highly complex structure consisting of several tens of thousands of individual components, some of which are even in double or triple amounts. There is a good reason for this, because an aircraft needs to stay in the air for short or long distances, and it needs to take off and land safely;  but, it cannot stop at any time - as a car can - to have a  quick look where a problem may be,  if there is one. Moreover, first, one has to come down from a height of 10km to get on the ground - if there is such an opportunity.

At an altitude of 10,000 meters, almost everything is different. There is not enough air to breathe, it is also really cold (as low as minus 60°C) and the air pressure is so low a person would faint immediately. This is why the interior cabin is a so-called pressurized cabin; the air pressure is artificially generated and because there is almost none left on the outside, it is higher on the inside; also, the hull in which passengers and crew sit, must be reasonably stable in order to withstand the pressure difference. At the same time, its entire weight should be as light as possible. Sometimes a fully loaded aircraft (gross weight, kerosene, luggage and passengers) weighs between 50 to over 560 tons (Airbus A 380). Airplanes are a technical marvel.

By the way, it is the opposite on a submarine. The greater the depth, the heavier the pressure of the water masses from the outside. A submarine must therefore have a very thick (and at the same time heavy) hull.  

And this is what the bleed pipe looks like in reality. In a 2 1/2 minute video (by clicking on the picture) the British ex-pilot Tristan LORAINE, who like many others also became unfit to fly, explains how to drastically reduce the problem. This is done by installing a filter before the bleed air enters the aircraft interior.

So far, many, not all aircraft have so-called HEPA filters. But not at the air intake. These HEPA filters inside the aircraft recycle up to 50% of the used air in the cabin. In other words, some of the air inhaled by passengers is returned to the outside, while the other part is recycled through a filter of this type.

Before LORAINE explains the additional filter that should be installed, it shows a bleed air pipe:

In 2004, the British Civil Aviation Agency photographed what bleed air pipes look like when they are damaged by pollutants or dirt on the inside. The report can be downloaded at http://publicapps.caa.co.uk/docs/33/CAPAP2004_04.PDF. The two pictures can be found on page 46 (PDF count) and in chapter 2, page 14.

Figure 1 shows a new, 'unused' breathing-air pipe. Picture 2 an older one.

Perhaps breathing-air pipes should not look like a chimney pipe from the inside?

Whether carbon or labyrinth seal(s) and regardless of how they work or leak:

Up at 10km height in the (still) air, the air pressure is regulated to an altitude of about 2,400m, i.e. 500m lower than the mountain ‚Zugspitze’ in the Bavarian Alps. This means that the air pressure is only 75% of what you are used to on the ground. As a result, the oxygen content is also significantly lower,  to which human organisms react differently. You can read about it in the "Compendium of Aviation Medicine", on page "1-27". (not translated yet).

For example, foreign substances are metabolized differently. This means that the body tries to break down a substance which is not its own and which it does not recognise, or does not like very much, into other substances. At least those bodies that work.

This happens for each person in different ways - one faster, the other slower. With some substances this does not work at all, e.g. regarding deadly poisons, or other toxic substances.

In a completely different and compressed air environment as described above, medication  can also react differently. Sometimes not at all. Or just at a fraction.

For passengers, a flight is a temporary thing. Flights longer than 13 hours (e.g. Frankfurt - Buenos Aires) are rare. As a rule, they are significantly shorter.

It's different for the crew. For them the cabin or cockpit is their workplace. The toxic body load is thus potentially higher. Significantly higher. And that's potentially where the problems for crews begin.

When a so-called leakage occurs and contaminated air flows into the cabin and/or cockpit, it is called a "Fume Event". This does not always have to be associated with smoke and/or bad smell (fumes). It depends on the substances that get into it: burnt oil or its additives (such as TCP), hydraulic fluids, de-icing agents in winter (which are designed for a temperature of 80°C) and much more. So far, about 200 such chemical substances have been identified. Not much is yet known about them, never mind about the interactions between them.

We analyze why this is the case in: Who, how, what and why. If you don't do research, you stay stupid. - Casuistic in occupational medicine (to be translated).

The health consequences for those affected are summarized under the term "aerotoxic syndrome". The effects can occur very suddenly, but they can also occur only in the medium to long term. We document all this and how employers and occupational medicine deal with it in: The Aerotoxic Syndrome in Occupational Medicine (not yet translated).

How the statutory accident insurance, specifically how the responsible professional association deals with this problem in general, is described in: The Berufsgenossenschaft Verkehr. Or: Who isn’t ill, doesn’t create cost (not yet translated). Employees are insured by the employers' liability insurance association in the event of accidents at work or work-related illnesses.

We will demonstrate what this looks like with one specific case: a pilot who has become unfit to fly, respectively is unable to work as a result of a Fume Event He is now fighting for to get it recognised as an occupational disease. His financial existence will also depend on it: Once a pilot - never again a pilot (not yet translated).

If you want to know more about the problem of contaminated cabin air and why it took so long before you even came across it, you can find more in our Chronology of Contaminated Cabin Air: a health problem becomes certainty. 

All other texts displayed in the navigation bar on the right (smartphones: scroll down to the bottom!) concentrate on the question why the problem can no longer be ignored, but why nothing changes. This is where occupational medicine and statutory accident insurances come into play (more at www.ansTageslicht.de/Arbeitsmedizin - not translated yet).