[PATCH 2/2] Add initial rudimentary no-fly time calculation

[Linus Torvalds]

On Fri, Feb 8, 2013 at 10:34 PM, Linus Torvalds
<torvalds at linux-foundation.org> wrote:
> On Fri, Feb 8, 2013 at 9:51 PM, Robert C. Helling <helling at lmu.de> wrote:
>>
>> Not neccessarily. With the Buehlmann a and b factors (leave out gradient
>> factors for the moment) there is a tolerance for an over pressure (partial
>> pressure of inert gas can be higher than ambient pressure).
>
> Right. But the point is, there's a limit to how much that tolerance
> can be. Especially if we use gradient factors to make the tolerance
> calculations more conservative (which we'd absolutely do).
>
> And maybe catastrophic pressure loss could still be within that limit,

No it's not.

Some googling says that decompression sickness apparently occurs for
some people (without any diving!) at 23,000 ft. Thank the Gods for
military test-subjects who can be used as guinea pigs.

So you really cannot take catastrophic cabin pressure loss into
account, or you'd never fly at all, diving or not. At some point you
just have to accept that flying implies some risk. If the skin of your
airplane ruptures at 33000 feet, you are going to have some unhappy
passengers. Just hope to get the plane down quickly enough into that
big round hyperbaric (well, _relatively_ hyperbaric) chamber below you
to fix the bends.

The *good* news is that planes with serious problems tend to
automatically descend into that huge hyperbaric chamber, so the
situation fixes itself. The bad news is that they sometimes do so a
bit too quickly and abruptly, which causes its own set of problems
totally unrelated to the bends ;^)

Anyway, it looks like it would definitely not make sense to aim for a
*much* higher altitude than the 12000 ft range.

                      Linus

See for example http://www.ncbi.nlm.nih.gov/pubmed/12433227