On Jul 27, 9:34Â pm, Stealth Pilot
aeroplanes.com.au>
wrote:> On Sun, 27 Jul 2008 08:33:06 GMT, Coop
chariotnose.netwheel.au>
> wrote:
>
>
>
>
>>>On Sun, 27 Jul 2008 11:44:58 +1000, "RMK"
bigpond.com>
>>wrote:>
>>>> one for the boffins and arm chair boffins on  here
>
>>>> Would  the damage potential  have been  greater/ the same/or less  to
>>>> an aircraft in similar circumstances at a higher altitude ? To the
>>>> recent QF incident
>
>>>> for discussion
>
> lets un mung those comments...
>
>>>The aircraft is pressurized to it's maximum pressure differential as it
>>>climbs (approx 8.9psi).
>
> wrong.
> what is correct is that  the aircraft is pressurised to a constant
> 8,250ft apparent cabin altitude as it rises past that altitude.
>
>
>
>>>So it's the same regardless of whether you are at 29000'or 45000'.
>
> entirely misleading. apparent cabin altitude is maintained to the same
> value. the pressure differentials needed to create the same internal
> pressure vary with increasing altitude.
>
>>>The only 'danger' is that the higher you are, the longer it takes to get
>>>down to
>>>a safe level if you lose cabin pressure.
>
> there are a few other dangers but it is probably good that you are
> blissfully unaware of them. (do you shivver?)
>
>
>
>>Yep, and the time to unconsciousness is shorter the higher you are
>>when the depressurisation occurs.
>
>>Coop
>
> it is good that the average pax is unaware of how short a period that
> is.
> Stealth Pilot- Hide quoted text -
>
link below is a slightly more extensive study of actual pressure in a
747-400 cabin over 3 airlines and 45 flights. Standard is 750HPa min
which is 8000ft. ( The 787 Dreamliner will have a 6000 ft max). The
link only has the abstract and it clearly states that the pressure
dropped 8Hpa per 1000 ft between 34000 and 40000 ft. reaching a
minimum of 792 HPa at 40000ft. It is not clear what was happening
below 34000ft.
http://www.find-health-articles.com/rec_pub_17587417-directly-measured-cabin-pressure...
