ask26
…Concorde… in the event of rapid depressuriation at 60000ft, were all passengers and crew doomed?…
A near-instantaneous decompression at 60,000 ft would have been very serious.
Passengers exposed to atmospheric pressure
at that height for any appreciable length of time would have had only a few seconds of awareness followed by a merciful lapse into unconsciousness.
The sort of damage necessary to have caused this would have brought with it a whole host of other problems, and probably the aircraft would have ceased to be a viable flying machine - the early Comet accidents being a case in point.
However, in the overwhelming majority of decompressions, experienced over many years, on all aircraft types, the aircraft did not instantly depressurise to ambient atmospheric pressure, even if it may have felt like it to the occupants.
Whether due to pressurisation system failure, discharge valve failure, a small hull breach, a door or window blow-out, or just plain human error, the cabin took time to decompress, often a considerable amount of time.
It is this time, the time the cabin takes to climb which provides the flight crew with a safety margin, precious seconds in which to act to protect passengers and crew from extreme cabin altitudes.
… What procedures did Concorde have in place in the event of rapid depressuriation at 60000ft…
Just as on subsonic jets, the crew would have been:
- Protecting themselves….pressurised O2 masks.
- Analysing the situation….what warnings?, what cabin rate-of-climb?
- Rectifying if possible….re-instating packs, selecting alternate systems, closing errant valves manually.
- If control of the cabin had been irretrievably lost….initiating an emergency descent.
Starting from FL600, the initial rate of descent would have been around 12,000 - 15,000 fpm, reducing on passing through FL500 and increasing again on passing through FL400.
On Concorde, once below FL500 an emergency descent also became a deceleration manoeuvre, which brought with it the necessity to move fuel forward rapidly to keep the CG within limits as the aircraft Mach number decreased.
Various emergency descent profiles were tried during test flying. The one that was finally adopted for line operations gave an average rate of descent of around 7,000 fpm, and kept the CG within limits throughout.
…As the time to unconciousness at 35000ft is a matter of seconds - would it have been likely there could have ever been any survivors…
The cabin altitude on Concorde was typically around 5,000 ft in the cruise, and in common with most commercial aircraft, various flight deck warnings would occur as the cabin altitude rose through 10,000 ft, and again passing through 14,000 ft, to alert the crew to any problem, assuming their own eyes, ears, sinuses and lower intestines had not already done so!
There were also many protection devices fitted to Concorde to ensure that the cabin altitude never exceeded 14,000 ft, however, even had they all failed and the cabin had been climbing at 5,000 fpm, it would still have taken 36 seconds before the cabin altitude exceeded 8,000 ft.
It would have taken 108 seconds before it exceeded 14,000 ft and around 3 minutes for the cabin to exceed 20,000 ft, by which time the aircraft would have been well on its way down to safety in an emergency descent.
In most cases, the cabin altitude would never have got above 20,000 ft, and the overwhelming majority of these incidents, though alarming, would have been highly survivable for all occupants. The chances of passengers ever being exposed to atmospheric pressure at FL600 was an extremely remote possibility.
It never even came close to happening, during 27 years of commercial service.
…the only things I have found were that the windows were built smaller to avoid air escaping…
Correct. The windows on the production aircraft were smaller than on the original test aircraft for that reason.
…and that pilots and crew would have used pressure breathing…
Only the flight deck crew had pressure breathing masks.
Regards
Bellerophon