people thinking they only have 12 minutes to reach 10 000 feet in an emergency descent
Hmmm. I have a bit of an issue with this one.
Are you suggesting a liesurely descent at normal profile after a decompression? If so I hope I don't fly with your airline.
My reading of emergency descent checklists from various manufacturers leaves me in no doubt that if an emergency descent is required, then it is an urgent response, not at your convenience. It is probably also the reason why, on most aircraft, an emergency descent is a recall item (no time to pull out the QRH).
It might also explain why manufacturers specify that an emergency descent be carried out at Vmo. Certainly in cases of suspected aircraft damage a lesser
speed is suggested, however in such cases additional drag such as speedbrakes or landing gear are recommended to achieve the
descent rate required to reach a safe altitude in minimum time.
It was in fact originally a certification requirement that a manufacturer had to demonstrate the ability to complete an emergency descent from highest certified altitude to FL140
within 4 minutes.
Yes, most oxygen generators will provide 12 minutes supply to the passenger, however that does not give one the option of conducting an emergency descent at normal profile.
Where did you get the idea (if I am understanding your post correctly) that an emergency descent could take as long as, or longer than, 12 minutes?