When cabin is depressurized due to some or the other reason then we usually have oxygen generators in airplane and they last for 12 minutes. It is very shot in usual terms but it is enough to descend a plane instead can we use bleed air so that it is long lasting?
Some expected counter questions and answers:
Q. What you will do for old people and small children?
A. For people aged above 60 and below 15 have to use oxygen generators however they are very less people in number as seen from normal aviation photos?
Q. What if they have problems like hypoxia?
A. Always while taking ticket they ask that do you have such kind of things and they will be treated as above category?
Q. If it fails how can we do it ?
A. What you will do if passenger oxygen generator is failed?? That is my counter question however I am not telling to remove that oxygen generators fully but decrease capacity and decrease costs (note that same mask has both bleed air and oxygen from oxygen generator and this lining is light and cheap you can save more lives)?
Q. This will reduce safety
A. No never. Only it only decreases a bit of cost and it even can last longer and save lives more it is more safer reason: old people and children use only oxygen from generator and others use only bleed air
Q. If the air quality is bad?
A. The people use both oxygen generators and this bleed air and we can monitor air quality it is very very light and very very cheap like it is not even 10% cost of normal economy class ticket it is just bad to ask this. Even you can install multiple of them to monitor more clearly and and that will not cost much
Q. What if bleed air system fails?
A. My counter question what if the oxygen generator fails and what if normal bleed air system fails? It is like breaking the whole aircraft into 4 pieces in air. Of course there is oxygen cylinders in normal system if they don't descend it will become like Helios Airways flight 522