for long I had the cuorisity about not having a parachute in passanger planes. Today I read an article on it. The writer , having an experience of 33000 miles air travel, summarized some reasons :
In order to parachute from a commercial jet it would need to be
• in a stable altitude,
• at low air speed,
• and below about 12 000 ft.
but these does not happen in case of commercial flights. besides some other reasons :
There are several other reasons for not using parachutes in commercial jets,
• The door of a passenger plane cannot be opened in mid-flight. Even military parachutists wait till the plane gets stable to exit.
An opening in an aircraft destroys the whole fuselage.
• Each parachute may weigh 8–10 kgs and too expensive.
• A commercial jet which is cruising at 35,000 feet (almost three times higher than a typical jump) every passenger would need equipment like an oxygen tank, mask and regulator, flight suit, helmet and altimeter just to manage the thin air. Or they could just pass out from hypoxia and wake up later.
• passengers have no practice or training about how to use parachute usage.
• one can't think about the impact/injuries during landing after he jumps. It may be to an open ocean, jungle or desert.
and lastly a funny reason:
Tickets will become expensive and we know majority of the passengers choose only cheaper aircraft sometimes.