Why commercial planes don't have parachute to save life of passengers in case of emergency?

Answer 1

One simple reason: practicability. First of all parachutes are expensive. And having 200 or more parachutes on a fleet of 150+ airplanes would blow airlines' budgets to pieces. Another reason: weight. The weight of all the parachutes would severly limit the capacity of an aircraft. And finally, parachutes are sometimes difficult to operate and would not work with children or people with special needs.

Also, many aircraft accidents happen either immediately after takeoff or just before landing, and there is no time to get all the passengers to put on parachutes (almost all of whom would never have had done so before), get them to the exits and get them out of the airplane, which would also need to be at a sufficient altitude for the parachutes to open safely (before the person wearing the parachute hits the ground). Another consideration is weight and balance. Having all the passengers run to the back of the airplane so they can jump out, when the airplane is already in trouble, may not be the best thing to do (can't jump from the front doors; too many things to hit (i.e., wings, tail, antennas, landing gear, flaps, etc.), and the possibility of ingestion into the engines!) The January 2008 accident involving a British Airways 777 at London-Heathrow is a perfect example of an incident where there was absolutely no time to respond. The flight crew didn't even have time for a 'Mayday' call on the radio, or to tell the passengers and cabin crew to brace for impact. Things can sometimes happen very, very quickly, and in this case the flight crew did an excellent job in getting the airplane on the ground in as few pieces as possible.