Read the full text and talk about the reasons why there are no parachutes on civil aviation planes.

There are two reasons: (1) The fighter pilot parachuted, actually the rocket engine behind the flight seat ignited, and the pilot was thrown out with the seat (note that it was a projectile). In this process, the pilot's spine has to bear a great overload (figuratively speaking, assuming that the pilot's upper body weighs 40 kilograms, the force on his spine is about 300 kilograms). Ordinary people's spine simply can't bear such an impact. (2) When parachuting, paratroopers use a special plane, which is slow and has a high tail, which can ensure that athletes will not touch the tail when jumping out of the plane or simply using the back door of the plane. This is not the case with civil aircraft. You can't imagine hundreds of people huddled in a cabin, each with an umbrella bag and in a hurry.

2. From the benefit cost of the whole society, it is not cost-effective.

Because the air crash is a small probability event after all, air transportation is generally safe. It's a bit like a car, in order to make it more

Yes, we can design the car so that the speed of the car does not exceed 20km/h, or we can make the car into a tank to ensure that it will not deform after the collision. If so, the car is safe, but the overall benefit will be reduced.