Why don't airlines have parachutes for passengers?

为什么民航上不给乘客配备降落伞？

原文地址：https://www.quora.com/Why-dont-airlines-have-parachutes-for-passengers

Andrew Hennigan:

There are four reasons why you don't find a parachute under your seat on commercial airlines.
基于以下几个原因，所以你坐商业航班的时候才不会在座位下面找到降落伞。

1. Parachutes are bulky, heavy and expensive. They would not even fit under your seat, they would occupy a lot of space and add a lot of weight. They would also need regular inspection and repacking. To provide several hundred per airplane would add significantly to costs, making flying much more expensive.
   降落伞笨重而且昂贵。那些降落伞甚至不能塞在你的座位那里，也就是说会占用大量的空间和额外的重量。同时还需要定期的检查和重新打包。在每个航班上增加几百个降落伞会显著增加飞行成本。

2. Passengers are not trained to use them. Without a minimum of training most people would not even be able to strap the parachute on correctly, never mind open it and land safely. Even on the ground and with plenty of time this is not easy. In the confined space of an airliner and in a high-stress situation it would be even more difficult.
   乘客没有受过适当训练。在没有基本训练的情况下乘客不懂如何打包降落伞，更不用提什么打开和安全降落了。即使是在地面上，花上大把的时间这也不是什么容易事儿。在客机上空间有限同时人员高度紧张，事情只会更加复杂。

3. There isn't a convenient way to jump out of typical airliners. You would need to redesign aircraft with a special jumping exit. Just jumping out of normal side-facing airplane doors or emergency hatches you would probably hit the wing or the tail. You would need to install a ramp on the rear of the cabin.
   离开飞机没有什么方便的方法。为了增加一个跳伞口就需要重新设计飞机。通过常规的飞机侧门或者紧急舱门跳伞可能会让你撞到机翼或者机尾。这样你就得给给你在背部装个斜板。

4. There are very few situations where it would save anybody. You would have to be in a situation, in daylight, over land where there is no hope of a landing but plenty of time to get everyone out. I can only think of a single case in the entire history of civil aviation where it could have been useful -- The United Flight 232 case (Wikipedia United Airlines Flight 232) -- but then only if the aircraft had been redesigned with a rear exit. Even in that case jumping was as risky as staying aboard.
   这种拯救乘客方式限制太多。这样的条件包括场景，在白天，下面也不是陆地自然也就无法降落，但有充足的时间让每个乘客逃生。在历史上这么多的空中险情中，我只能想出一个案例来运用降落伞这种逃生方式，那就是The United Flight 232 case (Wikipedia United Airlines Flight 232)，但如果飞机通过重新设计然后只能加了一个背部出口，即使是在这种情形下跳伞也和留在飞机里面一样危险。