The crash changed aviation history. In civil aviation transport, any negligence, the cost is extremely painful. In this lesson, we are going to learn about four classic cases in the history of civil aviation in the world: cabin decompression, on-board fire, pilot incapacitation, and water landing. It is these flight accidents that enable human beings to make continuous progress in the exploration of aviation safety, which leads to today's more and more standardized technology and system guarantee, which protects the safety of every passenger's life. We still have the courage to go into the cabin and feel the speed and convenience provided by modern science and technology.