Corsetti also said that the DC-9 didn't have life raft capacity for all those aboard.

CNN: Previous jet ditchings yielded survival lessons

As it does, the plane's left engine hits a reef, Corsetti said, sending it into a cartwheel.

CNN: Previous jet ditchings yielded survival lessons

The A320 also is equipped with a ditching button, Corsetti said, which closes all valves below the waterline, enabling it to float more easily.

CNN: Previous jet ditchings yielded survival lessons

Sullenberger had other advantages, too, Corsetti said.

CNN: Previous jet ditchings yielded survival lessons