In his book, Flight 232: A Story of Disaster and Survival, Laurence Gonzales tells the story of United Airlines Flight 232 that crashed in Iowa on July 19, 1989. In all, 184 of the 296 passengers and crew lived, but the losses could have been much worse if United Airlines hadn't learned some crucial lessons from an earlier tragedy.

That earlier crash occurred on December 28, 1978. United Flight 173 was flying from New York to Portland, Oregon when it went down in a wooded suburb six miles from the airport. The plane had a malfunction of the landing gear on approach, so the captain began circling the area to make sure that the gear was down. Preoccupied with his landing gear, Captain Malburn "Buddy" A. McBroom, 52, ignored the crew's warnings that fuel was low. When the engines began quitting, McBroom understood his mistake. The plane crashed, killing 10 passengers and seriously wounding 23.

Gonzales writes:

Those at United Airlines and the NTSB [National Transportation Safety Board] believed that the military backgrounds of most airline pilots at the time contributed to the crash. The captain of the ship was supreme, and the other members of the crew were expected to defer to him and keep their mouths shut. It was a military tradition going back hundreds of years. This crash had a direct bearing on the fate of United Flight 232, because after the crash of United Flight 173, the NTSB recommended retraining flight crews in what came to be known as cockpit (or crew) resource management (CRM). United Airlines pioneered the training, in which captains were taught to listen to their crews, and the members of their crews were taught to be assertive if they thought that a hazardous condition was developing.