An investigation by the National Transportation Safety Board (NTSB) determined that multiple crew errors were the primary cause of the crash.

On the morning of September 11, 1974, while conducting an instrument approach in dense ground fog into Douglas Municipal Airport in Charlotte, the aircraft crashed at 7:34 am EDT more than three miles (5 km) short of Runway 36, killing 72 of the 82 on board.

It was later realized that this rule should also apply to takeoffs; for example, the lack of a sterile cockpit environment was a contributing factor to the crash of Air Florida Flight 90 on January 13, 1982.

[9][10] The NTSB also found that the crew was apparently trying to visually locate the airport while executing an instrument approach in the presence of low-lying fog.

[5] The NTSB released its final report on May 23, 1975,[5] concluding that the accident was caused by the flight crew's lack of altitude awareness and poor cockpit discipline.