Eastern Airlines Flight 401 crashed in the Everglades on Dec 29, 1972 and 101 people perished. Capt Robert Loft survived the impact but died after he was removed from the aircraft. Officer Donald Repo died 1 day later. Eastern Airlines
salvaged much of the L-1011 Whisperliner aircraft and distributed the parts among other aircraft in its fleet.
Not long after the redistribution the sightings began. People reported seeing the ghosts of Loft and Repo in the planes that had received spare parts from Flight 401. Repo's ghost appeared in the cockpit and the galley and seemed to be very concerned about safety. He pointed out fire hazards and safety concerns to whoever was present to listen. Loft's ghost was also seen sitting in 1st class. A stewardess thought he was a stowaway and reported the situation to the captain. Captain recognized the apparition immediately and then Loft vanished before their eyes.
here were numerous reports like these from the dozens of planes containing 401 parts.
Eastern Airlines rejected the claims and referred employees to counselors. When the stories didn't stop they threatened to fire employees who told ghost stories about Flight 401. In the end the airlines removed the salvage parts. No more sightings were reported. There's a book about this called "The Ghost Flight 401" by John Fuller.