June 8, 1924... Climbing Mt Everest. Andrew Irvine and George Mallory disappeared.
December 17, 1967... Australia Prime Minister Harold Holt disappears at Cheviot Beach. Marjorie Gillespie, mistress was present.
June 6, 1989... Columbia Scientific Balloon Facility. NASA balloon. Altitude of 120,000 ft - 22 miles. Lost payload. High altitude lightning.