Helios Airways Flight 522
The mystery behind this flight is the deadliest aviation accident in the history of Greece. Helios Flight 522 was scheduled to fly from Larnaca, Cyprus to Athens, Greece. It crashed, killing all 121 passengers and crew members on board. An investigation revealed there was a gradual loss of cabin pressure, but further information remains unknown.
Flying Tiger Line Flight 739
Back in the ’60s, a Lockheed L-1049 Super Constellation propliner carrying 93 US soldiers and 3 South Vietnamese disappeared in clear weather on its way to Clark Air Base in the Philippines. There was an 8-day intensive search of more than 2000,000 miles. No body parts were ever found.