Khao Yai, Thailand: United Arab Airlines, Flight 869, registration SU-AMW, was an international passenger jet scheduled to fly from Hong Kong to Cairo with a stopover in Bangkok. The De Havilland DH-106 Comet had a very uneventful flight from takeoff, even though the plane was an older plane, it seemed like a normal flight.
Air traffic control in Thailand recorded no problems with the flight as the plane began its approach to the airport in Bangkok, before the plane vanished from radar. Using the distance from ground-based radar, rescue teams combed the Khao Yai mountain, some 59 miles northeast of the airport. No survivors were found, meaning that all 18 passengers and 8 crew aboard, died in the crash.
It is important to remember that at the time, only primary radar was in use in airports so things like the altitude of the plane at the crash were not known, but by examining the crash site, investigators determined that the plane had hit the mountain while cruising at near the same altitude. Without a FDR, investigators blamed the crash on the pilots calculations which “resulted in grave errors of time and distance in his computations”.