What happened
Flight CX700Z was operating a scheduled international service from Singapore to Hong Kong, including a planned stopover in Bangkok. During the 55-minute layover in Bangkok, 68 passengers and their luggage were removed from the aircraft, while 35 new passengers and baggage were boarded along with 35,000 lbs of JP-1 fuel.
The Convair aircraft departed Bangkok at 0455 hours GMT, climbing to flight level 290 via airway Green 67. The flight initially maintained standard communication with Bangkok ACC before transitioning to Saigon ACC at 0542 hours. At 0553 hours, the crew reported their position over the "PE5" reporting point while maintaining FL290, estimating they would reach the "XVK" point by 0606 hours.
Following this transmission, the aircraft ceased all radio contact. After several unsuccessful attempts by Saigon ACC to reach the flight, and subsequent inquiries to Hong Kong and Taipei ACCs yielded no information, the distress phase was officially initiated at 0715 hours. At 0755 hours, the Tan Son Nhut RCC received reports that a Convair aircraft had crashed approximately 30 NM southeast of the Pleiku TACAN beacon.
Helicopter pilots arriving at the site while the wreckage was still on fire identified the registration as VR-HFZ. They recovered two bodies from the burning debris, but the aircraft was completely destroyed. There were 81 fatalities and no survivors from the accident.
Findings
The investigation determined that the aircraft suffered an in-flight breakup and subsequent fire caused by the detonation of a high explosive device inside the passenger cabin.