Cathay Pacific Flight 700Z was a flight from Singapore to Hong Kong operated by Cathay Pacific using a Convair CV-880 aircraft that crashed 30 miles (48 km) southeast of Pleiku, then in South Vietnam, on the afternoon of 15 June 1972, killing all 81 passengers and crew on board.
It remains the deadliest aviation incident involving a Convair CV-880. An investigation was carried out by officials from Great Britain and Cathay Pacific, but efforts to retrieve wreckage and study the crash site were hampered by ongoing fighting in the region due to the Vietnam War.
An inquiry later determined the crash to have been caused by an explosive device, likely located within the passenger cabin. A Thai national was arrested as a suspect in the bombing but later acquitted at trial. Journalist John McBeth, who had worked for the Bangkok Post, described said trial as "Thailand's version of the O.J. Simpson trial."
It was the deadliest incident to occur on a Cathay Pacific aircraft, and at the time it occurred, it was the deadliest civilian aviation accident in South Vietnam.
Aircraft and crew
Flight 700Z was flown using a Convair CV-880 which had been manufactured in 1961 and bore the registration VR-HFZ. The Captain of the flight was 43-year-old Australian national Henry Neil Morison (who had a total of 14,343 flight hours, including 5,261 hours logged on the CV-880), 38-year-old First Officer Lachlan Campbell Arbuthnot Mackenzie (7,649 flight hours, with 2,867 hours on the CV-880), 42-year-old second First Officer Leslie Albert Boyer (5,783 flight hours, with 1,529 hours on the CV-880), and 36-year-old Flight Engineer James Kenneth "Ken" Hickey (4,246 flight hours, with 2,595 on the CV-880). There were six cabin crew from Hong Kong led by two pursers, William Yuen Hok-man and Dicky Kong Kar-wah .
Morison and Hickey were Australian, and based in Hong Kong, whilst Mackenzie and Boyer were British. Morison previously was in the Hong Kong Auxiliary Air Force, where he befriended Adrian Swire. Hickey had previously survived Cathay Pacific Airways Flight 033, an accident where a Convair 880 fell into Kowloon Bay.
Of the pursers, one was of British nationality and the other was of a Chinese nationality. Of the four regular flight attendants, two were of a Chinese nationality, one was of Singaporean nationality, and one was of British nationality. Gavin Young, author of Beyond Lion Rock: The Story of Cathay Pacific Airways, identified all of the cabin crew as "Hong Kong Chinese".
Passengers
36 of the passengers boarded in Bangkok. The remainder of the passengers on the sector that was bombed had boarded in Singapore.
The nationalities with the largest numbers of passengers were Japan, Thailand, and the United States.
A June 1972 article in The Age stated that there were 17 passengers from Japan, 16 from the United States, 10 from Thailand, six from Hong Kong, three from Singapore, two each from Taiwan and the United Kingdom, and one each from Bangladesh, France, and Ireland.
The Japanese passengers included 12 members of a tour group from Gunma Prefecture. About 150 relatives and friends, including coworkers and acquaintances, of the Japanese deceased traveled to Saigon and met with Cathay Pacific employees. Young stated that members of the Japanese groups in Saigon were "particularly vociferous", "agitated", and had given "impossible demands" to Cathay Pacific employees.
According to a June 1972 report from the Associated Press, 11 Americans boarded the flight in Singapore and were bound for Hong Kong. Additionally, the report stated, six Americans boarded in Bangkok. Therefore, that count stated there were a total of 17 Americans on the sector when the flight was bombed. The CEO and chairperson of the board of B.C. Ziegler, his wife, four of their children, and a family friend, all from West Bend, Wisconsin, United States, were among the deceased who boarded in Singapore. Among those who boarded in Bangkok were a member of the board of trustees of Indiana University and his wife.
There were seven members of one Filipino family on board.
Three Hong Kong residents boarded in Singapore.
Two passengers from the United Kingdom and one from Ireland who were bound for Hong Kong boarded in Singapore. The Irish passenger, a priest, trained Cathay Pacific flight attendants in their speech.
An article in the The Sydney Morning Herald stated that, whilst there were Australian crew members, no Australian passengers were recorded. Some other articles stated that one passenger was Australian.
Incident
Initial disappearance
Flight 700Z originated from Singapore with a scheduled stopover at Bangkok's Don Mueang International Airport, with the final destination being Hong Kong's Kai Tak Airport. The first leg of the flight proceeded without incident before the aircraft took off from Bangkok at midday with 71 passengers and ten crew members on board. The crew made regular radio contact for the initial leg of the flight.
At 05:42 GMT (12:42 local time), the flight made contact with Saigon ATC. At 05:44, the crew made a routine transmission updating the progress of their route, adding that they would expect to reach their next waypoint by 06:06 GMT. This was the last transmission received from the flight. After Saigon lost contact with the aircraft, they made an appeal for information to both Hong Kong and Taipei ATC which produced negative results. Saigon then initiated an investigation as to the aircraft's whereabouts. Initial reports speculated that the flight may have collided with an American military plane with Reuters and Agence France-Presse claiming Flight 700Z to have been involved in a mid-air collision. However, no reports emerged of any other aircraft missing in the area.
The wreckage was near the town of Cheo Reo (now called Ayun Pa). The crash location was about 30 miles (48 km) southeast of Pleiku, and about 200 miles (320 km) north of Saigon. It was located in what was Phú Bổn province. As of 2026 that area is in Gia Lai province in the Socialist Republic of Viet Nam (SRV).
Staff from the embassies of Japan, the Philippines, Taiwan, and the United States went to the wreckage location to help the identification process for the deceased.
Investigation
The wreckage was located by a United States Army helicopter in "lightly wooded" terrain on a remote hilltop near Pleiku, still burning, not long after Saigon ATC lost contact. Although two bodies were retrieved almost immediately, the presence of hostile Vietcong forces nearby made it very difficult to examine the wreckage in depth. South Vietnamese soldiers were drafted in to search for the wreckage and secure the crash site. It was reported that before the area was secured, local villagers and Viet Cong had gone through the wreckage looking for valuables. The South Vietnamese Civil Aviation Department, the Thai government, and Cathay Pacific Airways each had their own investigations. Two British men, Vernon Clancy and Eric Newton, went to the location to get information about the crash. Newton was the primary person investigating aviation accidents at the Civil Aviation Authority, while Clancy used to be a part of the Royal Armament Research and Development Establishment.
The spread of debris suggested that the airplane had broken into three large sections, with the breakpoints almost exactly along the front and rear of the wingbox, prior to hitting the ground, and the relative closeness of these sections suggested that this breakup had occurred at a low altitude. Other debris, including two engines and the horizontal stabilizer, could be seen further away from helicopters, but could not be reached on foot due to war activity. The rear section of the aircraft was later found impaled on a tree with the bodies of thirteen passengers and two cabin crew members still inside while the middle section was found to have exploded on impact with the ground. The aircraft's flight data recorder was recovered and read; it showed that the airplane was flying on course at 29,000 feet (8,800 m) at a speed of 310 knots (570 km/h) until 05:59 GMT (12:59 local time), at which point the recorded data became nonsensical for 30 seconds before stopping entirely. The aircraft was not equipped with a cockpit voice recorder. The detonation occurred after 64 minutes and 2 seconds in the air.
Upon examining the available debris, it soon became clear that the aircraft had suffered some sort of structural problem and loss of control at cruising altitude, and that the low-altitude breakup was caused by the overstressing of the airplane during an uncontrolled descent. Debris from the centre fuselage and right wing root showed signs of explosive "splash", and the number 3 fuel tank showed signs that it had ruptured prior to the low-altitude breakup inferred from the wreckage distribution. The vertical stabilizer showed signs that it had been struck by "at least one body and possibly some seats", and the horizontal stabilizer also showed signs of being damaged by debris in the air. Many bodies were not recovered, possibly because they had been ejected very early in this sequence. An investigator working at the crash site summarised that the plane suffered an explosive decompression around 1pm local time. According to Young, the cabin crew were found wearing serving jackets and aprons, and so "One can assume" that the crew were serving lunch at the time of the in-flight breakup. The passengers standing in the aisle or queuing for the lavatory and cabin crew members overseeing the meal service were sucked out of the aircraft as it disintegrated.
Without being able to better examine the wreckage, and lacking valid flight data from the final moments of the flight, it is not known what exactly happened after 05:59 GMT. Investigators concluded that apparently some sort of explosive device, likely located within the passenger cabin near the right wingbox, detonated at that time, causing unknown but catastrophic damage to the aircraft, including but not limited to the damage found on the horizontal and vertical stabilizer. The aircraft likely descended rapidly in an "erratic" manner. At an undetermined point in this descent, the horizontal stabilizer separated from the airplane entirely, and eventually the fuselage broke into the three sections initially found by searchers.
According to McBeth, experts had theorised that the person bombing the aircraft intended for it to fall into the ocean, which would make extracting information from the debris more difficult. McBeth said, "The Cathay Pacific bomber erred in his timing." The aircraft would have begun flying over water six minutes after the time the bomb detonated.
Suspect and his behaviour
Somchai Chaiyasut was a lieutenant in the Thai police organisation. He was based at the airport and a part of the police aviation division. He attended Adamson University where he married a Filipina woman and fellow student, Alice Villiagus; they divorced later due to Somchai's parents disliking her. Somchai decided that their daughter, Sonthaya Chaiyasut, should live in Thailand, and Villaigus accepted this arrangement.
Sonthaya, seven years old, and Somchai's girlfriend, 20-year-old Somwang Prompim, were passengers on CX700Z. Somwang worked at a coffee shop, and her family, low income and working in agriculture, came from Northeast Thailand. Somchai said Somwang was from a prominent family, and he said on insurance policies that she was his wife, when they had not formally married. To airport staff, Somwang seemed relatively uneducated and lacked English fluency.
Sonthaya's corpse was not found, but Somwang's corpse had mutilation that meant that a bomb had likely exploded in her location. Her legs past the knee were not present, and of the bodies, hers had the highest number of fragments. Her face and teeth were missing, frustrating identification. According to Cathay Pacific employees at Bangkok airport, Somwang only took hand baggage, a black cosmetic case, and did not check any luggage. Somchai had taken out travel accident insurance policies from American International Assurance and New Zealand Insurance, totaling 3,100,000 Thai baht, about $150,000 U.S. dollars. The former company insured Somwang for 1 million baht ($50,000 USD), and the latter insured Sonthaya for 100,000 baht and Somwang for 2 million baht.