# Cathay Pacific Flight 700Z

Cathay Pacific Flight 700Z was a flight from Singapore to Hong Kong operated by Cathay Pacific using a Convair CV-880 aircraft that crashed in 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, Cathay Pacific's parent company the Swire Group and the Hong Kong Police 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.

## 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 Neil Morison (who had a total of 14,343 flights hours, including 5,261 hours logged on the CV-880), 38-year-old First Officer Lachlan Mackenzie (7,649 flights hours, with 2,867 hours on the CV-880), 42-year-old second First Officer Leslie Boyer (5,783 flight hours, with 1,529 hours on the CV-880), and 36-year-old Flight Engineer Ken Hickey (4,246 flight hours, with 2,595 on the CV-880). There were six cabin crew of Hong Kong nationals led by two pursers, William Yuen and Dicky Kong.

## 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 0542 hours GMT (1242 local time), the flight made contact with Saigon ACC. At 0544, the crew made a routine transmission updating the progress of their route, adding that they would expect to reach their next waypoint by 0606 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 ACC 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.

## 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 ACC 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 had gone through the wreckage looking for valuables. A team of investigators from Cathay Pacific's parent company the Swire Group and the UK Civil Aviation Authority were sent to examine the area. 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 0559 GMT (1259 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.
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 when lunch was being served and that 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 0559 GMT. Investigators concluded that what is apparent is that 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.

## Aftermath

Following a UK Civil Aviation Authority and Hong Kong police investigation, as well as six years of reporting by a Bangkok Post journalist, "a police officer whose fiancée and daughter were aboard was charged with the crime". Somchai Chaiyasut, who had taken out three travel insurance policies on his fiancée and daughter, was declared not guilty due to lack of evidence. He sued the insurance companies and received 5.5 million baht ($US 180,000). He died of cancer in 1985. It was reported that "airline staff and relatives [had considered] hiring a hitman to kill him".