Descripción:China Airlines flight 642 departed Bangkok for a flight to Taipei via Hong Kong. Weather in the Hong Kong area was very poor with a severe tropical storm ('Sam') 50 km NE of the airport and gale force winds and thunderstorms. Extra fuel was carried, because the crew intended to continue to Taipei, depending on weather at Hong Kong on arrival. Before the arrival of flight 642 four flights carried out missed approaches, five planes diverted and 12 planes landed successfully.
|Fecha:||domingo 22 agosto 1999|
McDonnell Douglas MD-11
|Numéro de série:|| 48468/518|
|Año de Construcción:|| 1992|
|Horas Totales de la Célula:||30721|
|Motores:|| 3 Pratt & Whitney PW4460|
|Tripulación:||Fatalidades: 0 / Ocupantes: 15|
|Pasajeros:||Fatalidades: 3 / Ocupantes: 300|
|Total:||Fatalidades: 3 / Ocupantes: 315 |
|Daños en la Aeronave:|| Anulado|
|Consecuencias:|| Written off (damaged beyond repair)|
|Ubicación:||Hong Kong-Chek Lap Kok International Airport (HKG) ( Hong Kong)
|Fase:|| Aterrizaje (LDG)|
|Naturaleza:||Vuelo Internacional Programado|
|Aeropuerto de Salida:||Bangkok-Don Muang International Airport (BKK/VTBD), Tailandia|
|Aeropuerto de Llegada:||Hong Kong-Chek Lap Kok International Airport (HKG/VHHH), Hong Kong|
|Número de Vuelo:|| 642|
Weather information obtained by the crew at 18:06 reported a 300deg wind at 35 knots and an RVR of 650 m in heavy rain. The flight crew then prepared for a runway 25L ILS approach. Landing reference speed was calculated to be 152 knots and the captain (pilot-in-command) would fly the approach at 170 knots and would continue to land depending on a wind check on finals.
At 18:41, while flying the runway 25L ILS approach, weather was reported to the crew being 1600 m visibility in the touchdown zone, wind 320deg/25 knots gusting to 33 knots. The aircraft was then cleared to land. At an altitude of 700 feet prior to touchdown a further wind check was passed to the crew: 320deg/28 knots gusting to 36 knots. Maximum crosswind component limit for the aircraft was 24 knots. The pilot-in-command continued with the approach, disconnected the autopilot but left auto throttle engaged. The MD-11, with a weight very close to the maximum landing weight permitted, stabilized slightly low on the glide slope. At 50 feet above the runway, upon power reduction to flight idle, the airspeed decreased from 170 to 152 knots. An attempt was made to flare in a slightly right wing down (less than 4 deg) attitude. The aircraft landed hard on its right main gear and the no. 3 engine touched the runway. The right main gear separated and the right wing separated. The MD-11 then rolled inverted as it skidded off the runway in flames. It came to rest on a grass area next to the runway, 1100 m from the runway threshold. The right wing was found on a taxiway 90 m from the nose of the plane.
The crash sequence in this case bears similarities to a Fedex MD-11 which also flipped upside down on landing at Newark.
Probable Cause:CAUSAL FACTORS:
"The cause of the accident was the commander’s inability to arrest the high rate of descent existing at 50 ft RA.
Probable contributory causes to the high rate of descent were:
(i) The commander’s failure to appreciate the combination of a reducing airspeed, increasing rate of descent, and with the thrust decreasing to flight idle.
(ii) The commander’s failure to apply power to counteract the high rate of descent prior to touchdown.
(iii) Probable variations in wind direction and speed below 50 ft RA may have resulted in a momentary loss of headwind component and, in combination with the early retardation of the thrust levers, and at a weight only just below the maximum landing weight, led to a 20 kt loss in indicated airspeed just prior to touchdown.
A possible contributory cause may have been a reduction in peripheral vision as the aircraft entered the area of the landing flare, resulting in the commander not appreciating the high rate of descent prior to touchdown."
China Airlines and the plane's co-pilot applied for a review of the findings and conclusions of the accident report. In September, 2002, the Chief Executive appointed an independent Board of Review made up of a Principal Magistrate and two overseas expert assessors. Their report completed in December, 2004.
Regarding the causal factors, the Board of Review rejected the part of the causal factor relating to the maximum landing weight in para. (iii) being a possible significant contributing cause to the high rate of descent: "In relation to para. (iii), we are of the view that the reference to aircraft weight is possibly misleading as any increase in drag resulting from the aircraft weight would have been minimal and a heavier aircraft would have more inertia and possibly greater stability in these particular circumstances. Furthermore, the extra fuel carried would have allowed for a wider range of aircraft diversion options, thereby relieving some of the pressures on the crew to avoid a go-around."
Official accident investigation report
Subsiguiente / acciones de seguridad
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not
display the exact flight path.
Distance from Bangkok-Don Muang International Airport to Hong Kong-Chek Lap Kok International Airport as the crow flies is 1677 km (1048 miles).