On 22 August 1999, a Boeing MD11 being operated by China Airlines on a scheduled passenger flight from Taipei to Hong Kong carried out a normal ILS approach to Runway 25 Left in a strong crosswind and some turbulence but the night landing on a wet runway surface in normal visibility was very hard after a high sink rate in the flare was not arrested. The right main landing gear collapsed, the right wing separated from the fuselage and the aircraft caught fire and became inverted and reversed ending up on the grass to the right of the runway. Rapid attendance by the RFFS facilitated the escape of most of the 315 occupants but there were 3 deaths and 50 serious injuries as well as 153 minor injuries. The aircraft was destroyed.
An Investigation was carried out by the Accident Investigation Division of the Hong Kong Civil Aviation Department with assistance from the UK AAIB and the National Transportation Safety Board (USA) (NTSB). It found that after becoming visual with the runway at approximately 700 ft, the aircraft commander, who was a Training Captain and acting as PF for the sector disconnected the Autopilot but left the Auto Throttle system engaged. The aircraft had continued to track the extended runway centreline, but descended and then stabilized at about half scale below the ILS GS. Although an attempt was made to flare the aircraft, no thrust was added and the action taken was ineffective and led to an extremely hard impact with the runway in a slightly right wing-down attitude at an estimated landing weight just below MLW. It was found that the rate of the descent during the last 300 feet of the approach had averaged approximately 1000 fpm and that this was the rate of descent at touchdown. The approach and landing were characterised by a strong crosswind from the right at or marginally in excess of the prescribed wet runway landing limit. The aircraft commander’s crosswind approach technique was found to have been in accordance with Operator SOPs and therefore not considered to be contributory to the accident outcome.
The Investigation noted that although the “late and sporadic crew briefings for the approach, including reference to the wrong runway, are not considered to have contributed directly to the accident, they do have human factors aspects”
It also found that:
- Neither pilot perceived the increasing rate of descent and decreasing indicated airspeed as the aircraft approached the landing flare.”
- The commander’s attempt to flare the aircraft by initiating a small increase in pitch attitude, as prescribed in the MD11 Standard Operation procedure (SOP) Manual was in the circumstances ineffective.”
- The aircraft touched down …at a rate of descent calculated as approximately 18 feet per second, well beyond the design structural limit of 12 feet per second.
The Investigation concluded that “the cause of the accident was the commander’s inability to arrest the high rate of descent existing at 50 ft RA.” and that “’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 kts loss in indicated airspeed just prior to touchdown.”
It was also considered that 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.
Safety Recommendations were made as a result of the Investigation as follows:
- China Airlines should remind its MD11 pilots of the need for an early and complete approach briefing
- China Airlines should review the content of its CRM training course to ensure that contributions made by the monitoring pilot, in operational situations, are both accurate and appropriate.
- China Airlines should review its MD11 training syllabuses to ensure the crew monitor the automated systems on the flight deck, so as to be ready to intervene, or override manually, whenever necessary.
- China Airlines should consider the introduction of a ‘Flight Instructor Guide’ of a type used by other MD11 operators and which includes advice to training staff on techniques to be followed during crosswind landings.
- China Airlines should, in association with the Boeing Company, amend the recommended landing procedures in the MD11 SOP to include procedures for approaches and landings in more demanding weather conditions.
- China Airlines should ensure that crosswind landing limitations noted in its publications are consistent throughout.
- China Airlines should re-emphasise to flight crews the need on instrument approaches, to continue to monitor the flight instruments in the final stages of the approach as prescribed in the China Airlines Flight Operations Manual (FOM).
- The Boeing Company and the equipment vendor should conduct a study to examine methods for preventing the loss of QAR data in the event the equipment is switched off in a non standard way such as by an interruption to the power supply.
- The Hong Kong CAD should give consideration to the installation of equipment, such as video recorders, to monitor the touch down zones of Runways 25 R/L and 07 R/L.
- Airport Operator HKO should provide information regarding the character of airflow in the vicinity of the TDZ of RW 25L and RW 25R in conditions of severe tropical storms and, in particular, when the wind directions are between northwest, through north, to south with the purpose of providing the CAD with further advisory meteorological information to be included in the Hong Kong AIP.
The Final Report of the Investigation was published in December 2004 ad may be seen in full at SKYbrary bookshelf: Report of the Board of Review on the Accident to Boeing MD-11 B-150 at Hong Kong International Airport on 22nd August 1999