Investigation Summary
The accident occurred during the first year of operation for the new Chek Lap Kok airport. Tropical Storm Sam was approximately 50 km northeast of the field, generating significant wind shear and turbulence. The crew had loaded extra fuel to allow for a diversion to Taipei if landing proved impossible, but they elected to attempt the approach to Runway 25L. At the time of the accident, the aircraft weighed approximately 443,000 lbs, which was below the Maximum Landing Weight (MLW) of 458,000 lbs, though high for the prevailing weather conditions. Flight data indicated that at approximately 50 feet above the runway, the autothrottle performed its standard automated function of retarding the engines to flight idle. While this was normal system logic for the MD-11, it proved detrimental in these specific conditions as the aircraft was heavy and experiencing a sudden loss of headwind. This led to a 20-knot drop in airspeed and a rapid increase in the sink rate. The captain did not apply corrective thrust or sufficiently flare the aircraft to cushion the impact. The resulting vertical force exceeded the structural design limits of the right main landing gear and wing spar.
Final Conclusions
The Hong Kong Civil Aviation Department concluded the primary cause was the commander's failure to arrest the high rate of descent at 50 feet. Contributory factors included the failure to appreciate the combination of reducing airspeed and increasing descent rate while thrust was at idle, and the failure to apply power to counteract the sink rate. The investigation also noted that variations in wind speed and direction below 50 feet likely resulted in a momentary loss of headwind component, which, combined with the early retardation of thrust, led to the critical loss of airspeed just before touchdown.
Photographic Evidence (1)
Video Analysis
Pilot Error or Impossible Conditions? The Crash of Flight 642 — An analysis of China Airlines Flight 642's attempt to land in Hong Kong during Tropical Storm Sam, exploring the crew's decision-making and the MD-11's handling characteristics.
If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Autothrottle
The system retarded the engines to flight idle at 50 feet, which contributed to a rapid loss of airspeed when combined with wind variations.
Right Main Landing Gear
The gear collapsed under the extreme vertical load of the hard landing, leading to the failure of the right wing spar.
MD-11 Wing Structure
Designed to fail in a way that prevents fuel tank rupture, but the severity of the roll caused the wing to separate and the fuselage to flip.
Interesting Facts
- 01The aircraft was an MD-11 previously operated by Mandarin Airlines and still wore its subsidiary livery.
- 02The crosswind component at the time of landing was approximately 26 knots, exceeding the aircraft's demonstrated limit of 24 knots for the prevailing conditions.
- 03The aircraft was landing at a weight of 443,000 lbs, which was below the maximum allowable landing weight of 458,000 lbs.
- 04Three passengers died: two at the scene and one five days later in the hospital.
- 05A total of 219 people were admitted to the hospital, with 50 sustaining serious injuries.
- 06This was the first fatal accident at the new Hong Kong International Airport since its 1998 opening.
Safety Actions & Advisories
MD-11 Landing Training
Enhanced simulator training for MD-11 crews was implemented, specifically focusing on high sink rate recovery and the importance of monitoring airspeed and descent rate during the flare in gusty conditions.
Crosswind Limitations
A review of airline crosswind limitations was conducted to ensure stricter adherence to safety margins during tropical storm conditions and wet runway operations.
Known Controversies & Unanswered Questions
Dispute over Aircraft Weight Factor
Reference ↗A Board of Review appointed in 2002 rejected the original report's finding that the aircraft's high landing weight was a significant contributory cause, arguing that the extra weight may have actually provided more inertia and stability.