The McDonnell Douglas MD-11 operating the flight, registered B-150, had a complicated history with China Airlines. Delivered to the airline in October 1992, it had been passed to China Airlines' subsidiary Mandarin Airlines in 1993, then returned to China Airlines in March 1999 — just five months before the accident. At the controls that evening was Captain Gerardo Lettich, a 57-year-old Italian national who had joined China Airlines in 1997 after flying for a major European carrier. He carried 17,900 total flight hours, with 3,260 of those on the MD-11. Beside him was First Officer Liu Cheng-hsi, 36, a Taiwanese national who had been with the airline since 1989 and had logged 4,630 hours, including 2,780 on the MD-11. Both were experienced. The weather, as the approach unfolded, would test that experience in ways the instruments alone could not fully communicate.

Flight 642 had originated in Bangkok and was routing through Hong Kong to Taipei. Because severe weather had been forecast, the crew had loaded extra fuel in case a diversion to Taipei became necessary — that decision brought the aircraft's landing weight to 429,557 pounds, within a fraction of one percent of its maximum certified landing weight of 430,000 pounds. The heavier the aircraft, the more runway and the more precision the landing requires. At 700 feet on the approach, a wind check was relayed to the crew: winds gusting from 320 degrees, 28 to 36 knots. The crosswind component worked out to 26 knots gusting to 33 — against a tested aircraft limit of 35. The margin was narrow. Four earlier flights had attempted and abandoned approaches at Hong Kong that evening; five others had diverted outright. Flight 642 continued. During the final flare — the last few feet before touchdown, where a pilot raises the nose slightly to arrest the descent — the rate of descent was not arrested. The aircraft landed hard on its right main gear. The No. 3 engine, mounted on the tail of the trijet, struck the runway surface. The right wing separated from the fuselage. With the left wing still generating lift and the right wing gone, physics took over: the fuselage rolled onto its right side and then over onto its back, coming to rest inverted in the grass strip beside the runway, 3,500 feet from the runway threshold. Spilled fuel caught fire.

Rescue vehicles reached the inverted aircraft quickly, suppressing the fire in the rear section as emergency teams worked through rain and debris to reach the passengers trapped inside. The conditions were difficult — an overturned widebody, burning at the rear, in a tropical storm. Two passengers pulled from the wreckage were pronounced dead on arrival at hospital. A third died five days later. Of the remaining 312 people who survived, 50 sustained serious injuries and 153 sustained minor ones. All 15 crew members survived. The crash was recorded by bystanders in a passing car, one of the first aviation accidents captured on bystander video in Hong Kong. Those three lives — their names are not recorded in the public investigation documents — represent the human weight of what the official report would later describe in the language of aerodynamics and crosswind vectors.

Hong Kong's Civil Aviation Department investigated the accident for five years, releasing its final report in December 2004. The investigation determined that the primary cause was pilot error — specifically, the failure during the final flare to arrest the aircraft's rate of descent, combined with the aircraft landing with its right wing slightly low. China Airlines disputed the finding of pilot error. The crash was the first fatal accident at Chek Lap Kok since the airport opened in July 1998, and it arrived at a moment when the MD-11's handling characteristics on landing were already drawing scrutiny: the aircraft had been involved in several serious landing incidents across its operational history. Flight 642 became one of only two hull losses of passenger-configured MD-11s, the other being Swissair Flight 111, which had killed all 229 people on board the previous year. The lessons encoded in what happened on that grass strip at Chek Lap Kok — about crosswind limits, about landing weight, about the gap between published limits and operational reality — passed into aviation training materials and flight manuals worldwide.