British Airways Flight 38

British Airways Flight 38 was a scheduled international passenger flight from Beijing Capital International Airport in Beijing, China, to Heathrow Airport in London, United Kingdom, an 8100 km trip. On 17 January 2008, the Boeing 777 aircraft crash-landed short of runway 27L at Heathrow. Of the 152 people on board, 47 were injured, 1 of them seriously. The aircraft (registered as G-YMMM) sustained heavy damage and was written off as a result, becoming the first hull loss of a Boeing 777.

The accident was investigated by the Air Accidents Investigation Branch (AAIB) and their final report was issued in February 2010. Ice crystals in the jet fuel were blamed as the cause of the accident, clogging the fuel/oil heat exchanger (FOHE) of each engine. This restricted fuel flow to the engines when thrust was demanded during the final approach to Heathrow. The AAIB identified this rare problem as specific to Rolls-Royce Trent 800 engine FOHEs. Rolls-Royce developed a modification to the FOHE; the European Aviation Safety Agency (EASA) mandated all affected aircraft to be fitted with the modification before 1 January 2011. The US Federal Aviation Administration noted a similar incident occurring on an Airbus A330 fitted with Rolls-Royce Trent 700 engines and ordered an airworthiness directive to be issued, mandating the redesign of the FOHE in Rolls-Royce Trent 500, 700, and 800 engines.

Accident

Flight 38 departed from Beijing at 02:09 Greenwich Mean Time (GMT), flying a route that crossed Mongolia, Siberia, and Scandinavia, at altitudes between flight level 348 and 400—approximately 34,800 and 40,000 ft, and in temperatures between −74 °C and −65 °C; the total air temperature has been estimated around −37 °C. Aware of the cold conditions outside, the crew monitored the temperature of the fuel, with the intention of descending to a lower and warmer level if any danger of the fuel freezing arose.

This did not prove necessary, as the fuel temperature never dropped below −34 °C, still well above its freezing point.

Although the fuel itself did not freeze, small quantities of water in the fuel did.

Ice adhered to the inside of the fuel lines, probably where they ran through the pylons attaching the engines to the wings.

This accumulation of ice had no effect on the flight until the final stages of the approach into Heathrow, when increased fuel flow and higher temperatures suddenly released it back into the fuel. This formed a slush of soft ice that flowed forward until it reached the fuel/oil heat exchangers (FOHEs) where it froze once again, causing a restriction in the flow of fuel to the engines.

The first symptoms of the fuel-flow restriction were noticed by the flight crew at an altitude of 720 ft and 2 mi from touchdown, when the engines repeatedly failed to respond to a demand for increased thrust from the autothrottle. In attempting to maintain the instrument landing system glide slope, the autopilot sacrificed speed, which reduced to 108 kn at 200 ft. The autopilot disconnected at 150 ft, as the first officer took manual control. Meanwhile, the captain reduced the flap setting from 30 to 25° to decrease the drag on the aircraft and stretch the glide.

At 12:42, the 777 passed just above the residential street of Myrtle Avenue, then immediately after overflew traffic on the A30 and the airport's Southern Perimeter road and landed on the grass about 270 m short of runway 27L. The captain declared an emergency to air traffic control a few seconds before landing. The decision to raise the flaps allowed the plane to glide beyond the ILS beacon within the airport perimeter, thus avoiding more substantial damage.

During the impact and short slide over the ground, the nose gear collapsed rearward, the right main gear broke off and fully separated from the aircraft, puncturing the central fuel tank and penetrating the passenger oxygen supply, causing a major fuel leak and the release of oxygen gas from adjacent compartments. The right main landing gear also penetrated the cabin space, causing the sole serious injury in this accident to a passenger in seat 30K before striking the right-hand horizontal stabiliser's leading edge. The left main gear was pushed up through the wing root, as it was designed to do in case of failure due to excessive vertical load. The aircraft came to rest on the threshold markings at the start of the runway. 6750 kg of fuel leaked, but no fire started. One passenger received serious injuries (concussion and a broken leg), and four crew members and eight passengers received minor injuries.