British Airways Flight 38 was a scheduled international passenger flight from Beijing Capital International Airport, China to London Heathrow Airport, United Kingdom on 17th January 2008.
The Boeing 777-200ER crashed just short of the runway while landing at Heathrow with 136 passengers and 16 crew on board.
This was the first time in the aircraft type's history that a Boeing 777 was declared a hull loss and subsequently written-off.
As the crew was coming into land at London Heathrow airport at around 720ft, the first symptoms of the fuel flow restriction were noticed. The aircraft engines repeatedly failed to respond to a demand for increased thrust from the autothrottle.
As the aircraft autopilot tried to maintain the Glideslope, the aircraft speed significantly reduced.
The copilot took manual control at 150ft and at the same time, the captain reduced the flap setting from 30 degrees to 25 degrees to decrease the drag on the aircraft and stretch the glide. The decision to raise the flaps had a direct consequence in allowing the aircraft to safely fly over the A30 without crashing into the busy route.
On impact, the aircraft nose gear collapsed, the right main gear separated from the aircraft, penetrating the central fuel tank and cabin space, and the left main gear was pushed up through the wing.
The aircraft came to rest on the threshold markings at the start of the runway. A significant amount of fuel leaked, but there was no fire. Four crew members and eight passengers received minor injuries, and one passenger received serious injuries
The Air Accident Investigation Branch AAIB issued a full investigation report on 9 February 2010. It concluded that:
The investigation identified that the reduction in thrust was due to restricted fuel flow to both engines.
The investigation identified the following probable causal factors that led to the fuel flow restrictions:
Accreted ice from within the fuel system released, causing a restriction to the engine fuel flow at the face of the FOHE, on both of the engines.
Ice had formed within the fuel system, from water that occurred naturally in the fuel, whilst the aircraft operated with low fuel flows over a long period and the localized fuel temperatures were in an area described as the 'sticky range'.
The FOHE, although compliant with the applicable certification requirements, was shown to be susceptible to restriction when presented with soft ice in a high concentration, with a fuel temperature that is below −10 °C and a fuel flow above flight idle.
Certification requirements, with which the aircraft and engine fuel systems had to comply, did not take account of this phenomenon as the risk was unrecognized at that time.