Ice In Fuel Was Most Likely Cause Of BA Crash

Thursday 4th September 2008

It seems like a long time since a British Airways Boeing 777 crashed at Heathrow Airport and finally there is a strong indication as to what caused the crash landing.

A BA Boeing 777 coming in to land

Initial speculation suggested that the aircraft had flown through excessively cold conditions when over Siberia on its route from Beijing to Heathrow Airport. It is believed by the Air Accident Investigation Branch that the fuel flow pressure dropped when the aircraft was only moments from touching down at Heathrow Airport. This in turn caused the engines to lose power and prevent the pilot from being able to obtain enough power to make a regular landing. However it is still not known how the ice could have formed despite the cold Siberian temperatures that the jet had flown through.

Aviation fuel always contains a certain quantity of water within it, upon inspection however investigators found that the aircraft had a very low water content compared to a regular Boeing 777 fuel load.

Investigators have moved to quash rumours that the fuel itself froze or even changed to a paste or wax. Sensors onboard the Boeing 777 indicate that the lowest temperature the fuel experienced on the flight was-34C (-29F), however aviation fuel should not freeze until it experiences temperatures as low as -57C (-70F). It has also confirmed that despite the low temperatures the fuel experienced on the flight it was not an isolated case, and airlines often find themselves in these temperatures and have no issues with fuel freezing.

Testing still continues in the UK and US as to the cause of the crash with investigators and engineers desperate to find a definitive cause as to the crash which will remove some of the doubt and worry over the Boeing 777 that has experienced computer glitches in the past causing in-flight problems despite being regarded as a highly reliable airliner.

Tests have been carried out on aircraft systems identical to the Boeing 777 that crashed to see the effect that ice has on a fuel system and engine. Investigators have found that whilst they could introduce ice that affected the performance of the engine the quantities that had to be added were much higher than expected. It remains a mystery as to how that quantity of ice could have formed in the aircraft fuel tank and system.

The main theory currently being worked on is that ice was allowed to gradually form in the fuel tank and somehow managed to clog the fuel system as the aircraft came into land. As a result of the finding three recommendations have been made by the report;

1. Interim measures are to be introduced to ensure that the chances of ice forming on Boeing 777 aircraft using the Trent 800 engine is reduced.

2. The chances of a similar accident occurring to another aircraft type should be considered and acted upon.

3. Investigate the potential for new engines to be introduced.

As far as air accident investigation goes this crash and scenario is extremely rare which is why so much time and effort has gone into investigating the possible causes of the crash. The investigation team first suspected fuel problems when they examined the fuel pumps of the aircraft and noticed irregular cavitation which alerted them to a problem with fuel. The report released by the team says that in 6.5 million flight hours this has been the first example of this problem occuring which indicates the rareness of such an incident.

Fortunately the incident resulted in no fatalities and the worst injury sustained was a passenger who suffered a broken leg when evacuating the aircraft via the emergency slides.

If you would like to read the report you can find the PDF file on the Air Accident Investigation Branch website (you may need to install Adobe Reader to be able to open the file).