British Airways Boeing 777 at Heathrow on 17th January 2008 – Double Engine Failure

On 17th January 2008, a British Airways Boeing 777-236ER, registration G-YMMM, flying from Beijing Capital International Airport (PEK) to London Heathrow (LHR), experienced a rare and significant mechanical failure as it approached Heathrow. Just five minutes before the scheduled landing, both of the aircraft’s Rolls-Royce Trent 800 engines failed to respond to commands for increased thrust. This resulted in the aircraft gliding in an uncontrolled descent, crashing just short of the runway. The quick actions of the flight crew prevented a major catastrophe, with all 152 people on board surviving the impact, although 47 passengers sustained injuries.

Overview of the Incident

The Boeing 777, a twin-engine wide-body aircraft, was nearing the end of its long-haul flight and preparing for final approach into Heathrow’s runway 27L when the engines, which were running normally up to that point, suddenly stopped producing adequate thrust. At a height of just 720 feet, when the aircraft was descending over west London, the pilots attempted to increase engine power for landing but were met with an unexpected failure. The engines remained operational but failed to respond to increased throttle commands, leaving the plane without the necessary thrust to maintain its approach path.

Captain Peter Burkill, along with his co-pilot, Senior First Officer John Coward, immediately recognized the gravity of the situation. They decided to raise the flaps to reduce drag and maintain as much altitude as possible. The aircraft continued to lose altitude and speed, eventually touching down in the grass approximately 330 meters short of the runway threshold. Upon impact, the nose landing gear collapsed, and the aircraft slid across the ground, coming to a halt on the runway perimeter road.

Despite the impact, there was no post-crash fire, which greatly contributed to the survival of the passengers and crew. This lack of fire was fortunate, given that the plane had full fuel tanks for the long-haul flight.

Detailed Analysis of Engine Failure

The most critical component of this incident was the failure of the aircraft’s Rolls-Royce Trent 800 engines to provide thrust during the final approach. An investigation led by the UK’s Air Accidents Investigation Branch (AAIB) revealed that the failure was caused by ice crystals forming in the fuel system. These ice crystals accumulated during the cruise phase of the flight, when the aircraft was flying through extremely cold air over Siberia and northern Europe.

The fuel for the Boeing 777, stored in its wings, had cooled significantly during the flight, dropping to temperatures as low as -34°C (-29°F). Even though jet fuel, specifically Jet-A1, can remain liquid at these temperatures, water naturally present in the fuel can freeze into ice crystals. The ice that formed did not immediately affect engine performance during cruise but gradually built up in the fuel system.

Specifically, the ice accumulated in the fuel-oil heat exchangers (FOHEs), which are responsible for transferring heat between the hot engine oil and cold fuel to prevent icing. When the pilots called for an increase in thrust during the final approach, the higher fuel flow rate dislodged the ice crystals, which subsequently blocked the fuel-oil heat exchangers in both engines. This blockage restricted fuel flow to the combustion chambers, leading to insufficient thrust generation when it was needed most.

Fuel-Oil Heat Exchanger Design and Function

The fuel-oil heat exchanger in the Rolls-Royce Trent 800 engine is designed to transfer heat from the engine oil, which operates at temperatures around 150°C (302°F), to the fuel, which can reach subzero temperatures in flight. This heat transfer is essential to prevent fuel from freezing or forming ice crystals in the fuel lines. However, the FOHE in the Boeing 777’s engines was not adequately designed to handle the type of fine ice crystals that formed during this flight.

The FOHE had small channels through which fuel passed and was heated by the adjacent oil. These channels became clogged with ice crystals, which restricted fuel flow when maximum thrust was needed for landing. Rolls-Royce and Boeing had not previously encountered this specific issue, as the ice buildup was gradual and the blockage occurred only when fuel flow rates were increased.

Crew Response and Handling of the Emergency

The actions of the flight crew were instrumental in averting what could have been a much larger disaster. Captain Peter Burkill and First Officer John Coward immediately recognized the engine power loss and took steps to maximize the aircraft’s glide distance. They raised the flaps to reduce drag, which allowed the aircraft to maintain altitude for as long as possible. The pilots had limited time—approximately one minute—from the moment they realized the engines were unresponsive to the moment the aircraft touched down.

The final moments of the descent were a delicate balance between maintaining the aircraft’s forward momentum and preventing it from stalling. The decision to raise the flaps helped slow the descent rate, and the crew’s calm handling of the situation ensured that the aircraft remained controllable until impact.

Investigation and Findings

The AAIB investigation into the crash was extensive, taking almost two years to complete. The final report, issued in 2010, concluded that the engine failure was caused by the formation of ice crystals in the fuel system, specifically within the fuel-oil heat exchanger. The report highlighted several key findings:

1. Fuel Temperature and Ice Formation: The fuel had cooled to very low temperatures during the cruise portion of the flight, which allowed ice crystals to form in the fuel system. The ice remained suspended in the fuel until it reached the heat exchanger, where it accumulated and eventually blocked the flow of fuel to the engines.

2. Fuel-Oil Heat Exchanger Design: The design of the fuel-oil heat exchanger in the Rolls-Royce Trent 800 engines was found to be susceptible to blockage by ice crystals. The investigation revealed that the FOHE was not adequately tested for this particular failure mode during the engine’s certification process.

3. Absence of Engine Warnings: Despite the ice buildup in the fuel system, no warnings or alerts were generated in the cockpit to notify the crew of the impending engine failure. This lack of warning limited the crew’s ability to take preventive action before the engines lost power.

4. Post-Incident Modifications: Following the investigation, Boeing and Rolls-Royce developed and implemented a redesigned fuel-oil heat exchanger for all Trent 800 engines. This modification involved increasing the size of the heat exchanger’s fuel channels to prevent ice blockage and improve fuel flow under extreme conditions.

Maintenance and Design Modifications

In the aftermath of the crash, both Boeing and Rolls-Royce worked closely with aviation regulatory bodies to develop and implement modifications to the fuel systems of all Boeing 777s equipped with Rolls-Royce Trent 800 engines. The redesigned FOHE incorporated larger fuel flow passages and additional measures to prevent the accumulation of ice in the fuel system.

In addition to the hardware modifications, new operational procedures were introduced to help prevent similar incidents. These procedures included guidance for pilots on managing fuel temperatures during long-haul flights and recommendations for monitoring fuel system performance in cold weather conditions.

Impact on Aviation Safety

The British Airways Boeing 777 incident at Heathrow served as a major lesson for the aviation industry regarding the dangers of ice formation in fuel systems, especially during long-haul flights over extremely cold environments. The modifications to the fuel-oil heat exchangers were not limited to Rolls-Royce Trent 800 engines but also encouraged a reevaluation of similar systems across various aircraft models to ensure they could handle the extreme conditions that occur during high-altitude, long-duration flights.

The aviation safety community responded with increased awareness and preventive measures. Regulators such as the Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA) issued directives to operators of affected aircraft models, requiring the installation of the new fuel-oil heat exchangers and instituting new protocols for fuel system monitoring.

Lessons Learned for Aircraft Design and Operation

This incident underscored the importance of comprehensive testing during aircraft and engine certification. The blockage of the FOHE was not anticipated during the design phase, highlighting the need for exhaustive tests that account for rare but severe environmental conditions, such as fuel icing. Future testing procedures for aircraft systems were expanded to simulate more extreme and varied conditions, ensuring that critical systems can function properly under all circumstances.

Another significant lesson was the role of data monitoring and real-time alerts for pilots. The fact that the pilots received no prior warning about the ice buildup before the engines began losing power showed the need for better fuel system monitoring. As a result, aircraft manufacturers and avionics companies developed systems that allow for real-time monitoring of fuel temperatures and conditions, with alerts that warn pilots about potential fuel icing long before it becomes a critical issue.

Training and Simulation

Following the Heathrow incident, pilot training programs incorporated new scenarios that mirrored what happened on British Airways Flight 38. Simulators were updated to train pilots on how to respond to situations involving engine power loss due to fuel icing or other similar malfunctions. This helped ensure that crews could react even faster and more effectively to similar failures, potentially saving even more lives.

Conclusion: Enhancing the Safety Net

The crash of British Airways Flight 38 remains a landmark event in the aviation industry, not just for the rarity of the mechanical failure but for the successful post-incident responses that have significantly improved safety standards. While all 152 people survived, the incident brought attention to hidden vulnerabilities in aircraft systems, leading to essential changes in both engineering practices and operational procedures.

The lessons from this event serve as a reminder that aviation safety is a continually evolving field. By thoroughly investigating incidents like these, the industry can make the necessary improvements to ensure that similar failures do not occur again. As a result, the crash of Flight 38 has left a lasting legacy, one that has ultimately enhanced the safety of commercial aviation for passengers and crew worldwide.

This event also highlighted the importance of collaboration between airlines, manufacturers, and regulatory authorities in resolving safety concerns. Through their swift responses and changes to fuel system design, Boeing and Rolls-Royce helped prevent further incidents of this nature, ultimately contributing to the continued confidence in air travel safety today.

The Future of Icing-Related Research

In addition to the immediate changes implemented, ongoing research into icing-related hazards continues to evolve. Technological advancements have provided better monitoring tools, as well as innovations in aircraft design and material sciences that help prevent ice from affecting critical systems. In conjunction with the lessons learned from British Airways Flight 38, the development of more resilient aircraft ensures that the flying public benefits from a continuously safer aviation environment.

Reflection on Crew Performance

One of the most praised aspects of this incident was the professionalism and quick thinking of the flight crew, particularly Captain Burkill and First Officer Coward. Their decision to raise the flaps and maintain control of the aircraft during its final moments in the air directly contributed to the safe evacuation and survival of all passengers. This incident demonstrated the importance of effective crew resource management (CRM) and has been used as a case study in flight safety training worldwide.

The incident at Heathrow on 17th January 2008 is a powerful reminder that even with the most advanced technology, human expertise and training remain essential to ensuring safety in the skies. Through a combination of engineering enhancements, regulatory changes, and improved pilot training, the aviation industry continues to evolve, striving to prevent incidents like this from happening again.