What happened
On 8 February 2005, an Airbus A340-642, registration G-VATL, was operating a passenger flight from Hong Kong to London Heathrow. During the pre-flight phase, the crew noted a failure in one of the Fuel Control Monitoring Computers (FCMC). While the crew attempted a reset during cruise, the issue persisted.
While cruising at FL380 over Dutch airspace, the number 1 engine suddenly lost power. Upon investigation, the crew discovered that the fuel content in the inner 1 fuel tank was reading zero. Shortly after, the number 4 engine power began to fluctuate, and the inner 4 fuel tank also indicated zero fuel. The crew declared a 'MAYDAY' and diverted to Amsterdam Schiphol Airport. During the diversion, the crew attempted manual fuel transfers, but they could not immediately confirm the fuel status via the ECAM. The aircraft landed safely in Amsterdam with no fatalities and no injuries to the 18 crew members or 293 passengers.
The investigation
The AAIB examined the fuel system architecture and the regulatory requirements for large transport category aircraft. The investigation focused on why the crew was not alerted to the depleting fuel levels in the engine feed tanks. Investigators reviewed EASA CS-25 and FAA FAR-25 regulations, noting that unlike smaller aircraft and rotorcraft, these regulations do not mandate a low fuel level warning for large aeroplanes. The investigation also looked into the functionality of the FCMC and the visibility of fuel status on the aircraft's synoptic displays.
Findings
- The crew was unaware of the critical fuel levels because current EASA CS-25 and FAA FAR-25 regulations do not require a low fuel level warning for large aircraft.
- While a fuel quantity indicator is required, a specific low-level alarm for engine-feed tanks is absent from the standard requirements for this aircraft class.
- The complexity of modern glass cockpits and automated fuel sequencing can make it difficult for crews to identify fuel depletion through synoptic displays alone without an automated alert.
- The failure of the FCMC contributed to the difficulty in monitoring the fuel system accurately.
Safety action
- Safety Recommendation 2005-108: Recommended that EASA introduce a requirement for a low fuel warning system for each engine feed fuel tank in CS-25, which must be independent of the fuel control and quantity indication systems.
- Safety Recommendation 2005-109: Recommended that the FAA introduce a similar requirement for a low fuel warning system in FAR-25, also independent of the primary fuel monitoring systems.
- Safety Recommendation 2005-110: Recommended that EASA review existing CS-25 and JAR-25 certified aircraft to ensure any installed low fuel warning systems are independent of the fuel control and quantity indication systems.
- Safety Recommendation 2005-111: Recommended that the FAA review FAR-25 certified aircraft to ensure the independence of any existing low fuel warning systems.