What happened
On May 2, 2010, an Airbus A319, registration D-AKNH, operating flight LH1835 from Budapest to Milan Malpensa, encountered severe weather conditions during its approach to runway 35R. The aircraft experienced significant windshear, with a 20-knot tailwind component transitioning to a 20-knot headwind component below 2,000 feet. Due to the instability caused by these conditions, the crew executed a missed approach.
As weather conditions at Malpensa continued to deteriorate, the crew requested a diversion to Milan Linate. During the period between the diversion request and the final authorization, the crew repeatedly notified Milan ACC of critically low fuel levels, warning that an emergency declaration would be imminent. At 19:34 UTC, while approximately 13 NM from Linate, the crew declared a "Mayday" due to low fuel, stating they had approximately 30 minutes of flying time remaining. The aircraft subsequently landed at Linate at 19:42 UTC with approximately 1,100 kg of fuel remaining.
The investigation
The ANSV investigation focused on the 17-minute delay between the initial diversion request and the authorization to land at Linate. The investigation examined communications between Milan ACC, Linate Tower, the SEA Duty Manager, and the airline's ground handling agent.
Investigators found that while parking stands were available at Linate, the authorization process was stalled by a lack of coordination. The ground handling agent initially suggested diverting the flight to Turin instead of Linate, and the SEA Duty Manager was awaiting confirmation from the handler regarding ground services. This lack of timely information prevented air traffic controllers from promptly accepting the diversion, forcing the crew to manage a rapidly depleting fuel supply.
Findings
- The primary cause of the serious occurrence was the failure to promptly accept the crew's request to divert to Milan Linate.
- This delay was driven by a lack of coordination between Milan ACC, Linate Tower, the airport manager (SEA), and the airline's handling agent.
- The ground handler's suggestion to divert to Turin was never communicated to the flight crew.
- The delay in confirming ground service availability led the crew to reach their final reserve fuel limits, necessitating the declaration of a fuel emergency.