The Air Accidents Investigation Branch published a report on 3 September 2026 on a Boeing 747-433 freighter, G-ONEE, due to fly from London Heathrow to Hong Kong on 8 February 2024. According to the report, water ingress into Generator Control Units 1 and 4 isolated AC buses 1 and 4, producing multiple failure messages and the loss of all pitot tube heating. The crew declared a PAN and diverted to Amsterdam Schiphol.

During a descent, the aircraft entered icing conditions and the pitot tubes froze, so all three airspeed indicators showed an erroneously low speed. The autopilot pitched nose-down to 7.6° with a 6,240 ft/min descent rate before the aircraft left the icing conditions; the descent resulted in an 18 kt overspeed. The crew declared a MAYDAY and landed safely at Schiphol.

The report says water entered the main cargo deck before departure because the L1 door was left open during rain. The exact path to the GCUs could not be determined, but weaknesses in water-ingress protection were found. The AAIB made four safety recommendations on maintenance concerns, citing no requirement for repetitive inspection of the drip shield or detailed inspection of floor panel seals and related components.