The UK Air Accidents Investigation Branch has traced a serious in-flight electrical event on a One Air Boeing 747-400 freighter to water ingress after maintenance left the forward left door open in rainy weather. The converted cargo aircraft, operating from London Heathrow to Hong Kong, suffered failures affecting generator control units and pitot tube heating, forcing the crew to deal with unreliable airspeed indications and an abnormal descent path.
The incident occurred on 8 February 2024, but the final report has only now been published and distributed through aviation media. No one was injured and the aircraft was not damaged, yet the sequence exposed how a ground-handling lapse can cascade into a major operational upset.
Investigators linked the water entry to overnight maintenance, during which the L1 door remained open as rain and wind blew towards it. The report led to four safety recommendations for Boeing and Israel Aerospace Industries, focusing on closer inspection of protective covers, seals and possible entry points around the electrical equipment area.
The findings are especially relevant for older freighter conversions, where sealing vulnerabilities can develop over time. They also underline the need for strict door discipline and thorough checks in wet conditions when maintenance activity overlaps with aircraft dispatch.