A cargo plane that departed Heathrow for Hong Kong lost power to key electrical systems shortly after takeoff and later went into a steep, high-speed descent, according to a UK Air Accidents Investigation Branch (AAIB) report published on Thursday 3 September. No passengers were on board and the aircraft landed safely, but investigators have issued four safety recommendations after tracing the fault to water that entered the aircraft before departure.
The AAIB bulletin says the Boeing 747-433 freighter, registered G-ONEE, suffered electrical problems beginning during its takeoff roll from Heathrow on 8 February 2024, which worsened as it climbed. The aircraft lost two of its AC electrical buses, triggering a string of failure messages for the flight crew, according to the report published on gov.uk. The crew declared a PAN and began diverting to Amsterdam Schiphol Airport.
The situation escalated when a pressurisation problem forced the crew to descend through icing conditions. With the aircraft's pitot tube heating also knocked out by the electrical failure, the airspeed sensors froze, causing all three cockpit airspeed indicators to show an incorrectly low speed. The autopilot, still engaged, responded by pitching the aircraft's nose down, and the jet entered a descent of more than 6,000 feet a minute with its nose pitched 7.6 degrees down, the AAIB found. The Evening Standard, which was first to report the AAIB findings, said the descent caused the aircraft to exceed its maximum permitted speed by 18 knots before it emerged from the icing conditions and the crew regain