An official investigation into a fire on an Ethiopian Airlines Boeing 787 Dreamliner at Heathrow has concluded it was caused by an electrical fault with a battery.
The aircraft was parked at Heathrow in 2013 but the incident caused both of the airport’s runways to be closed as emergency services dealt with the blaze.
UK investigators into the fire have said it would have been difficult to tackle had it taken place while the aircraft was in flight.
An Air Accidents Investigation Branch (AAIB) report has concluded the fire was caused by wires from a lithium battery that had become trapped under a cover.
This caused the battery to short circuit and overheat which resulted in flammable materials leaking and igniting in the ceiling of the cabin.
A safety mechanism installed that should have prevented the overheating and spread of flames proved inadequate, the report said.
The report notes that firefighters were hampered by both the location of the battery and the fact that its presence was not indicated in information documents about the aircraft.
It added this would have also meant crew would not have been alerted about a similar fire for some time were it to have started mid-flight.
The battery was associated with a beacon tracking device installed to find missing aircraft and the AAIB report has led to calls for use of such equipment to be reviewed.
Concerns remain about the continued use of such batteries for other onboard equipment.
The Ethiopian Airlines fire marked a low point in the introduction of the Dreamliner which was delayed by three years and grounded in 2013 after similar problems with other aircraft.