Heathrow was subject to delays and some cancellations following a fire on an Ethiopian Airlines Dreamliner on Friday.
Both Heathrow runways were closed for about 90 minutes after the fire, reported at 4.30pm. No passengers were on board the aircraft at the time.
Delays continued into the evening and passengers were told to check the status of their flight before travelling to the airport.
Ethiopian Airlines said: “Smoke was detected from Ethiopian Airlines B787 aircraft with registration number ET-AOP, which was parked at London Heathrow airport for more than eight hours.
“The aircraft was empty when the incident was observed. The cause of the incident is under investigation by all concerned. Further statement will be issued in due course, as we receive more information.”
A Heathrow spokesperson said there had been an “onboard internal fire”.
Boeing said it was aware of the incident and had staff on scene. A statement said: “We’re working to fully understand and address this.”
Meanwhile, a Thomson Airways Dreamliner bound for Orlando was forced to turn back to Manchester airport after it developed a mid-flight ‘technical issue’.
A spokesman for Thomson said the return to Manchester was a precaution and passengers were being moved to an alternative aircraft.
Gatwick also experienced minor delays on departing flights as it helps manage diversions from Heathrow.
Dreamliners worldwide were grounded at the start of the year because of battery malfunctions. Flights resumed in April.