On 17 December it appears that United’s flight from London to Newark had a technical problem on take-off. Several hours later after dumping fuel over the English Channel it returned to Heathrow.
The 767-400 left at 11am and returned back at 4pm. The Daily Mail has a number of reports from some of the 200 passengers on board.
Most passengers appear to have been accommodated in hotels and the flew on the next day.