UPDATE 1-U.S.-bound United Airlines lands back in London after 'maintenance issue'
December 17, 2014 at 10:59 AM EST
LONDON, Dec 17 (Reuters) - A U.S.-bound United Airlines flight with 240 people aboard has returned to London's Heathrow airport, according to flight-tracking website Flightradar24, after an unspecified maintenance issue forced it to circle for hours above the English Channel on Wednesday.