Transatlantic flights resume

Armed police stand guard at Heathrow Airport on Friday

LONDON, England (CNN) -- The first transatlantic flight from Britain to the U.S. since Tuesday's attacks left London's Heathrow airport on Friday.

American Airlines flight 087 was scheduled to leave at 10:05 a.m. (0905 GMT) but was delayed and took off just before noon. American said it hoped to have a limited number of flights leaving Heathrow and Gatwick airports near London throughout the day.

No further details of timings have currently been made available, and passengers are advised to call the airline.

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American Airlines said its flight from Chicago landed at Heathrow at around 8:30 a.m. and that another Chicago flight had arrived at Birmingham.

The carrier said it intended to operate three morning flights from Heathrow to Chicago, Miami and Los Angeles.

"We may be able to have more U.S.-bound flights later in the day," a spokesman told the UK's Press Association.

Three Air Canada flights -- from Toronto, Montreal and Ottawa - arrived at Heathrow on Friday morning.

The airline was operating 15 flights, two more than usual, from Heathrow to Canada on Friday -- seven to Toronto, three to Vancouver, two to Calgary and one each to Ottawa, Halifax and Montreal.

Virgin Atlantic said it hoped to restart its Gatwick to Toronto flights soon and would be making an announcement later on Friday.

British Airways said on Friday it would resume flights to Canada but that its flights to the U.S. remained cancelled.

BA flights to Montreal, Vancouver and Toronto were to leave London on Friday following approval by Canadian authorities. Full service to Canada was expected to resume Saturday.