Air Canada flight's emergency return

An Air Canada flight bound for Toronto was forced to perform a dramatic emergency return to London Heathrow shortly after departure.

The Boeing 777-300ER issued a 'Squawk 7700' general emergency alert while flying over the Atlantic Ocean.

The aircraft performed a U-turn and landed safely back at the airport, where it was met by emergency services.

Airline officials have not yet confirmed the specific nature of the technical issue that prompted the emergency landing, and passengers were re-accommodated on alternative flights.