This is breaking news with limited information available. American Airlines flight 109 (N723AN, a Boeing 777) from London Heathrow to Los Angeles has turned back for London over Iceland and declared an emergency squawking 7700.
Initial information obtained from social media posted by passengers on board states 7 cabin crewmembers and many passengers are sick. Hypoxia is also likely, so the emergency may be a pressurization issue.
We’ll update this article when more information becomes available.
UPDATE 12:10pm EDT: The flight has landed safely back in London. More news as it becomes available.
UPDATE 5:44pm EDT: News from passengers tweeting and those on the ground are saying fumes were being inhaled in the cabin which may have caused the illnesses and the crew had decided to return to London rather than diverting to Iceland.
UPDATE 8:40am 1/28/16: It has been suspected that fumes were to blame for the illnesses onboard. Teams have gotten to work to find the source of the problem: “Ran both engines/apu systems and cabin air quality check came ok. Replacing recirc fans and filters and doing a flight test after to confirm air quality check.”