Pilots of a Boeing 777 from London to San Francisco is turning around over North of UK.
United Airlines flight UA939 departed London Heathrow at 16:21 BST for a 10-hour flight to San Francisco, CA.
Pilots of the Boeing 777-200ER (registration N788UA) declared an emergency less than one hour into the flight due to a mechanical issue.
This aircraft is 28 years old, it was delivered to United on July 1997.
UPDATE 17:30 BST
The aircraft is still holding 31,000 feet and circling.
UPDATE 17:36 BST
The airline is announcing a new estimated departure 2 jours and 53 minutes late.
UPDATE 17:50 BST
We have confirmation the flight is returning to London Heathrow and dumping fuel due to right hand engine issue.
UPDATE
Flight has been canceled.
