Flight UA986 from Charles De Gaule in Paris to Chicago in the US declared the alert the north west of Scotland at around 1.15pm today. The airliner is currently flying over the north west of England as it heads to Manchester Airport.
Airinfouk said the divertion was due to a "medical emergency" on board the flight. However, the reason was later given as a "technical issue".
Radars show the aircraft making a u-turn and the flight's path heading back across Britain.
Reports from various Twitter accounts suggested the plane was heading to London Heathrow.
However, Airlive said the flight was instead diverting to Manchester Airport