According to the Flight Radar website, the UA921 flight departed Heathrow at 6.27pm and was meant to be heading to New York.
Flight radar data showed the Boeing 767 turn back just west of Glasgow before flying at 21,000 feet above Lancashire time and time again - reportedly for more than two hours.
There was definitely an aircraft circling above Blackpool and Lancashire, however, and a number of messages queried the airline's initial response.
And after being asked again what's happening, United Airlines said: "We have been notified that the plane needs to have maintenance work done to it. The current plan is to return it to London Heathrow Airport."
A spokeswoman for Lancashire Police said she was not aware of any ongoing incidents, while the pilot did not need to declare an emergency, it is understood.
The flight appeared to be heading back to Heathrow at around 9.15pm after, it is thought, dumping fuel to ensure a safe landing.
The plane landed at around 9.50pm.
United Airlines told The Gazette in a statement: "The aircraft had a mechanical issue and it’s returned to Heathrow.
"We are making arrangements to get our customers to their destinations."