Passengers on-board a United Airlines flight from Heathrow to New York have revealed why the jet liner circled the skies above Lancashire last night.
Flight UA921 departed Heathrow at 6.27pm yesterday (December 11) destined for New York, but a 'mechanical issue' forced the plane to return to London.
Before returning to Heathrow, the Boeing 767 was forced to circle the Fylde coast for more than two hours in order to burn fuel and ensure a safe landing.
Flight radar data showed the aircraft turn back just west of Glasgow, before circling the Fylde coast at 21,000ft, between Fleetwood and Southport.
The plane landed back at Heathrow at around 9.50pm after circling through the sky above Lancashire for more than two hours.
The airline, the third largest in the world, said the jet was in need of "maintenance work" and a decision was made to ground the plane for 24 hours.
It has declined to comment further on the exact nature of the 'mechanical issue'.
But a couple of emergency service workers on-board the flight have now revealed what happened.
Ross and Rhia Ludford, from Leicester, both work as paramedics for East Midlands Ambulance Service.
Mr Ludford said he and his 7-months pregnant wife - and more than 200 other passengers - were left 'frantic' after the pilot reported a problem with the plane.
"We were not informed of any issues prior to the flight, but as we flew over Glasgow we were told that there had been a vibration coming from the front of the plane", said Mr Ludford.
"The flight deck announced that the pilot had detected a problem and he thought it was unsafe to continue the journey across the Atlantic.
"We were aware that we were circling the Lancashire coast as we were told we needed to use fuel prior to landing, but we weren't sure whether it would be Manchester or Heathrow.
"People were beginning to get a bit frantic after the pilot mentioned a problem with the plane.
"My wife is heavily pregnant and it was difficult to gain any information on what was happening until we were back at Heathrow at around 10pm."
After touching down at Heathrow, passengers and crew were unable to leave the plane for a further two hours.
"Even after we landed, we were not allowed off the plane until 11.45pm whilst they checked the plane.
"They informed us that it was taking the engineers too long to look at the issue on the runway, so we are still unsure of what the fault was or whether it was safe or not.
"But it was clear that it wasn't safe for us to continue to New York that night."
Ross and Rhia said they have been left "exhausted and worried" by the incident, despite being experienced flyers.
"We have both been on a lot of flights but this is the first time anything like this has happened to either of us.
"It was an exhausting and worrying experience, but it wouldn’t stop us flying again."
The couple, who are expecting their first child, said they had been looking forward to a short Christmas break in the Big Apple before becoming first-time parents in March.
"We have been offered no information regarding compensation and have been put up in a hotel with a further flight booked for later today.
"It's a real shame because we are missing out on a full day of our mini holiday.
"It was only supposed to be a short week away for us before the baby is born.
"We both work for the NHS as ambulance workers and we hardly get a day off, let alone five days to enjoy a holiday together.
"We were hoping to travel today instead, but most of the morning and afternoon flights are already fully booked.
"We finally managed to find a flight, but sat apart, so not ideal with a 27-week pregnant wife."
United Airlines said the 375-capacity passenger jet will return to service at 10pm tonight, when it is scheduled to depart Heathrow for New York.
A UA spokesman said: "Our team at London Heathrow Airport provided assistance to customers of United flight 921 (London Heathrow Airport – Newark Liberty International Airport), which returned to London Heathrow yesterday to address a mechanical issue and was subsequently cancelled.
"The aircraft landed safely and customers deplaned normally.
"We made arrangements for our customers to complete their journeys as soon as possible and provided meal vouchers and hotel accommodation.
"The aircraft is scheduled to depart London Heathrow Airport today at 10pm (local time) and will operate as United flight 2818.
"We apologise to our customers for the inconvenience caused."
The Gazette asked Manchester Airport whether it had been made aware of the incident and whether it had been placed on standby for an unscheduled landing.
The airport said it was unable to comment on the incident.
NAT (North Atlantic Operations), which manages the airspace between Europe and North America, also declined to comment.
"As this is a matter for the airline, we will not be providing comment", said a NAT spokesman.
The Civil Aviation Authority, which oversees and regulates all aspects of civil aviation in the UK, has been approached for comment.