A Virgin Atlantic passenger plane has landed safely at London's Gatwick Airport after discovering a problem with part of its main landing gear.
Virgin flight VS43 with 447 passengers and 15 crew was travelling from Gatwick to Las Vegas when it had to return.
The Boeing 747 circled over southern England for several hours dumping fuel before making a bumpy but safe landing just before 16:00 GMT.
Gatwick's runway reopened at 19:03 GMT after being closed by the emergency.
Budget airline Easyjet said 12 of its flights due to land at Gatwick on Monday had been diverted and 32 due to depart from the airport had been cancelled.
In a statement, Gatwick Airport said: "The airport is now facilitating inbound and outbound flights but it will take some time for normal service to resume.
"We advise passengers to check with their airlines on the status of their flight. Updates will also be posted on the Gatwick website and on Twitter."
The statement said the airport was working with its airline partners to provide food, drink and welfare facilities to those affected by the delays and cancellations and volunteers were helping provide advice.
Arriving flights had been diverted to other London airports, while departing aircraft were severely delayed while the Virgin jet was being assessed on the runway.
The 13-year-old aircraft had left Gatwick for the US at 11:30 GMT on Monday.
After detecting the problem, the aircraft needed to fly holding patterns over Devon and then Sussex to dump fuel in order to be light enough to land.
Before the successful conclusion to the incident, Virgin announced the plane would be carrying out a "non-standard landing procedure" at Gatwick airport.
Pictures posted on Twitter of the aircraft circling over East and West Sussex showed part of the main landing gear had not fully extended.
Eyewitnesses reported the jet was flying at relatively low altitude and the pilot appeared to be trying to "shake" the landing gear down.
Nick Hughes, who was on board, said the crew made several attempts to try to free the landing gear.
"They put the thrust on quite heavily and then dipped down, I think, to try and loosen the gears but obviously nothing kind of worked.
"They gave it every opportunity before they tried the emergency landing. All credit due to the crew and the staff and of course the pilots because the landing was probably one of the softest landings I've ever had."
Another passenger, Hardeek Desai, said: "The staff were trying to keep everyone calm but a few passengers were a bit panicky. One of the crew came out to the seating area to reassure everyone everything was going to be OK.
"The staff were giving out thing like drinks and water to everyone to make sure everyone's OK. Generally, the mood was pretty good at this point until we hit the brace position."
Describing the mood on the plane as it was circling, passenger Dan Crane, 24, from Bromsgrove, Worcestershire, said it was "anxious, a lot were worried, some crying. The mood was quiet, just waiting for the captain's next announcement."
Mr Crane, who is with family and friends, said the crew kept everyone informed, adding: "They said it was an emergency landing and we had to brace on impact."
Sunjay Patel told the BBC: "It's been a rollercoaster. Yesterday I found out that I was going to Vegas for my 30th birthday, and not going to Vegas today it's been quite a crazy 24 hours. I can't wait to get to Vegas to enjoy it now."
He said the passengers had been taken to a hotel but they did not know when there would be a replacement flight.
Another passenger, Mike Kaufman, said: "This was one of the greatest emergency landings in history. It was very smooth."
He praised the pilots and the cabin crew, saying the landing had been "textbook".
Virgin Atlantic chief executive Craig Kreeger said: "I am very pleased to confirm that all customers and crew have now disembarked the VS43 flight to Las Vegas, which returned to Gatwick airport this afternoon following a problem with one of the landing gear.
"I understand that this will have been a very upsetting situation for the customers involved, and for their friends and family, and will have significantly disrupted people's holiday plans.
"We will make sure they are well looked after this evening, and will be operating a special flight tomorrow for everyone who would like to continue their journey."
Virgin Atlantic president Sir Richard Branson tweeted: "Well done @VirginAtlantic pilots & team for safe & skilful landing of #VS43. Thoughts with passengers & crew, thanks for support & patience."
A spokesman for British pilots' organisation Balpa said: "Pilots train hard for exactly this kind of situation. It goes to show that well-trained pilots are vital."