A passenger on board stated that right after takeoff “as the wheels were coming up, we heard an usual sort of noise which was followed by a really loud grinding noise. That persisted for a while and then one of the senior flight officers came over the tannoy and said there was a mechanical problem.”
The pilots on the United Airline flight UA-76 alerted air traffic control they were no longer sure the landing gear would come down when they landed. An emergency was immediately declared.
The flight took ff at 11:10am local time and did not land in Shannon until 2:30pm as it burned off fuel over the irish coast.
On board were the US soccer under 18 women's team and well known actress Geraldine Hughes who told the Irish Independent she has written a farewell note to her husband.
Hughes, who starred in "Rocky Balboa" and "Gran Torino" and several Broadway shows, said: "It was awful. It is amazing what this sort of situation does, because we knew for two hours that maybe the landing gear wasn't going to work and we kept hearing this noise.
"At a certain point I got through to texting, when we were at a lower altitude, and when my other half texted me, I lost it - I started to cry. The possibility was that we may not make it.
"I wrote him a goodbye note. I composed a goodbye note on the notes section of my iPhone.
"The thing about our life is, I always tell him what I am feeling. And I just thought, 'well I don't want to leave those things unsaid.' I didn't send it but I told him I wrote it and he said he doesn't ever want to read it."
Many passengers praised the cabin crew and pilots for the professional job they did and their ability to keep people calm on the flight. But some passengers were still highly agitated and worried. "At one point they said make sure your passports are in your pocket and we were thinking is that for ID purposes,” said Hughes
"But the crew were fantastic - I trusted every single one of them that they would take care of us. And it was the smoothest landing ever - it was crazy."
The flight made a low fly-past at Shannon so ground crew could evaluate the landing gear. Passengers were told to brace for a landing because even though the gear was down there were fears the gear could buckle on landing.
United Airlines Flight UA76 Belfast to New York about to make a low pass over Shannon to inspect landing gear before returning to Belfast pic.twitter.com/8AVDvXmW5t— Séamus Kearney (@SeamusjKearney) October 24, 2016
Paul Eurich, 47, a member of the US Army, was returning home after visiting his daughter in Belfast and was asked by the flight crew to man the emergency doors after landing.
He said: "I was just told about going through procedures of opening the door. I was to go down first and assist people off while another guy stayed up top.
"I was not very worried to be honest. The entire crew were very professional - calm, relaxed and they kept passengers informed and calm. I was happy to help."
The US under-18 women's national soccer team was also on the Boeing 757, returning home after competing in the Women's International Cup in Northern Ireland.
Press Association reporter Lesley Anne McKeown was on board the transatlantic United Airlines flight and she reported the following:
"We were heading to New York for three nights to celebrate my husband Brendan's 40th birthday. I am 29 weeks pregnant and had to get a letter from the doctor to say I was okay to fly.
"Everything was normal with the take-off, but shortly afterwards, as the wheels were coming up, we heard an usual sort of noise which was followed by a really loud grinding noise. That persisted for a while and then one of the senior flight officers came over the tannoy and said there was a mechanical problem.
"He said there was 'nothing to worry about...at this point.' When he said 'at this point' I got worried. He said we would hear this noise for the duration of the flight.
"Maybe 20 minutes later the captain came over the tannoy and said there was a problem with the landing gear and that we had turned south and we were heading to Shannon Airport and we were going to have to circle for two hours to burn off fuel because we were too heavy with fuel to land.
"I was concerned and quite worried. Brendan was reassuring me, saying 'There's nothing to worry about. It's fine.' But as time went on you could see the cabin crew speaking to various people. There was a US soldier behind us – they spoke to him and asked would he mind sitting at one of the emergency exits and help out in the case of an emergency evacuation.
"They were also briefing everyone sitting at emergency doors on what to do, how to get people out and down the slides. They were also speaking to a number of nurses and doctors who were on board.
"So the atmosphere was tense. People were just worried. They were trying to keep their spirits up, but you could see people were worried and scared. This lasted for two hours.
"We had to do a fly-past at Shannon Airport so they could see whether the front wheels were up or down. They confirmed the wheels were down. There was a palpable sense of relief, but they still didn't know whether they were in the lock position – whether they could take the impact of the landing.
"Then they had to turn off the cabin pressure – they told us that's why we could feel our ears popping. We came down to 3,000ft and then at 1,000ft they told us to adopt the brace position. Earlier they had showed us how to get into the position. So the cabin crew was shouting 'brace, brace' at us as we came in to land.
"But that's not when I was most frightened. I was most frightened earlier, when they were doing the fly-past. I was holding Brendan's hand and I was holding the hand of the woman beside me - I grabbed her hand. She was on her own so I thought I'll just hold her hand too, even though she was a former US Air Force doctor.
"There was huge relief when we landed. Some people were crying with relief. There was a massive round of applause for the captain and the crew, and they deserved it."