Passengers flying to and from Britain's airports are warned they are likely to face disruption after rare nationwide ground stop was issued in US

Thousands of passengers flying to and from UK airports faced major disruptions and travel chaos after a rare nationwide ground stop was issued in the US.The US's Federal Aviation Administration (FAA) had halted all flights nationwide 'due to extraordinary circumstances and for reasons of safety'.Now US aviation regulators have lifted the ground stop of all flights across the country after several hours down on Friday following the major communications outage. It is unclear what the knock on effect will be for UK passengers travelling today.Just minutes after the announcement, the impact hit Britain's biggest airport, where Heathrow was last night a scene of 'real confusion'.At around 11pm, a flight which had been due to leave for New York from Heathrow returned to the airport after a medical emergency in the air.British Airways flight BA-113 departed Heathrow at 5pm and was routing to JFK Airport in New York at the time. There were 171 passengers and crew reportedly on board.One passenger, who gave his name as Richard, said: 'We were on the flight to New York and we were told there was a medical emergency. They stopped in Shannon. It was complete confusion. Then news started to come in about the flights in America being grounded. Moment British Airways flight suffers double tail strike in aborted landing at Heathrow AirportThe Federal Aviation Administration (FAA) halted flight departures across the US following a major communications failure. Above is Baltimore/Washington International Thurgood Marshall Airport (BWI) Flyers were seen waiting at New York's JFK International Airport during the nationwide ground 'I saw a notification on Bloomberg about the situation in the US, and I showed it to the flight attendant. She hadn't heard anything about it.'Originally, we thought we were staying in Ireland. Then they said we're coming back to Britain. Now we're in Britain, we don't know how we will get back.'Another passenger said: 'I need to go back to America urgently. That's why I got the flight on a Friday evening. It's madness.'Now I have no idea how I will get back. It's going to be carnage. It's real confusion.'Responding to customers on X, British Airways apologised for delays to its flights, and recommended passengers travel to the airport as planned to arrive for the original departure time.It told one X user that it will operate flights due to take off tomorrow, but added it is monitoring the situation and 'can't guarantee that this won't change'.It is understood the situation had minimal impact on London Gatwick Airport.The FAA previously said: 'There has been a temporary telecommunications outage - out of an abundance of caution, all flights have been halted. Every flight has been accounted for, and international flights will be handled on a case-by-case basis.' It added that it gave airlines up to four hours to file flight plans because of the communications failure affecting air traffic control centres.More than 15,000 flights were delayed and another 1,700 were cancelled as of Friday 6pm, according to FlightAware, a flight-tracking service.In the UK, more than 4,000 had been cancelled or were classified as 'no-fly' according to Cirium. Air traffic control radar systems and radio frequencies went down simultaneously in multiple locations across the country, an aviation source familiar with the situation told CNN.Controllers remain in the dark about what caused the failures and the full extent of the disruption, the source added.Another airline source told CNN that the FAA 'doesn't know yet what is going on. It is affecting different facilities in different ways.'Ten minutes ago, they were on a crisis call, and there was still no clear answer as to the cause.' Three US-bound flights scheduled to leave on Saturday morning – all operated by Virgin Atlantic – would have been affected had the issue not been resolved.A Virgin Atlantic spokesman said: 'We're aware of the ground stop order issued by the Federal Aviation Administration for all US airports.'We're closely monitoring the situation and assessing any impact to our flights. We advise any customers due to travel to check their flight status at virginatlantic.com.'The FAA has ordered all departing traffic in the US to remain on the ground until further noticeA British Airways spokesman said: 'Our flights departing the United States may be delayed due to the ongoing air traffic control issue.'Customers are advised to travel to the airport as planned so we can try to depart our aircraft as quickly as possible.'This is entirely outside of our control and our teams are working hard to minimise any disruption to our customers.'A spokesman for Aer Lingus said its flights arriving into the US are able to land, and some of its flights departing from the US are being cleared to depart.The spokesman added: 'We are continuing to monitor the situation closely and will communicate directly with customers who are impacted by the disruption.'Customers should continue to check aerlingus.com for the latest updates.'One possible cause for the massive ground stop reportedly being investigated is a software update gone wrong, leading to the systems outage, according to Bloomberg. Department of Homeland Security Secretary Markwayne Mullin also said there were no signs of foul play. US homeland security secretary Markwayne Mullin said: 'There is no reason for the public to be afraid or scared for your loved ones. This isn't another 9/11… This is a telecommunications outage.'Throughout FAA, out of abundant of caution, we have grounded all the flights, and all the flights are accounted for.'As incoming flights, either internationally or the flights that are currently still in the air, we'll be dealing with those case by case.'As you can imagine, there will be a priority list as they start coming in.'Mr Mullin added: 'Everybody is safe. There is no reason to be concerned about your loved ones if they're flying or anything like that. I just want to make sure everybody's at ease about that.'He went on: 'There is no indication as of yet that this was a nefarious attack against us. It's just a telecommunication outage as of right now.'Mr Mullin has acknowledged it is 'a crisis'.He said: 'Every agency that has an asset that is involved in this… we're all working together. But that's what we do, right?'I don't want to get to say that this is a crisis but it is because we had to do a nationwide ground stoppage.'But Mr Mullin added: 'It's what the government works well at. That's what we're here for, and so we are well positioned and communicating very well.'The president took a lead in this immediately, and he gave us the assets and the communication to move forward in a fast way.'Mr Mullin warned it will take 'some time' to resolve the issue, adding people should not expect things to be 'turned around within the hour'.'This is going to take some time, but once again, everybody is safe. The flights are accounted for, and there should be no fear to the public at all.'A spokesman for American Airlines said: 'The FAA has temporarily paused departures nationwide.'Flights already in the air can continue to their destinations.'We expect disruption to our schedule for the rest of the day, depending on the length of the FAA's nationwide ground stop.'It will be all hands-on deck across American to get customers on their way as soon as possible when the FAA lifts this ground stop.