UK transport networks have been thrown into chaos by the global IT outage.
There are long queues at airports, while trains are also disrupted because of the problem.
Consumer group Which? advised passengers to avoid checking in luggage if possible.
Microsoft is currently experiencing a global outage which is impacting select systems at Heathrow. Flights are operational and we are implementing contingency plans to minimise any impact on journeys. Please check with your airline for the latest flight information. pic.twitter.com/s6Psd6pHUB
— Heathrow Airport (@HeathrowAirport) July 19, 2024
A spokesperson for Heathrow, the UK’s busiest airport, said the outage was “impacting select systems”.
She went on: “Flights are operational and we are implementing contingency plans to minimise any impact on journeys.”
Long queues formed at airports such as Gatwick, Luton and Edinburgh.
Ryanair advised passengers to arrive at airports early as it switched to manual check-in.
A traveller at Gatwick Airport said he had been queuing for more than three-and-a-half hours ahead of a flight to Miami, Florida.
Dean Seddon, 42, from Plymouth, told the PA news agency: “There are just people everywhere, there must be 400 people in this queue for the check in desk I’m at… it’s just bedlam.
“It’s one of those things where you kind of know we’re not going to fly, but you don’t want to leave because you don’t know.
“(Staff are) doing the best they can but they don’t actually know when it’s going to be fixed, so it is frustrating, but you kind of feel for the staff as well.”
Mr Seddon said there had been some people getting “agitated” in the queue but overall travellers had remained calm.
Rory Boland, editor of magazine Which? Travel, said passengers due to travel today “will naturally be deeply concerned”.
He went on: “If you can, avoid checking in a bag as queues for check-in at the airport will be long and IT failures typically lead to lots of lost bags.
“If you do check-in bags, make sure you keep medication, keys and any other essentials in your hand luggage.
“As these are extraordinary circumstances, compensation will not be payable for delayed or cancelled flights, but airlines nonetheless have a duty to look after you, including providing meals and accommodation if it becomes necessary.
“They should also reroute you as quickly as possible, though given the global nature of the problem, this may not be immediately possible.”
UK air traffic control provider Nats said its systems are “operating normally”.
Friday is one of the busiest days of the year for UK air travel, with many families embarking on summer holidays.
We are affected by the global Microsoft issues, so passengers may experience some delays while checking in and passing through security.
— London Gatwick LGW (@Gatwick_Airport) July 19, 2024
Passengers should still arrive for their normal check-in time. We apologise for any inconvenience and are working to resolve the issue as… pic.twitter.com/T9adpYELxW
Several US carriers have grounded flights, including United, American Airlines and Delta.
Train service information website National Rail Enquiries warned passengers there are “widespread IT issues across the entire network”.
Among the operators affected are Avanti West Coast, Great Western Railway, Southern and Thameslink.
National Rail Enquiries said: “Some train operators are unable to access driver diagrams at certain locations, leading to potential short-notice train cancellations.
“Additionally, other key systems, including real-time customer information platforms, are also affected.”
South Western Railway said all its ticket vending machines had stopped working due to IT issues.
It advised passengers to “purchase your ticket online, on the train or speak to a member of station staff”.
