British Airways has cancelled all short-haul flights from Heathrow until midday today because of what they call ongoing technical issues.
Last night, passengers first reported having problems as BA suffers another big outage, causing the website and app to fail and flights to be grounded.
The company said the issues, which may also cause delays for its customers using Gatwick and London City Airport, is related to a hardware issue and is not because of a cyber attack.
The major outage has caused cancellations and delays of flights, pile-ups of luggage and passengers stuck on planes after landing at Heathrow.
It said long-haul flights are still operating, but customers may experience some delays.
Now, they say they won't be flying short-haul until this afternoon.
In a statement, the airline said: "We are extremely sorry that due to the continuing technical issues we are facing we have regrettably had to cancel all short-haul flights from Heathrow today until midday.
"Customers due to travel later today should check their flight status on ba.com before coming to the airport as we anticipate further disruption during the day.
"Our long-haul services at Heathrow and all flights at Gatwick and London City Airport are due to operate as planned, but customers may experience some delays.
"Our website ba.com is working and customers can check-in online and at the airport.
"We are offering customers on cancelled services options including a full refund and all customers booked to travel on short-haul services from Heathrow today can opt to rebook to a later date for free if they choose. We will be contacting customers proactively.
"Our teams have been working hard through the night and will continue to do so to resolve the issue as soon as possible. We advise our customers due to travel today to check ba.com for the latest flight information before coming to the airport.
"We know we have let our customers down and we will do everything we can to make this up to them - but for now our focus is on getting as many customers and flights away as we can."
British Airways has been told it needs to be transparent about what is causing the technical problems that are resulting in flight cancellations, a travel expert has said.
Paul Charles, chief executive of travel consultancy The PC Agency, said: "Ongoing technical issues don't fill consumers with much confidence.
"Many people have saved up during lockdown to get away at the first opportunity and some are now finding that computers, not Covid, are preventing their getaway.
"BA needs to be transparent on what's causing these issues and how soon they will be fixed."
Heathrow Airport, meanwhile, said on Friday: “Heathrow's systems are operating as normal.
"We are aware of a technical issue that British Airways are investigating and we will be working with them to provide updates to passengers as soon as they are available.”
Last night, angry travellers took to twitter demanding to know what was going on.
One user posted: "Am at Heathrow. British Airways flights all grounded as the computers have piled in. BA’s screens have gone off but the main ones in the hall are still on. BA staff seem very chilled, no flapping."
Another said: "[Second] time in a week I’m sat on a plane going nowhere. This time an IT issue. No information coming out, no provisions on board. Not good enough."
A third posted at 8pm: "In T5 at LHR, all British Airways systems have been down for over an hour, all flights are grounded."
