Significant technical issues have forced British Airways to cancel a number of flights.
The passengers were stuck at the airport for hours.
Customers were unable to book flights or check-in online for several hours on Friday due to the website and app being unavailable.
British Airways apologized to customers for what it said was a very difficult week.
The system issues are not the result of a cyber attack.
The airline said travellers could still check-in at the airport, but services would be less than usual.
The airline said that they have back-up plans in place so that customers can still check-in at the airport.
We will make decisions about our operation tomorrow and notify affected customers of any changes.
Last week, BA apologized for letting people down after storms caused delays to unloading and loading luggage.
Ed Hall, a television executive from Woodstock, said he was stuck on a plane for more than an hour after landing.
He told the PA News agency that the crew couldn't access any IT systems to get a stand for passengers to disembark.
There were issues before his flight took off.
The pilot's system that calculates weight, loads and distribution went offline and we had to go back to the gate to get a manual copy from London.
The paper is running tonight.
luggage was piling up from passengers stuck on other flights after Mr Hall made it off the plane.
Sophia Prout, 33, from London, was waiting at the airport for her flight to Lisbon, which was canceled just after 2 pm.
She told PA News that she had been waiting for a total of four hours because she couldn't check in online.
She said that they were lucky that they could turn around and go home if the flight was canceled.