Travel disruption could last for days after flights were cancelled leaving thousands of passengers stranded during a technical fault in the UK’s air traffic control (ATC) system.
Transport secretary Mark Harper said it was the worst incident of its kind in “nearly a decade” and announced an “independent review” will be carried out.
The issue started on Monday after a technical glitch meant flight plans had to be input manually by controllers.
The disruption continued into Tuesday with flights cancelled and delayed and many aircraft and crews out of position.
The UK’s transport secretary said: “This was a technical fault. We do not think this was a cybersecurity incident.
“And what will happen now with an incident of this magnitude is there will be an independent review.
“The Civil Aviation Authority will be putting together a report in the coming days, which obviously I will take a look at to see whether there are lessons to learn for the future, to see whether we can reduce the impact of this again.
“It’s nearly a decade since there was a significant issue like this.
“We want to make sure it doesn’t happen again, because of all the disruption that’s been caused to passengers across the country.”
Heathrow Airport said in a statement on Monday night: “We apologise for any inconvenience as a result of the Nats technical issues today.
“The issue has been resolved however schedules remain significantly disrupted.
“If you are travelling on 29th August, please ensure you contact your airline before travelling to the airport.”
By Monday afternoon, 232 flights departing UK airports had been cancelled, and 271 arriving flights were axed, according to aviation analytics company Cirium.
This equates to about 8% of all expected departures and 9% of expected arrivals, Cirium added.
National Air Traffic Services (Nats), the country’s leading provider of air traffic control, said at 3.15pm on Monday it had “identified and remedied” the technical issue affecting its systems and it was working with airlines and airports to support affected flights.
Juliet Kennedy, operations director at Nats, said the issue meant the automatic system that provides controllers with details of every aircraft and its route stopped working.
She added: “To manage safety, we had to limit the number of flights we could manage.”
Passengers stuck in the UK and abroad described their frustration, as some had no idea when or how they would get to their destination.
Rory Dollard, 40, cricket correspondent for the PA news agency, was stuck at Bergerac Dordogne Perigord airport in France and was told it may take up to six days before he and his family – his wife Joanne, 40, and children Emily, 10, and Arthur, eight – could return home to Skipton, North Yorkshire.
Lyudmila Hristova, 57, said her and her husband’s plans to attend her niece’s wedding in Bulgaria were “ruined” after BA cancelled their 2pm flight from Heathrow to Sofia.
And a German couple were considering returning home by train after their flight from London to Stuttgart was cancelled.
Myria Mebold, 36, also said that British Airways “didn’t know anything at all” when she and her husband asked about the situation and their flight.
Major UK airlines such as Tui and BA warned of “significant delays” for passengers amid changes to schedules.
Passengers were urged by airlines to check before they leave for the airport as their flight times may have changed.