The UK government has said the air traffic control issue that led to widespread disruption to UK air travel was not caused by a cyber-attack.
More than a quarter of all UK flights were axed on Monday after a fault with National Air Traffic Services.
Delays and cancellations are continuing today, as passengers scramble to get on flights.
The PM’s official spokesperson said the incident will now be investigated by the Civil Aviation Authority.
They noted that the exact cause of the technical incident will be subject to investigation by the Civil Aviation Authority and then submitted to the government.
Earlier, Transport Secretary Mark Harper said it would take “some days to get completely everybody to where they should be”, after thousands of people were left stranded by the technical glitch.
He admitted the timing “was not at all helpful for people” – but that “those people in government who look at these things have looked at it and are clear that it wasn’t a cyber attack”.
Aviation data firm Cirium said that as of today, 5%, of UK departing flights had been cancelled as well as 5%, of arrivals.
Prime Minister Rishi Sunak said Mr Harper was in “constant dialogue” with all the industry participants and will be talking to airlines on Tuesday.
Heathrow Airport – the world’s busiest two-runway airport – said today that its schedule remained “significantly disrupted”, while EasyJet said some flights are still “unable to operate”.
National Air Traffic Services (Nats) confirmed the fault just after midday on Monday, before it announced that it had identified and remedied the issue.
But it said it would “take some time for flights to return to normal” – as it launched an investigation into what went wrong.
Passengers have recounted how they faced huge disruption as air traffic control had to input routes manually, rather than automatically, because of the fault.