A technical fault that engineers are still trying to “find and fix” has struck the UK’s air traffic control system, leaving thousands of people to face long delays in flights at the airports.

National Air Traffic Services stresses that UK airspace is not closed, but it has brought in traffic restrictions to “maintain safety” due to UK air traffic control system failure, reported BBC.

The company has not yet provided details on the cause or duration of the air traffic control fault. Airlines including Ryanair, EasyJet, Virgin, and Aer Lingus, as well as a number of UK airports, have issued delays and cancellation alerts.

No evidence of a hack, says a travel expert

According to Simon Calder, the travel correspondent for The Independent, such technological issues are “extremely rare” and only come up every five to ten years.

“There are of course back up systems upon back up systems which are designed to make sure that we shouldn’t have a shutdown like this,” he explained.

Calder pointed to online rumours suggesting that “some kind of hack” may be to blame for the technical problems, “I’ve got absolutely no evidence of that,” he noted.

“It may just simply be one of those system failures that we’ve seen in other parts of aviation – people will, of course, be reminded of the British Airways IT failures.”

Although airlines were not at fault in this instance, they nevertheless had to “deal with the consequences,” which might have cost them millions of pounds, Calder added.