A serious computer glitch in the United Kingdom has caused massive flight delays around the country, stranding thousands of passengers.
The UK's National Air Traffic Service said that the computerized telephone system which is used to direct lights in British skies failed to change from nighttime to daytime mode.
The glitch had planes backed up in skies all over the UK, circling airports before being landed manually.
Planes leaving UK airports were also halted, waiting on runways, with major airports like Heathrow, Gatwick, Stansted, Cardiff and Glasgow, all affected.
Many airlines cancelled flights in the interim, while the problem is corrected.
The problem will not be fixed until later in the evening, say authorities.
Passengers were not the only ones frustrated by the news. Airlines called on the government to act faster.
"While we acknowledge problems can occur, where is the contingency? It's simply not good enough and the CAA [Civil Aviation Authority] needs to act now," said budget airline Ryanair in a statement.
BBC reported that by midday Saturday air traffic controllers at affected airports had only handled 2,800 flights out of the usual 3,500 for that period.
Safety was not affected by the glitch, according to officials.