Telecommunications fault caused four-hour US flight stoppage, officials say

The US aviation authorities said a four-hour nationwide flight stoppage on Friday was caused by a problem during routine telecommunications maintenance, as airlines continued to deal with widespread disruption on Saturday. The stoppage delayed or canceled thousands of flights and was the longest nationwide grounding in 25 years, leaving passengers stranded and unsure when they could travel.

Transportation Secretary Sean Duffy said a contractor was switching lines at a remote FAA facility from copper wire to fibre optic cable; officials are investigating whether the fault involved user or installer error, or defective equipment. More than 4,000 US flights had been canceled by 11am ET on Saturday, following over 8,000 cancellations on Friday. The FAA said it expected further disruption on Saturday and hoped airlines would restore full schedules by Sunday; officials said they saw no evidence of a cyber-attack or AI involvement.