The ground stop was lifted after about four and a half hours, but the impacts continued over the weekend.On Saturday, airlines cancelled more than 5,900 flights and more than 7,000 others were delayed.Investigators are still working to determine the root cause and who is at fault, but Duffy said the administration decided to ground flights after failures in a key system that allows air traffic controllers and pilots to communicate. The transport secretary said a computer router installed as part of an upgrade from copper wire to fibre started sending out faulty signals.
He said on Sunday that the router - a piece of equipment which directs traffic across the network - was installed in El Dorado, Arkansas, and "flooded our network". Duffy said that issues will continue to arise until the US makes major modernising changes to its air control system.
The system needs a complete overhaul, he said."Let's not lie to each other," he said on NBC's Meet The Press. "We have to make investments into a network that has been neglected for decades."In a post on Truth Social on Sunday, Trump urged US lawmakers to allocate the money, saying "we can get it built quickly and efficiently"."It will be the BEST SYSTEM anywhere in the World. Much of our current air control system is 50 years old - RIDICULOUS!
We have already started the work, but it should be done all at once, not in drips and drabs," he said. Experts say the US uses antiquated technology for flight communications.
Aviation analyst Miles O'Brien described the US system as "a house that's about to be condemned".He told the BBC: "I think most of us could look at this and go 'this is a system in the United States that we have allowed to decay'. It is worse than a fixer-upper."