Air traffic in US expected to return to normal

US air travel is expected to largely return to normal by Sunday night following a massive nationwide ground stop that disrupted thousands of flights

and marked the country's longest flight shutdown in 25 years.

Authorities identify an upgrade of copper wires in the antiquated air traffic control system as the culprit of the large-scale disruption.

Passengers sleeping at New Jersey's Newark Liberty International Airport Saturday, after a weekend of flight delays and cancellations stranding hundreds of thousands.

Passenger from New Jersey Caroline Ruiz said "I've been here since 3pm yesterday and I honestly don't know what time it is now. I was flying to Vancouver, but it seems like now I'm flying to LA.

And I have about 24 hours of flights to come next to me because I'm going to Australia, which is my final location."

Passenger from New Jersey Chuck Amasio "Well, got to the airport yesterday on time, we are still waiting for our flight."

New technology being added to the nation's air traffic control system overloaded antiquated equipment and caused intermittent communications

and radar gaps, leading to the flight shutdown of more than four hours, Trump administration officials said.

Airports were slowly returning to normal by Sunday Secretary of Transportation Sean Duffy said as he explained what actually happened.

US Secretary of Transportation Sean Duffy said "So, here's what we believe happened yesterday. In at least one of our remote FAA locations, a contractor was doing routine maintenance

to switch telecommunication lines from old copper wire, and they were bringing it over to fibre. Now, the work happening was due to the age of the copper wire that we were replacing.

It was such an old wire that it was being discontinued. Meaning that line was going to get shut down. So, we had to switch it over from old copper. We had to bring it over to fibre, going from TDM to IP

or from analog to digital. Either through contractor error or a faulty piece of equipment, that router that was being replaced as we switched from copper to fibre

it started flooding other routers and our air traffic control system."

Duffy added the effects of the flight stoppage could be felt for days