Donald Trump’s administration on Sunday blamed the travel chaos stemming from Friday’s four-hour nationwide flight stoppage on prior presidents as well as a lack of congressional funding – though a Democratic senator argued that the Trump administration hasn’t properly invested all of the funds it has already been given to implement needed air travel infrastructure upgrades.

“I take responsibility for what was given to me by prior administrations,” the US transportation secretary, Sean Duffy, told CNN’s Dana Bash, a day after he said routine but necessary maintenance botched by a contractor had caused Friday’s Federal Aviation Administration (FAA) ground stop, leading to the delay or cancellation of thousands of flights.

Meanwhile, Democratic senator Chris Van Hollen of Maryland criticized how the Trump administration has managed existing funding allocated for the improvements coveted by Duffy.

“It’s really rich to hear the secretary pointing the fingers at Congress when Congress has given the administration what they asked for,” Van Hollen separately told CNN’s Bash on Sunday morning. “If they need more, they should come up and justify it. I will support what is necessary to have a safe system and a reliable system.”

Duffy claimed the congressional funding which Van Hollen mentioned – $12.5bn – was limited in scope and not nearly enough.

“I have no money in that $12.5bn that I can use for a new architecture for telecom,” said Duffy. “I can’t build new software to manage our airplanes in the airspace because it dates back to the 1990s, but there’s no money for that. There’s no money for towers. Our towers are old.”

Duffy also spent part of the interview with CNN defending Trump, who waited until Sunday to remark on the longest nationwide ground stop in 25 years.

The president’s comments came in the form of social media posts blaming the Biden administration and describing himself as busy “in the White House having meetings on many subjects”. They came after he had posted about what he envisioned to be a bipartisan congressional initiative to revitalize the motion picture and television industries.

“Before I even was sworn in, the president who loves the airspace was telling me we have to modernize,” Duffy said to Bash. “This is the first president we have who cares this much about modernizing the airspace.”

When asked why Trump took two days to comment on the ground stop, Duffy claimed he was in constant behind-the-scene contact with the president.

“He was fully engaged because this is important to him, and it’s important to America,” Duffy claimed. “The president is fully supportive, fully engaged, and was fully tracking what’s happening.”

In a post on Truth Social on Sunday, Trump blamed Joe Biden and demanded funding from Congress.

“The Biden Administration was an FAA disaster. Everything they touched turned bad,” Trump wrote. “We have the knowledge and plan for the Flight Control Systems, we need Congress to give the money, FAST!”

In another interview on Sunday on CBS News’ Face the Nation, Duffy told host Margaret Brennan that the FAA was currently investigating the root cause of the botched maintenance work that triggered the ground stop. He said the maintenance involved – replacing telecommunication lines from old copper wire to fiber optic cables – has occurred “thousands of times” without any issues.

The contractor, L3Harris, is reportedly conducting diagnostics testing. Duffy, as he has repeatedly done, said there continued being no indication of a foreign cyberattack. Professional Aviation Safety Specialists (Pass), the AFL-CIO labor union representing more than 11,000 workers at the FAA, said technicians it represents were not involved in the upgrades that led to the ground stop.

“The issue was isolated to two contractor owned and maintained routers that were being updated midday,” the union said in a statement. “Historically, contractors have followed a protocol where FAA employees conduct a risk assessment and coordinate the maintenance of the system or equipment.”

But the union said Pass-represented technicians were not involved in the upgrades at the center of Friday’s ground stop.

Duffy told Brennan in response to the union’s statement that “this was done appropriately, which by the way, it’s been done thousands of times by us, by others, by other companies”.

“This has never happened,” Duffy argued. “That’s why when you have a remote location like this, we felt comfortable doing it in the middle of the day because it’s been done thousands of times. We’ve never had this situation. We’re going to have to re-evaluate when we do this work.”

When asked if a risk assessment was conducted, Duffy did not directly answer. He said: “We do risk assessments on everything.”

Duffy also cited a Government Accountability Office report published in September 2026 that noted the need to modernize air traffic control systems.

He was asked about the report noting that “it could be prioritizing speed over costs and air traffic disruptions” in implementing a modernization effort of air traffic control systems. Duffy claimed, “In regard to speed, we are going, I think … at that the right speed.”

Pass has also called for progress on improving staffing of certified professional technicians at the FAA – and for the union to be fully engaged in efforts to implement what has been dubbed the Brand New Air Traffic Control System.

“These employees should receive training on new equipment and could ensure more robust installation and optimization – if the workforce were properly staffed,” the union added.