The shutdown of the federal government has begun to palpably affect the country’s airports, including at Denver International Airport, which is seeing staffing shortages, according to officials.

By Monday evening, the Federal Aviation Administration was reporting that staffing shortages were creating delays at DIA, as well as airports in California and New Jersey.

Denver International Airport officials anticipate that more than 938,000 passengers will travel through airport checkpoints between Oct. 9 and Oct. 20, a 5.5% increase over the same time period in 2024.

Lawmakers, meanwhile, continue to disagree on funding the federal government, forcing air traffic controllers and other essential federal employees to work without pay.

More than 13,000 air traffic controllers are expected to continue working during the shutdown, according to U.S. Department of Transportation documents, and they are set to miss their first paycheck on Oct. 14.

In the meantime, some air traffic controllers have been calling in sick.

At a news conference on Monday in Newark, New Jersey, U.S. Department of Transportation Secretary Sean Duffy confirmed the FAA is already seeing “a slight uptick” in controllers calling out sick since the federal shutdown began on Oct. 1.

Whenever the situation worsens and creates a shortage of controllers, the FAA restricts the number of takeoffs and landings to ensure controllers aren’t overwhelmed and the system remains safe. 

“Our priorities are safety, and so if we have additional sick calls, we will reduce the flow consistent with a rate that’s safe for the American people,” Duffy said. 

This creates delays and, in some cases, cancellations. 

⚠️ Ground Delay Program at Denver International Airport (DEN) due to STAFFING / STAFFING. This is causing some arriving flights to be delayed an average of 39 minutes..#DEN #FAA #AirportDelays

[2025-10-06 18:45 UTC]

— Air Traffic Control Alerts (@ATCAlerts) October 6, 2025

The worst problems occurred in Burbank, where California Gov. Gavin Newsom said that no controllers were on duty during the evening, resulting in flight delays of two and a half hours at that airport.

On Monday, FlightAware, a popular flight tracking app, reported that more than 4,000 flights in U.S. airspace were delayed, including 29% of arriving flights at Denver. In some cases, the weather and airport surface construction may have also contributed to the flight delays.

Denver airport officials said they recommend that passengers check with their airlines for updates and arrive at the airport at least two hours before their scheduled boarding time.

The Transportation Department has been able to keep the Air Traffic Controller Academy in Oklahoma City open for now with funding from previous years. But Duffy said he is still concerned about the potential impact on efforts to hire and train new controllers to solve a longstanding shortage. 

Duffy said the support staff who train controllers after they graduate from the academy could be laid off.

Union extends a firm warning

Union officials have warned air traffic controllers that organized “sickouts” will not be tolerated. 

Sickouts are not official union actions, but rather the actions of individual controllers taking sick days.

“We must be clear, NATCA does not condone any coordinated activity that disrupts the National Airspace System or damages our reputation,” National Air Traffic Controllers Association Vice President Mick Devine said. “Such actions are illegal, risk your careers and destroy our ability to effectively advocate for you and your families.”

A statement on the NATCA website added a warning, stating that participating in such activities is not only illegal but also “could result in removal from federal service.”

Airline vows to keep servicing rural Colorado

While larger airports will likely suffer delays as long as the shutdown lingers, money from a program that is helping smaller airports in Colorado and elsewhere will run out on Sunday.

The Essential Air Service (EAS) program is a federal initiative that subsidizes airline service to smaller, rural communities, ensuring access to the national transportation network and vital services, such as medical care and economic opportunities.

“That money runs out this Sunday,” Duffy said. “So, there’s many small communities across the country that will now no longer have the resources to make sure they have air service in their community.” 

U.S. DOT documents said three airports in Colorado receive EAS funding and use Denver-based Denver Air Connection to provide services: 

• San Luis Valley Regional Airport in Alamosa
• Cortez Municipal Airport in Cortez
• Pueblo Memorial Airport in Pueblo

The subsidies incentivize airline carriers to operate routes that are not economically viable for airlines to fly on their own.

A Denver Air Connection spokesperson said the company plans to continue normal operations at all of its EAS stations, nationwide, “even if appropriated funding runs out.”

“Denver Air Connection wishes to assure all our partner communities and guests that we have no intention of suspending service or cancelling flights,” stated Jon Coleman, the airline’s senior vice president for strategy and business development. “We understand how important these flights are for our passengers. For the foreseeable future, all DAC flights will operate as scheduled.”

Gred Pedroza, Pueblo Memorial Airport director of aviation, lauded Denver Air Connection for its commitment to continue its service, keeping residents and travelers connected to Denver International Airport.

“Denver Air Connection will still fly according to their press release, and they will do so at risk, which means, you know, they’re going to be doing it without the added subsidy,” Pedroza told The Denver Gazette on Tuesday.

Pedroza added that Transportation Security Administration agents, as well as the airport’s air traffic controllers, must report to work amid the shutdown.

Duffy said that the long-standing EAS program enjoys bipartisan support and is “an important program, but we don’t have the money for that moving forward.” 

The Associated Press contributed to this story.