It hasn’t been a good year for federal aviation safety workers. January saw the worst US commercial airline disaster in decades, quickly followed by sudden layoffs, staffing shortfalls, major technology glitches at one of the nation’s busiest airports, and short timelines to rebuild the systems that govern national airspace. It somehow got worse this month, when a stalemate between congressional Republicans and Democrats led to a government shutdown.

Now, even employees deemed “essential”—including air traffic controllers and transportation security officials (also known as TSA agents)—are working without pay, balancing their usual daily stress with new chaos stemming from the government shutdown.

One Federal Aviation Administration engineer who works on air traffic systems says the shutdown has left them overwhelmed and worried about their colleagues. The employee doesn’t believe the system is less safe or less reliable but says it makes their office’s work less efficient and might slow down repairs. “One person can only answer, troubleshoot, and resolve so many problems at once,” the employee says. Prior to the shutdown, the FAA announced plans to furlough some 11,300 workers, who help maintain airspace design, infrastructure, and technology.

Longtime air safety workers describe this month’s shutdown and funding lapse—the fourth in the past two decades—as familiar, but more unsettling than shutdowns past. There’s the usual anxiety of missing paychecks, which will hit some employees as early as this weekend, and others mid-next week. “They don’t take IOUs at grocery stores, gas stations, day cares,” says Johnny Jones, the president of the American Federation of Government Employees Local 1040 and a transportation security officer with the Transportation Security Administration at Dallas Fort Worth International Airport. “There’s definitely a different tone in the workforce. People are confused and concerned.”

Employees working through the shutdown are already doing without the support of their furloughed colleagues; some projects have simply stopped. Air safety workers are afraid that the situation could get even worse, and the contractors who support vital functions could still be furloughed. “We feel undervalued and unappreciated as we work to keep the National Airspace System safe,” says one employee of the Air Traffic Organization, the FAA’s operational arm that includes Air Traffic Control, who has so far been classified as essential but fears they may be furloughed soon.

Federal employees told WIRED they were confident they could keep air travel safe through any government funding lapse. But the strain will build as the shutdown drags on—meaning more delays and cancellations, says Michael McCormick, who manages the Air Traffic Management program at Embry-Riddle Aeronautical University and worked at the FAA for three decades. The situation will be especially tricky for air traffic controllers, who have been dealing with staff shortages for years. (Unlike in shutdowns past, the academy that trains new controllers has remained open.) “Controllers make thousands of decisions every day,” says McCormick. “There are thousands of lives at stake, and they’re well aware that they need to be at the peak of their game. So if they’re ill, if they haven’t slept, if they’re not mentally capable of working in traffic, they know they shouldn’t be.”

Workers are also concerned that the White House and federal officials will follow through with their threats to use the shutdown as an excuse to execute mass firings and will continue to push partisan talking points that won’t move politicians closer to a deal. (The US Department of Transportation, along with a number of other agencies, has referred to the “Democrat-led shutdown” in public and internal communications.)

“It feels as if they want us to be afraid, but I’m just angry,” says the FAA employee. “Angry that they’re using us as hostages. Angry at their repeated lying, hypocrisy, and performative partisan drivel in my work inbox.” Just before the shutdown began, they note, they renewed their Hatch Act training. The Hatch Act protects government employees from political coercion and sets limits on the kinds of political activities they can partake in. “I don’t have a good word to describe this state—some mix of disbelief and dystopia,” says the worker.

“We will never compromise on safety. When staffing constraints arise, the FAA will slow down air traffic at impacted airports to ensure operations remain safe,” FAA spokesperson Hannah Walden tells WIRED, adding that Transportation secretary Sean Duffy “said that air traffic controllers who report to work will be paid. Regarding reductions in force (RIFs), DOT has been clear for months: safety critical positions—including air traffic controllers—have and will continue to be exempt from any RIFs.”

In a written statement, a spokesperson for the TSA said of employees working without pay: “It’s unfortunate they have been put in this position due to political gamesmanship. Our hope is that Democrats will soon recognize the importance of opening the government.”

On Thursday, Duffy suggested on Fox Business News that controllers and other workers who don’t come to work during the shutdown would be fired. “If we have a continual small subset of controllers that don’t show up to work, and they’re the problem children … if we have some on our staff that aren’t dedicated like we need, we’re going to let them go,” said Duffy.

One air traffic controller described this week’s working conditions as “pretty much the same” but with “an undercurrent of fear that the dipshits in charge will use this as an excuse to decertify our union and take away all bargaining rights.”

Air traffic workers know that accusations of coordinated activity and sick-outs, or informal labor actions that could violate long-standing bargaining agreements with the government, are especially perilous right now, as federal officials threaten the status of public sector unions. The Trump administration suddenly ended TSA workers’ collective bargaining agreement in March, before a court preliminarily halted the move in June. Workers worry that taking an absence, even when it’s needed, could have long-term consequences for their union—and therefore, their working conditions.

The National Air Traffic Controllers Association did not respond to WIRED’s request for comment. But a pop-up on the public union’s website notes that it “does not endorse, support, or condone any federal employees participating in or endorsing a coordinated activity that negatively affects the capacity” of the National Airspace System.

Jones, the TSA agent and union leader, says his group won’t organize sick-outs. But employees may have to call out if the lack of pay means “they don’t have the means to commute into work,” he says.

“We are sick and tired of being political pawns for Washington,” adds Jones.