On Sunday, Association of Flight Attendants (AFA) international president Sara Nelson all but called for a general strike to stop the government shutdown.

Speaking after receiving an award given in honor of Martin Luther King Jr, Nelson, who leads the 50,000-member union affiliated with the Communications Workers of America, said King “called on us to come together with the ‘fierce urgency of now’ to fight for justice …. There is a humanitarian crisis unfolding right now for our 800,000 federal sector sisters and brothers who are either locked out of work or forced to come to work without pay due to the government shutdown.”

After noting the shutdown had the potential to degrade her members’ safety and job security, Nelson said, “Almost a million workers are locked out or being forced to work without pay. Others are going to work when our workspace is increasingly unsafe. What is the Labor Movement waiting for? Go back with the Fierce Urgency of NOW to talk with your Locals and International unions about all workers joining together – To End this Shutdown with a General Strike.”

This isn’t blustery rhetoric. In fact, it wouldn’t even take a full general strike. If Nelson’s fellow flight attendants, or workers in a handful of other strategically important sectors, were to strike, they could force the government to reopen very quickly.

In the last few weeks, several writers have argued that as some of the most visible and most critical workers forced to work without pay, TSA workers have the power to end the shutdown with collective workplace action. But there’s no sign that will happen any time soon. Legal consequences for striking are significantly higher for federal workers than other workers. And TSA workers are among some of the lowest-paid in the country, meaning even though they aren’t currently getting paid, the risks of losing a steady job and the promise of back pay are even higher for them than other federal employees.

While TSA workers have been absent from work at higher rates than normal lately, so far there’s no evidence of coordinated action or political motivation. Rather, the cause seems to be low morale and the burdensome cost of commuting to the job.

TSA union officers have also downplayed the possibility of a strike. Cairo D’Almeida, president of the local union representing TSA workers in Seattle told the Seattle Times, “You’re not old enough to remember the air traffic controllers, and what happened to them,” referring to the catastrophic PATCO strike of 1981. “I know President Trump wouldn’t hesitate one second to get rid of the entire federal workforce …. It’s unfair this political burden has fallen to us.”

But there is another group of workers who also have the power to shut down the nation’s airways, who would face far fewer legal penalties for doing so: flight attendants like those Sara Nelson represents.

Along with TSA workers, air traffic controllers have been forced to work through the entire shutdown without pay. Government airplane inspectors were initially furloughed, but were called back to work unpaid about two weeks into the shutdown. Though these workers are highly skilled and doubtless dedicated, low morale and the stress of depleting bank accounts and unpaid bills will inevitably take a toll on their job performance.

In a joint press release, AFA and unions representing pilots and air traffic controllers said “we are not confident that system-wide analyses of safety reporting data, which is used to identify and implement corrective actions in order to reduce risks and prevent accidents is 100 percent operational due to reduced FAA resources.

In other words, pilots, air traffic controllers, and flight attendants think it is less safe to fly now than before the shutdown began.

If members of AFA or other private sector aviation unions collectively decided their planes were unsafe to fly, they could bring air travel to a complete stop. Their jobs are even more specialized — and thus harder to replace — than TSA agents. While private sector workers can face sanctions for striking, the potential penalties are far less severe than the penalties federal workers face. And while some travelers would be frustrated, airline workers would likely win massive public support if they told the country they were striking to prevent airplanes from crashing.

Nor would all flight attendants across the country have to strike to make a significant impact. If workers at even a single hub airport like JFK in New York, Hartsfield in Atlanta, or O’Hare in Chicago stopped working, delays and cancellations would quickly spread across the country as planes sat idle. That would create the kind of crisis that even conservatives have argued would quickly end the shutdown.

In the midst of one of the largest employer lockouts in American history — and following the historic success of the Los Angeles teachers strike — airline workers have the opportunity to demonstrate how a small but well-organized group of workers can have an outsized positive effect on the country as a whole. In Nelson, they may have the militant leader willing to help organize them to do it. Will flight attendants end the shutdown?