Air-traffic controllers, along with many other federal employees in the US, have been working unpaid during the government shutdown, which began on December 22.

On Thursday, several air-traffic controllers who missed their first paycheck posted photos of their $0 pay stubs on Twitter.

Aviation-industry workers, along with some political leaders, are rallying in Washington, DC, on Thursday to demand an end to the shutdown.

As the US government shutdown continues into its third week, federal employees who have been working unpaid are missing their first paychecks.

On Thursday, many air-traffic controllers around the US received pay stubs showing $0 in income. Some have even posted photos of them on Twitter.

It should be noted that the employees working unpaid are due to receive back pay once the government reopens. Those who were furloughed, or temporarily laid off, might not be so lucky and may not get paid.

Read more: United, Alaska, and Spirit flight attendants are warning Trump, Pelosi, and McConnell that the government shutdown is doing real damage to the airline industry

The National Association of Air Traffic Controllers, a union that represents roughly 20,000 controllers around the US, said the shutdown was creating additional strain on people who already carry a heavy burden.

"Even though air traffic controllers and traffic management coordinators remain on the job, dedicated to the safety of every flight, they don't know when they'll receive their next paycheck and that adds more stress to an already stressful profession," NATCA said last week in a letter to congressional leaders.

According to the union, there are fewer fully trained controllers now than at any point in the past 30 years.

The Air Line Pilots Association International, as well as two major unions representing flight attendants, have also sent letters to President Donald Trump and congressional leadership, echoing NATCA's concerns.

"Flight Attendants across the industry ask you to end the shutdown now," the flight-attendants' unions said in their letter. "This is a matter of safety, security, and economic concern."

They added: "We are in awe of the transportation security officers, air traffic controllers, and other workers deemed as essential employees for their patriotism in coming to work without the certainty of a paycheck or any resolution to this shutdown."

Read more: Delta, United, and JetBlue pilots are warning that flying will become more dangerous as the government shutdown continues

Aviation-industry workers, along with some political leaders, are rallying in Washington, DC, on Thursday to demand an end to the government shutdown, which began on December 22.

—Rep. Mark Pocan (@repmarkpocan) January 10, 2019