- The union representing air traffic controllers sues President Trump over shutdown.
- Air traffic controllers have been deemed essential government workers and are showing up without pay.
- The government shutdown started Dec. 22 and is one of the longest in history.
The union representing the United States' air traffic controllers is suing the Trump administration over pay that's frozen as part of the partial government shutdown, a sign of increasing tension between federal workers and the government as the impasse edges closer to becoming one of the longest ever.
The Federal Aviation Administration's air traffic controllers are among the 420,000 federal employees who have been deemed essential and have been ordered to work without pay during the shutdown, which began on Dec. 22 due to an impasse over funding for a wall along the U.S. southern border.
The effects of the shutdown are already rippling through aviation, stalling the required federal approvals for new jets and routes, as well as certifications for new mechanics and other workers.
The White House did not immediately return a request for comment.
The shutdown is also extending to the thousands of passenger screeners at U.S. airports.
Transportation Security Administration officers have been calling out sick in greater numbers than at the same time last year, the agency said. The some 51,000 TSA officers on Friday missed their first paycheck since the shutdown began. Some told CNBC they planned to dip into savings to make up for the lost check.
The suit, filed Friday in federal court, alleges the government "unlawfully deprived" thousands of air traffic controllers of pay "without due process."
The National Air Traffic Controllers Association represents some 19,000 FAA employees, which includes 14,000 air traffic controllers. They have already missed a paycheck, according to union spokesman Doug Church.
This story developing. Check back for updates.