Air traffic controllers' union chief says tension is at an 'all-time high' as workers miss their first full paycheck of the government shutdown

• Frustration is soaring as air traffic controllers miss their first paychecks, the union chief says. • "The tension is at an all-time high," Nick Daniels, the president of the National Air Traffic Controllers Association, said. • Over 13,000 controllers are expected to remain on duty without pay amid the shutdown.

Air traffic controllers are still guiding the skies, but without pay and under mounting strain as the government shutdown drags on.

"We had a partial paycheck last time, so air traffic controllers have worked over 120 hours now with no pay. The tension is at an all-time high," Nick Daniels, the president of the National Air Traffic Controllers Association, or NATCA, told NBC News on Wednesday.

"Air traffic controllers are not only stressed, they're not only fatigued, they