The US government shutdown is taking its toll on the country's air traffic control network.

According to the National Air Traffic Controllers Association or NATCA, air traffic controllers are not only understaffed but also working without pay.

The FAA's ATC training center is closed during the shutdown while newly trained controllers have been put on furlough, limiting an already depleted staff.

According to the union, this will lead to increased flight delays.

As the US government shutdown drags on into another week, its effects are being felt across the nation. America's air transport system is certainly not immune from its effects.

Stuck in the middle of the shutdown is America's beleaguered air traffic controllers.

According to the National Air Traffic Controllers Association or NATCA, there are currently fewer fully trained controllers than at any point in the last 30 years.

With the government shut down, the country's air traffic control centers are not only understaffed but also currently working without pay, NATCA, the union that represents roughly 20,000 air traffic controllers, engineers, and aviation professionals, said in a statement.

"This staffing crisis is negatively affecting the National Airspace System, and the shutdown almost certainly will make a bad situation worse," Paul Rinaldi NATCA's president said in the same statement. "Even before the shutdown, controllers have needed to work longer and harder to make up for the staffing shortfall."

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The Federal Aviation Administration has temporarily closed its ATC training center in Oklahoma City, Oklahoma as a result of the shutdown while newly trained controllers have been put on furlough.

The result of all of this, according to Rinaldi, is increased flight delays for the traveling public.

"If the staffing shortage gets worse, we will see reduced capacity in the National Airspace System, meaning more flight delays," he said. "A lack of adequate staffing also hurts the FAA’s ability to develop new technology and modernize the system, and controllers also don’t get the amount of time they need for training."

The US federal government shut down on December 21, 2018, after the Congress failed to pass a new spending bill due to disagreement over the Trump Administration's demand for $5 billion in border wall funding.