Asked by CNN's Jim Sciutto whether the airport delays are a direct result of the government shutdown, Trish Gilbert, Executive Vice President of the National Air Traffic Controllers Association said, "Absolutely."
"We predicted that you cannot continue to operate a system this complex for this long without the support structure of the people that are furloughed," Gilbert said.
While Gilbert doesn't know the details of every absence, she said there are concerns that stress and a lack of sleep could mean some air traffic controllers aren't able to do their jobs.
"We are already short-staffed," she said. "So now you've added the stress to air traffic controllers and their personal circumstances. And they're not sleeping at night. Now we're concerned that they're not fit for duty."