Thomas Delgado, a teacher at the Federal Aviation Administration's Air Traffic Control Academy in Oklahoma City says the uncertainty stemming from the shutdown from the federal government shutdown is adding stress to an already stressful profession.

"We're short still of controllers," said Delgado, who lives in Colorado. "And now we're going to have a gap. The longer we wait, the longer we have to wait until the funding is reestablished, that gap is going to get bigger and bigger."

Delgado contacted Next with Kyle Clark this week, as the shutdown approaches its 20th day. It's forced the academy to temporarily close and send everyone home - including students, instructors and administrative staff.  There were about 200 students at the academy at the time the shutdown started.

"The amount of money that's being lost is huge," Delgado said. "The students' per diem has to start all over again. That's $35 to $45 per student for three to four months."

Delgado, who used to be an air traffic controller himself, says the big impact of the shutdown will be on the input of new controllers into the system.

"We tend to burn people out," he said. "And that's not good for the aviation environment. Controllers don't like uncertainty.  And when you start talking about them not being paid on time or the possibility that there's not going to be new people coming up that will help spread the workload out - that's going to cause even more stress."

In a statement posted to the National Air Traffic Controllers Association website, the number of certified controllers has dropped in recent years and 18 percent of controllers working now are currently eligible to retire. NATCA President Paul Rinaldi says in the statement that the limited number of controllers already meant current staff members were working long weeks and long days.

NATCA says that a stop to hiring and training new staff means fliers can expect flight delays as the shutdown continues.

Even before the uncertainty of the shutdown, Delgado says the Air Traffic Control Academy typically loses between 30 and 60 percent of its students because the work is so challenging.

CNN reported last week that the shutdown has affected the Transportation Security Administration, as well. Their reporting said there have been "excessive absences," TSA officers have called out of work. A TSA spokesperson said CNN's statistics were exaggerated.