Every day of the federal government shutdown air traffic controllers calling out sick have caused flight delays, Transportation Secretary Sean Duffy said Friday.

ŌĆ£ItŌĆÖs different every day,ŌĆØ he told reporters at a news conference at Philadelphia International Airport. ŌĆ£The averageŌĆ” is about 5% of our delays come from staffing shortages with air traffic controllers. WeŌĆÖve gone up as high as 53% of the delaysŌĆ” because of staffing shortages.ŌĆØ

On Friday, seven air traffic control facilities were short-staffed, including the control towers in Dallas Fort Worth, Newark and Phoenix, TRACONs which handle flights approaching and departing Houston and Newark, and centers, which handle high altitude flights around Atlanta and Denver.

There have been 217 staffing shortages reported since the start of the shutdown, more than four times the number reported on the same dates last year. Air traffic controllers, like Transportation Security Administration screeners, are required to work during the government shutdown but are not being paid.

ŌĆ£Their paycheck is going to be a big fat zero,ŌĆØ Duffy said. ŌĆ£ThereŌĆÖs great frustration. ThereŌĆÖs anxiety because as any one of you, you look at the expectation that a paycheck comes in and then you plan for that.ŌĆØ

Controllers, approximately 10,800 federal workers, will receive the first $0 paycheck on October 28. On October 14, they received a partial paycheck, about 90% of the normal total, for hours worked before the shutdown started.

The lapse in government funding makes air travel ŌĆ£less safe,ŌĆØ according to Nick Daniels, president of the National Air Traffic Controllers Association, the union which represents controllers.

ŌĆ£As this shutdown continues and air traffic controllers are not paid for the vital work that they doŌĆ” that leads to an unnecessary distraction, and they cannot be 100% focused on their jobs, which makes this system less safe,ŌĆØ he said. ŌĆ£Every day that this shutdown continues, tomorrow, weŌĆÖll be less safe than today.ŌĆØ

Duffy noted the FAA will slow planes down or cancel flights if they cannot be operated safely.

ŌĆ£If we donŌĆÖt have enough controllers, if we have controllers that are more stressed and less able to do the jobŌĆ” we will reduce the capacity of airplanes taking off and landing, or we will cancel flights,ŌĆØ Duffy said. ŌĆ£IŌĆÖm less concerned about you getting there on time. I want you to be safe.ŌĆØ