Among the potential casualties of the automatic $85 billion in spending cuts is the Federal Aviation Administration, which would see its budget sliced by more than $600 million.

It has led the National Airline Traffic Controllers Asso. (NATCA) to predict that Chicago’s O’Hare Airport could see a thirty percent drop in flight arrival rates if Congress fails to reach a deal to avert the round of multi-billion dollar budget cuts by Friday.

Currently, 114 flights come into O’Hare per hour, according to NATCA. If the cuts kick in on Friday, the union expects that figure to drop to 72 arrivals per hour. In addition, airline traffic controllers could face 11 days of mandatory furloughs.

It is a combination a local union representative believes could lead to less flights in the air and more delays on the tarmac as fewer controllers take on more responsibilities.

“In order to mitigate being overloaded, you may have delays going in and out of other airports as well. The satellite airports around Midway Airport as well,” said James Hall, an airline traffic controller in Chicago and facility representative for the local chapter of NATCA. “It would be challenging to try to figure out a schedule and then from day to day we would have to figure out […] ways to work the traffic with less people.”

Hall said each day 56 air traffic controllers are monitoring Chicago’s airspace. With the cuts in effect, that number could dip to 48.

”[…]Travelers, general aviation pilots, airlines, businesses and the military will feel the effects of the cuts in the form of a reduction in airport and air traffic control services […] increased delays and costs to users, and lags in air traffic modernization. These cuts will be significant, and their effects will likely have long-lasting consequences,” a NATCA statement read on its website.

But airline controllers are not the only group that will be affected by the cuts, according to Pres. Barack Obama’s administration and other federal officials. Illinois, in particular, could lose millions of dollars in funding for elementary and secondary education, along with cuts to law enforcement, environmental and energy funding.

Rep. Peter Roskam (R-Ill.) said he doesn’t want to see a “disruption to major services” in a phone interview Wednesday, but he called on Pres. Obama to help forge an accord.

“I think the president is over-characterizing things at this point. But that’s not to say that we should not replace the sequester. We should. There’s far more thoughtful ways to meet these essential government services, but the federal government has to live within its means,” Rep. Roskam said.

Lawmakers in Washington have until Friday to avoid the cuts.

“I don’t know if I’m eager for Friday, I just would like to know what’s going on. So we can move and come up, formulate a plan to move on, to deal with whatever comes our way,” Hall, the airline traffic controller in Chicago, said in a phone interview.