Airlines were scrambling to accommodate travelers whose flights were canceled after a contract employee allegedly set fire at a suburban Chicago air traffic control center where he worked, halting flights at two of the nation's busiest airports.

Brian Howard, 36, of Naperville, Illinois, was charged Friday with destruction of aircraft or aircraft facilities, a felony. When paramedics found him, he was trying to cut his own throat, according to the criminal complaint. The FBI said Howard remains hospitalized and no court date has been scheduled.

The fire halted all traffic in and out of O'Hare and Midway airports. Delays and cancellations rippled through the air travel network from coast to coast after the fire. The ground stoppage at O'Hare and Midway raised questions about whether the Federal Aviation Administration has adequate backup plans to keep planes moving when a single facility has to shut down.

By Friday night, more than 2,000 flights in and out of Chicago had been canceled. Flights resumed after a five-hour gap, but planes were moving at a much-reduced pace, and no one could be sure when full service would be restored.

The FAA said in a statement Friday evening that it was managing the Aurora facility's traffic through centers in Cleveland, Indianapolis, Kansas City and Minneapolis. The agency said it would continue working with those centers over the weekend to reduce disruptions.

The fire forced the evacuation of the control center in Aurora, about 40 miles west of downtown Chicago. It was the second unexpected shutdown of a Chicago-area air traffic facility since May.

Howard worked for the FAA contractor that supplies and maintains communications systems at air traffic facilities, said Jessica Cigich, a spokeswoman for Professional Aviation Safety Specialists, the union that represents FAA technicians. Howard was recently told he was being transferred to Hawaii, according to the complaint filed in U.S. District Court in Chicago.

The complaint says a relative who saw a suicidal Facebook note posted on Howard's account early Friday alerted authorities. Meanwhile, a 911 call from the control center brought a suburban fire department to the scene, where paramedics followed a trail of blood past a gas can, two knives and a lighter, the complaint said.

Howard told the paramedics who found him, "Leave me alone," the complaint said.

Howard used a key card to access the center, according to the complaint, and video surveillance shows him dragging a rolling suitcase as he entered. Authorities don't believe there's any surveillance video of the crime itself, Thomas Ahern, a spokesman for the Bureau of Alcohol, Tobacco, Firearms and Explosives, said.

When the center was evacuated, management of the region's airspace was transferred to other facilities, FAA spokeswoman Elizabeth Cory said.

The shutdown quickly spread travel misery around the country, with airports as close as Milwaukee and as far as Dallas canceling flights.

Online radar images at one point showed a gaping hole in the nation's air traffic map over the Upper Midwest. Some passengers already in the air headed for Chicago wound up elsewhere. Southwest Airlines said it scrapped all of its flights at Midway and Milwaukee for the entire day.

"This is a nightmare scenario when we thought systems were in place to prevent it," said aviation analyst Joseph Schwieterman of DePaul University in Chicago. "Technology is advancing so fast that ... there's less of a need for air traffic control to be so geographically oriented. I think the FAA's going to find itself under a microscope."

The disruption was also likely to deliver a financial hit to airlines, Schwieterman said.

The FAA's statement did not address the delays, and a spokeswoman in Chicago did not respond to a request for comment about the agency's backup planning.

Brothers Glenn and Gary Campbell, of suburban Chicago, had planned to travel to the Orlando, Florida, area to attend their father's 80th birthday party. Instead, they settled for refunds.

"That it is so easy to disrupt the system is disturbing," said Gary Campbell, a carpenter from Crystal Lake, Illinois. "They need to see how to make sure this kind of thing doesn't happen again."

In May, an electrical problem forced the evacuation of a regional radar facility in suburban Elgin. A bathroom exhaust fan overheated and melted insulation on some wires, sending smoke through the facility's ventilation system and into the control room. That site was evacuated for three hours, and more than 1,100 flights were canceled.

The Aurora facility, known as an enroute center, handles aircraft flying at high altitudes, including those approaching or leaving Chicago airports. Air traffic closer to the airports is handled by a different facility and by the control towers at the airfields.