The nation’s air travel system slowly began to recover Saturday after an alleged act of employee sabotage at a large regional air traffic control center brought Chicago’s two international airports to a halt.

At the height of the travel misery Friday, more than 2,000 flights in and out of O’Hare and Midway airports had been canceled, sending waves of travel disruption rippling across the country.

Authorities say a contract employee started a fire Friday morning in the basement telecommunications room of a control center in the Chicago suburb of Aurora and then attempted to commit suicide by slashing his throat. Brian Howard, 36, of Naperville, was charged with destruction of aircraft or aircraft facilities, a felony. The FBI said Howard remains hospitalized and no court date has been scheduled.

As of late Saturday afternoon, total Chicago flight cancelations for the day stood at more than 780 — still a damagingly high number, but an improvement. Southwest Airlines, the dominant carrier at Midway, had hoped to resume a full flight schedule Saturday, but had to cancel all flights between 10 a.m. and 2 p.m. CDT.

Lines remained long at O’Hare, which is a major U.S. hub. Many travelers stranded overnight slept on cots provided by the airport, in scenes reminiscent of winter storm disruptions.

The Federal Aviation Administration facility in Aurora, about 40 miles west of downtown Chicago, handles planes cruising at high altitudes through the air space as well as those just beginning to approach or completing a departure from airports in the Chicago area. It remained shut down Saturday, and its responsibilities have been transferred to centers in Cleveland, Indianapolis, Kansas City and Minneapolis. The FAA’s command center in Warrenton, Virginia, was also working to increase the traffic flow.

The widespread disruption left some aviation analysts, travelers and politicians calling for a smoother backup plan and wondering how one person could be in a position to wreak so much havoc.

“Chicago O’Hare International Airport cannot be brought to a screeching halt,” said Republican Sen. Mark Kirk, of Illinois. “I want to see not only an immediate review by the FAA of the screening process at the Chicago Air Route Traffic Control Center in Aurora, but also a report within 30 days outlining changes the FAA will make to prevent any one individual from having this type of impact on the heart of the United States economy.”

An FAA spokeswoman did not immediately have a response, but an agency statement on Friday’s fire emphasized that air space management was immediately transferred to other facilities.

The FAA said it conducts employee background checks on contract workers like Howard who have access to FAA facilities, information or equipment. Contract employees, like other staff at the Aurora facility, also must have their identification inspected by a perimeter guard and must swipe their cards to gain access to the building.

Howard entered the building around 5 a.m. Friday, and about 30 minutes later posted a suicide note on Facebook in which he apologized to loved ones for leaving “a big mess,” according to a federal criminal complaint.

“Take a hard look in the mirror, I have,” the post says, according to the FBI special agent who prepared the complaint. “And this is why I am about to take out ZAU and my life.” ZAU is the three-letter designation for the Aurora facility.

Minutes later, someone at the facility called 911 to report the fire. A relative who saw the Facebook post also alerted authorities. Paramedics followed a trail of blood past a gas can, two knives and a lighter and found the suspect slashing his throat, the complaint said. He also had cuts to his arms.

One of the paramedics pulled the knife from his hands as the suspect called out, “Leave me alone,” according to the complaint.

Howard worked at the facility for eight years and was involved with the facility’s communications systems. He was recently told he was being transferred to Hawaii.

If convicted, he could be sentenced to up to 20 years in prison.

The FAA was still assessing the extent of the damage at the site, and it was unclear when operations there would be fully restored. On Saturday, workers began drying out equipment damaged by water from the building’s sprinkler system, the agency said.

(AP)