Air traffic controllers at Chicago's O'Hare International Airport put passenger planes on course for mid-air crashes twice last year, with disaster only averted by the pilots' actions, according to newly released interviews from the National Transportation Safety Board.
The NTSB said the first close call came on May 16, 2011, when a SkyWest Airlines flight from Michigan was on "a collision course" with an ExpressJet Airlines flight that was taking off, bound for Buffalo.
Ultimately, after swift action by the pilots, the planes "passed in close proximity" to one another.
According to Federal Aviation Administration radar, the SkyWest flight was "about 275 feet above and 480 feet behind" the Buffalo flight.
"After I was able to gain a little composure back after nearly being killed, I keyed up the mike and yelled to the tower controller, 'What the [expletive] was that?' I got no response," the captain of the ExpressJet flight said in a statement.
Only months later a second incident -- the same situation, the same runways -- occurred when on Aug. 8, 2011, there was a "near mid air collision" involving a Chautauqua Airlines flight from Wisconsin to O'Hare that passed in close proximity to a Trans State Airlines plane leaving for Moline, Ill.
The Chautauqua flight was only "125 feet above and 350 feet in front of" the Trans State plane.
To date the NTSB has not reached any conclusions on what caused these two close calls. The FAA has stated that it has taken corrective action.
Now a Virtual Intersection Warning goes off and the controllers responsible for the two troublesome runways at O'Hare, the country's second-largest airport, sit right next to each other to eliminate confusion.
One of the problems, according to DePaul University professor Joseph Schwieterman, a transportation expert, is that O'Hare is an "older airport with crossing patterns" that make it "an incredibly, busy, difficult place."
"You have crossing runways, you have congestion," he warned in an interview with ABC News. "You really need a perfect air traffic control environment to minimize those risks. Little slipups like we saw here in the last couple of years lead to big risks and I think that's been a wake-up call.
"I think what the public and the NTSB are looking at here is that it took overt pilot action to avoid an error," he noted. "That suggests that in some ways, we got lucky. That's clearly cause for concern."
In 2011, there were a total of seven serious near-collisions nationwide, relatively unchanged from the year before.
The FAA, through a spokesman, cited that 99.99 percent of airline operations went off without a hitch. Pilots and passengers, however, may wish that that number were even higher.