Two similar near-collisions within months of each other last year at Chicago’s O’Hare International Airport are under investigation by the U.S. National Transportation Safety Board.
Regional jetliners in both cases came within several hundred feet of colliding at the same part of the airport, a point where arriving and departing planes cross. Controllers are supposed to monitor flights to prevent such incidents, according to NTSB reports released today.
Pilots in both cases told investigators they had to take evasive action to avoid a collision, according to the reports.
The captain of closely held Trans States Airlines Inc.’s Flight 3367 said he pushed the jet’s yoke forward as the jet neared takeoff speed Aug. 8, 2011, to keep it on the ground as Republic Airways Holdings Inc.’s Chautauqua Airlines Flight 5021 flew overhead, according to the reports.
At the same time, a controller warned the pilots to stay low. “That advice may have been too late if we didn’t see him first,” the unnamed pilot said.
The Chautauqua jet passed 125 feet above and 350 feet in front of the Trans States plane, according to the NTSB.
The pilots of ExpressJet Airlines Flight 6075, a departing plane, said they stayed 100 feet off the ground on May 16, 2011, to avoid SkyWest Inc. Flight 6958, which passed 275 feet above them, according to the NTSB. ExpressJet is a unit of SkyWest.
“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?’” the unidentified captain told investigators, according to a transcript included in the NTSB reports.
“Sorry about that,” a controller replied.
In some wind and weather conditions, O’Hare arrivals from the west pass over another runway used for departures. Controllers are supposed to act like traffic police during that configuration, allowing an arrival to pass before clearing a departure.
The NTSB today opened its public docket on the cases, which contain factual reports and summaries of witness interviews. The safety board hasn’t issued probable causes for the incidents.
The U.S. Federal Aviation Administration has taken several steps to improve safety at the airport since last year, the agency said in an e-mailed statement.
“Since these measures were implemented, there have been no repeats of these incidents,” the agency said.
The NTSB reports point to several issues that may have contributed to the incidents.
The automated warning system that alerts controllers to a collision on the runways didn’t sound in either case because it wasn’t programmed to notice a hazard just above the ground, according to the NTSB. It could have issued an alert with a software change, according to the safety board.
The FAA altered the warning system so that it now issues an alert if planes on the two runways get too close, according to the agency statement.
The O’Hare tower configuration made it difficult for controllers working different runways to communicate, several witnesses told investigators.
The FAA also moved the desks where the controllers work closer together, it said.
In both cases, distractions at the airport may have kept controllers from noticing the potential for a collision. A White House plane had landed at O’Hare minutes before the May 16 incident and controllers were coordinating with the U.S. Secret Service, according to the safety board.
Incidents in which planes got too close together due to controller safety errors more than doubled from 2008 to 2011, according to a Government Accountability Office study.
The FAA has attributed the increase mainly to a new policy to encourage better error reporting and said most cases were minor. The GAO said all of the increase can’t be attributed to the policy.
One incident occurred July 31 near Washington’s Ronald Reagan National Airport when a communication mix-up led controllers to clear two planes to take off toward a flight lining up to land in the opposite direction.
Those planes didn’t pass as closely as the aircraft at O’Hare. Two of the planes in the Washington incident came within 0.94 mile of each other after the departing craft had climbed 800 feet above the other.