An apparent miscommunication between air-traffic controllers led to a close call between two private planes flying in central Wisconsin, marking the second error in less than a week attributed to an FAA radar facility near Chicago, officials said Sunday.
One of the planes had taken off earlier from Midway Airport in Chicago, according to the Federal Aviation Administration.
The controller error on Saturday allowed the two aircraft to come into close proximity as one plane was coming in for a landing and the other had just taken off from a different airport in an area about 30 miles southwest of the Wisconsin Dells.
The incident occurred at 11:44 a.m. Saturday when a four-seat Cirrus SR22 plane that had departed the Tri-County Regional Airport near Lone Rock, Wis., came within 500 feet vertically of a Cessna Caravan 208 turboprop plane en route from Midway to a private airport in Leeward County, Wis., 13 miles northwest of Lone Rock.
FAA safety regulations require at least 1,000 feet of vertical separation and at least 5 miles laterally between aircraft. The lateral distance between the two planes was 2.8 miles at the closest point, FAA spokesman Tony Molinaro said.
It was not immediately known how many people were on board the planes or whether the pilots were aware of their close brush when they passed each other at about 3,800 feet above the ground, officials said.
The controller mistake, which happened at the FAA's Chicago Center radar facility, is the second most severe type of error that the FAA says a controller can make, officials said. It was the second serious operational error committed by controllers at the suburban Chicago FAA facility within the past week, and the fourth serious error since October, records show. Only one error of that severity occurred within the previous 12 months at the radar facility.
While the controllers union cited staffing issues and fatigue as factors in this operational error and one four days earlier involving a near-collision of two airliners over Indiana, the FAA said it does not see a pattern.
"Two errors in a week at a center does not define a problem. We need to look at it from the proper perspective," Molinaro said. "At Chicago Center, they handle about 3 million flights each year, so one or two controller errors in a week does occur."
On Saturday, confusion over how wide an area of airspace to clear for the Cirrus plane climbing out of the Lone Rock airport occurred between controllers at a FAA facility in Madison, Wis., and controllers at Chicago Center, according to a preliminary investigation and an interview with the president of the controllers union.
The Madison facility asked a Chicago Center controller to keep all other traffic crossing the area out of airspace that was 4,000 feet and below, to ensure no conflicts would occur between the ascending Cirrus and other aircraft flying through the area.
The Chicago Center controller complied, but only for an area within a 5-mile radius of the Lone Rock airport.
The Cirrus was traveling to Faribault, Minn., south of the Twin Cities.
"The coordination was poor. Madison was thinking one thing, and we were apparently thinking something else," said Jeffrey Richards, president of the air-traffic controllers union at Chicago Center. "These two planes went right past each other, and we weren't talking to either of them. That's bad."
According to Robert Bond, who owns but was not flying the Cirrus involved in the near-miss on Saturday, the plane is furnished with equipment that tracks the location of nearby planes, even if FAA controllers fail to properly monitor and alert fliers of oncoming traffic.
"When anything even approaches close, a screen pops up a display that shows exactly where the traffic is and exactly its bearing," Bond said. "As long as the other plane has a transponder, then it will show any plane around us and whether or not it's descending."
The near-miss occurred four days after a Chicago Center controller mistakenly directed a Midwest Airlines plane to descend into the path of a United Express jet bound for O'Hare International Airport.
The two planes came within seconds of a midair collision at 25,000 feet over Indiana on Tuesday. A cockpit safety device alerted the pilots of the Midwest Airlines plane. The Midwest pilots averted disaster by climbing out of the way of the United Express plane.
In the aftermath of the weekend incident in Wisconsin, Richards said new procedures are needed to erase uncertainties about how big an area to block near an airport when a request is issued about clearance for an airplane's departure.
But he attributed the recent errors at his facility to controllers being fatigued.
"Our guys are tired and have been working short for 2 1/2 years now," Richards said. "It's getting worse."
He said the area of the Chicago Center facility where Saturday's controller error occurred is supposed to be staffed with 11 fully certified controllers. Actual staffing at the time was nine controllers and three controller-trainees, he said.
FAA officials say staffing levels are adequate at its facilities, even though they acknowledge the challenge being posed by a wave of retirements by veteran controllers. More than 1,550 controllers left the FAA in fiscal 2007.
"The data show that the number of controller errors is not directly related to the number of FAA controllers," Molinaro said. "In years when we had many more controllers, we also had many more errors."
In addition, Molinaro said the data do not support the controllers union's contention that errors are linked to fatigue.
"Most errors occur during the first 20 minutes that a controller is on position. Instead, [the lack of] situational awareness plays a major role in creating controller errors," he said.