Bad data unfairly play up GA midair threat
By Paul Richfield
Flaws in the way the FAA collects and uses air safety data may provide an unrealistic view of the collision threat general aviation aircraft pose in busy terminal airspace, according to the Department of Transportation’s investigative arm.
Of 66 total near midair collision (NMAC) reports that airline crews filed in fiscal year 2007, 16 (24 percent) were later determined to be no-hazard events. Yet they are still classified as near midair collisions in FAA records.
“In our opinion, the lack of a procedure for reclassifying no-hazard events may contribute to misperceptions regarding the actual safety risk posed by an incident,” the DOT’s Office of Inspector General (OIG) said in its April 24 report to Congress.
The OIG initiated the review in response to a June 11, 2007, letter from Sen. Hillary Rodham Clinton (D-N.Y.), which expressed concern over a rash of NMAC reports filed in May 2007. These reports—five in all—detailed alleged traffic conflicts between commercial and GA aircraft.
After a six-month investigation, the OIG determined that the five NMACs in question were independent, unrelated events with no obvious common root causes. Four of the five were determined to be “no hazards”—just one was classified as a “potential” collision risk.
In each of these incidents, airline pilots on instrument flight plans filed NMAC reports after being “surprised” by the location of VFR aircraft in nearby airspace, the OIG said, “but the incidents actually posed no risk to safety regardless of any action taken by the pilots.”
The DOT recommended that the FAA evaluate whether “commercial IFR arrival and departure routes” within New York airspace should be redesigned or restricted to minimize potential conflicts with VFR air traffic.
It also proposed an analysis of arrival procedures at Newark Liberty International Airport, to identify measures for staggering approaches and reducing go-arounds when certain runway configurations are used.
Lastly, DOT wants the FAA to restructure the NMAC reporting process, to more accurately reflect the actual safety risks reported events pose. This could include reclassifying no-hazard events, redefining NMAC criteria, or revising the term “NMAC.”
“The definition of a near midair collision is highly subjective. And when you use an imprecise measuring instrument, you only get imprecise data. Fortunately, we haven’t had a midair collision between a GA aircraft and an air carrier since the accident over Cerritos, Calif., in 1986,” said Bruce Landsberg, executive director of the AOPA Air Safety Foundation.
“The use of TCAS on airliners and collision avoidance equipment on board an increasing number of GA aircraft—along with constant vigilance by pilots—proves that the most regulated transportation system in the world is working,” he added.
May 8, 2008
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