O.C. Disaster Changes Plane-Distancing Policy : Aviation: Citing crash linked to 757 wake turbulence, FAA will require aircraft to stay 4 miles back instead of 3.
Citing a crash that killed five people in Santa Ana last December, the Federal Aviation Administration has adopted a policy that will require smaller planes to stay farther behind Boeing 757 jetliners to prevent accidents caused by their potentially hazardous wake turbulence.
But the regulatory agency’s actions--part of a detailed set of new policies on 757s--fall short of safety recommendations made by the National Transportation Safety Board earlier this year. And aviation-safety experts and pilots’ advocates termed the changes merely a “first step” toward making the skies safer for aircraft landings and takeoffs behind 757 jetliners.
FAA Administrator David R. Hinson outlined the new policy in recent days in a letter to NTSB Chairman Carl W. Vogt.
Beginning July 1, the FAA will require that air-traffic controllers handling landings to keep aircraft four miles behind 757s--instead of the current three-mile minimum--to protect them from the miniature hurricanes produced by rapid air movement across the larger aircraft’s wings.
The NTSB in February had recommended that the FAA adopt minimum separation distances of up to six miles behind 757s. The FAA, however, is not bound by NTSB recommendations.
At least two crashes that took a total of 13 lives and three other serious accidents have been linked to wake turbulence from 757s since December, 1992. Because it could potentially decrease the number of flights at the nation’s airports and cut into revenues of the hard-hit airline industry, the FAA has been reluctant to increase separation distances between 757s and tailing airplanes.
While the NTSB does not consider the 757 to have any structural flaws, researchers have speculated that its unique, sleek-wing design may be the cause of the turbulence that can be unusually powerful for an aircraft of its size.
The NTSB has found that because 757s and other newer jets can slow down quicker than older jetliners, trailing aircraft can inadvertently close in too quickly and fall below the 757’s descending flight path--a danger zone where aircraft can encounter wake turbulence and suddenly be thrown out of control.
Both fatal accidents happened when smaller jets flew into 757 wake turbulence as they were preparing to land.
The Dec. 15 Santa Ana crash occurred when a twin-engine corporate jet was on a landing approach to John Wayne Airport. The jet, which was 2.1 miles behind a Boeing 757, went out of control and slammed nose-first into the ground near the Santa Ana Auto Mall. All five aboard, including the top two executives of the In-N-Out Burger chain, were killed. The NTSB is still investigating the accident, but turbulence from the 757 is said to have played a part.
The other fatal crash occurred in Billings, Mont., in 1992. Eight people were killed.
NTSB spokesman Mike Benson said the safety board will review the FAA’s new policies and draft a formal response over the next several weeks.
Bob Flocke, a spokesman for the Air Line Pilots Assn., said, “We think it’s a good beginning. It certainly addresses part of our concern. But it doesn’t, for instance, address separation on departures.”
The Air Line Pilots Assn., the largest pilots’ organization in the world, recently issued its own advisory on 757s, recommending that pilots of smaller aircraft--even MD-80s and DC-9s--remain five miles or at least “two minutes” behind 757s on final approach, Flocke said. The organization also has recommended that pilots ask the control tower for extra time when taking off behind 757s, Flocke said, to give more time for the 757 turbulence to diminish.
Despite concerns from other corners of the aviation industry, the FAA said it believes that the four-mile separation is safe enough--for now.
“The FAA believes that this interim increased separation will provide an extra margin of safety without unnecessarily impacting system capacity,” FAA Administrator Hinson wrote in a May 20 letter outlining the changes to NTSB Chairman Vogt.
The four-mile separation, Hinson wrote, recently was adopted by the Civil Aviation Authority in Great Britain and “has significantly reduced the number of reported incidents” there.
As part of its new policies on 757s, Hinson said, the FAA is embarking on a two-year test with the help of the National Aeronautics and Space Administration to determine the precise level of danger 757 wake turbulence poses. The four-mile separation limit will remain in effect until testing shows whether additional distance is necessary.
After its own investigation, the NTSB last February unanimously advised the FAA to overhaul its 20-year-old aircraft weight classification system, which is used to set separation distances.
The FAA, however, said an overhaul was not warranted now, but that it would study the issue.
Leo Garodz, a former FAA manager who was among the first to bring the 757 wake turbulence problem to the agency’s attention in 1991, said the new policies represented an “initial step,” but nothing more.
“It’s a beginning, but it’s only a beginning, because there’s going to be another accident, because things are not that precise at airports when there is a heavy traffic load,” Garodz said.
The FAA said it also plans to require air controllers to be more cautious when dealing with planes behind 757s; educate pilots of 757s on the potential danger their aircraft poses to other planes; encourage 757 pilots to use established approach paths so other planes don’t unwittingly fly into their wake; and require air controllers to complete an annual course in wake turbulence.
Canadian aviation officials have recently begun to require five or six miles of separation behind 757s, depending on the size of the trailing aircraft. Their counterparts in the United Kingdom require a minimum of four-, five- or six-mile separation, depending on aircraft size.
