A Crowded Sky--More Planes, Less Separation

The Federal Aviation Administration has reduced the separation required between certain commercial aircraft on their final approach to Los Angeles International Airport as part of an attempt to increase U.S. airport capacity.

The reductions are part of a test that began quietly March 4, in which separation has been cut from three miles to 2 1/2 miles between certain jets approaching the same airport runway in good weather.

FAA officials say the “demonstration” is designed to show that reduced separation will not jeopardize safety and will enable more flight operations at the already congested airport and at others around the nation. The FAA says the test has resulted in no safety problems so far.

Precursor to More?

But some aviation experts are concerned that a reduction in safety margins is not risk-free and is a precursor to further reductions. And so far, several pilots each day are refusing to close in, according to FAA supervisors in charge of air traffic control at the airport.

“We are reducing the margins, the cushions,” said one commercial pilot. “Obviously, if we have three miles we have more of a margin than when we are closer to his tail.”

“I think there is an equivalent level of safety in this demonstration or we wouldn’t be doing it,” says Joe Foster, an FAA official in Los Angeles involved with the program. “There are safeguards built in.”

The Air Line Pilots Assn. agreed to participate in the program only with “reluctance,” according to a letter sent to FAA officials recently from the union’s Washington headquarters. The reluctance stemmed from several potential safety concerns, although the union stresses that it does not regard the tests as dangerous. Nevertheless, in response to concerns of pilots, the FAA agreed to make the demonstration voluntary.

Industry Concession

Union officials said they agreed to the test only after airline industry officials dropped plans to conduct the reduced separation tests during bad weather conditions when aircraft are guided with radar and instruments. That plan met considerable resistance from air safety experts who point out that existing air traffic control radar is not accurate enough to ensure safety margins at such close quarters.

John O’Brien, director of engineering and air safety in the pilots’ union, stressed that he does not regard the test as it is now designed to be unsafe, but added that it does imply lower safety margins.

“Sure, you are increasing the potential for two airplanes to get closer together than you would want,” he said.

Safety experts like O’Brien are less concerned about the current test than some techniques the airline industry originally wanted to try or may propose in the future. The industry had proposed even less separation and wanted to conduct the tests in bad weather.

“Some of the things being proposed are really off the wall and we would never accept them,” O’Brien said. “We will accept no technique unless we feel there is an adequate margin of safety.”

Most Congested in U.S.

The air space in the Los Angeles Basin is the most congested in the United States, and flight operating procedures at L.A. International already have generated significant discontent among pilots and air safety experts. Air traffic at L.A. International, officials say, is expected to increase between 5% and 8% this year.

L.A. International is the only major U.S. airport to receive the “black star” rating for safety problems from the pilots’ association. The black star was given in 1975 when the FAA decided to permit aircraft simultaneously to take off toward the Pacific Ocean and land from the same direction at night and in bad weather.

“One of the reasons the FAA went to LAX for this test--I don’t want to say it is a worst-case situation--but if the concept works there it will probably work anywhere,” O’Brien said.

Two Concerns Expressed

While the union agreed to carry out the flights, it also expressed two safety concerns to the FAA. One was that turbulence created by one jet, known as “wake vortex,” could disrupt a jet following as close as 2 1/2 miles.

John Galipault, director of the Aviation Safety Institute, said the possibility of wake vortex near a runway can lead to unpredictable results.

“You may conceivably lose some control at these low speeds near a runway,” he said. “I am concerned about it and others are as well.”

The FAA test excludes large aircraft, such as the 747, DC-10 and L-1011, that create such large wakes that they could indeed destabilize smaller aircraft, such as a DC-9 or 727.

Crowded Runways

The pilots’ union also expressed concern over the potential for so-called “dual runway occupancy,” which means that while one jetliner is taxiing on a runway, a following jet is landing. Such maneuvers are done in the military, but are considered hazardous in civil aviation.

So far, the L.A. International tests have resulted in no reports of dual runway occupancy or encounters with wake vortex, said Ray Robison, assistant air traffic manager at the airport. Robison said that in the first three weeks of the test, 70 aircraft were brought to 2 1/2-mile separation. The plan is to test 2,000 aircraft.

In addition to the tests at Los Angeles, the FAA is looking at reducing separation and other safety margins at other airports in ways that are encountering stiff resistance.

Instrument Landings

For example, the airline industry wants to consider “triple IFR” (instrument flight rules) landings, in which two aircraft may land simultaneously on parallel runways while a third plane lands on a diagonal runway crossing the other two. This would be done using radar and instruments.

“That is simply scary,” Galipault said. “What would happen if communications went down?”

Another technique under consideration is so-called “converging parallel approaches,” in which the lateral separation of planes is reduced to several thousand feet using instrument and radar guidance.

30 Problem Airports

The efforts grew out of the Industry Task Force on Airport Capacity Improvement and Delay Reduction, which was spurred by a lack of adequate airport capacity in the United States at a time when new airports are not being built. The FAA has identified 30 airports as key problem areas.

“We will not get new airports built, but we are getting more traffic,” said Ed Krupinski of the pilots’ union. “We have to find new ways of using our existing capacity without reducing safety.”