Is reducing risk always worth the price?

A 2008 academic study showed that changing the configuration of the runways of Los Angeles International Airport’s North Airfield would reduce the number of deaths caused by runway accidents. But the panel’s recommendation of what to do about that surprised just about everyone.

MIT Sloan Professor Arnold Barnett chaired the panel, which included faculty from the University of Maryland, George Mason University, Berkeley, MIT, and Virginia Tech. Barnett gave MIT Sloan alumni the inside story of the study, the panel’s conclusion, and the public reaction during his Alumni Weekend 2011 workshop, “Mortality Risks.”

The academic study was the sixth study done to consider widening the space between the runway used for takeoffs and the runway used for landings, as well as how landing airplanes crossed the takeoff runway to reach the terminals. In 2005, then-candidate for mayor of Los Angeles Antonio Villeraigosa campaigned that he would only consider reconfiguring the runways for safety reasons. The five previous studies all recommended that moving the runways would improve safety, but neighboring communities all opposed the effort to change the runways.

Villeraigosa won the election and the sixth study was commissioned. Barnett’s panel looked at three options: leaving the runways as is with the landing plane crossing the takeoff runway at an acute angle, moving them 100 feet farther apart and adding a third center taxiway that would enable the landing plane to cross the takeoff runway at a 90 degree angle, and moving them 340 feet farther apart and adding the center taxiway.

Using actual pilots and controllers, the panel did simulations and came to the conclusion that LAX’s north airfield was extremely safe under the current configuration with the risk of a passenger death caused by a runway collision being 1 in 150 million. But, separating the runways by 100 feet would reduce that mortality rate by 40 percent, and separating the runways by 340 feet lowered the mortality risk by 55 percent.

The panel’s conclusion? Don’t bother.

“If a number is incredibly small, reducing it even by 50 percent might not mean that much,” Barnett says.

In the last decade, 750 million passengers flew in or out of LAX. During that time there were five deaths caused by runway accidents and 75 deaths by other accidents, for a total of 80 deaths. Reducing the number of runway accident deaths by 40 percent lowers the actual number to 3 deaths, which, added to the 75 deaths by other accidents, brings total deaths to 78. Thus, the runway reconfiguration would save two lives in a decade.

“If it costs a billion dollars you might say, ‘Might we not be able to spend a billion dollars in ways that might save more lives?” he says, suggesting improving highways or funding cancer research as possibilities. “In a world of finite resources we have to make choices.

“Air travel has become so safe that attempts to improve it marginally may not pass a cost/benefit test,” Barnett says.

The study was embraced by the neighboring community groups, criticized by supporters of the runway reconfiguration, and has been largely ignored by LAX, Barnett says. Still, the runway configuration remains the same and the debate continues. As for Barnett, he usually flies into Los Angeles through Long Beach Airport anyway, because that’s where his preferred airline lands.

The study can be found at

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