Is Dallas Runway Design a Fit for O'Hare?

The FAA said it is working with controllers and the airlines to implement safe procedures at the expanded O'Hare to deal with the increase in runway crossings. One proposal would require planes to taxi behind aircraft sitting on a runway rather than in front whenever possible.

"Perimeter taxiways are a good idea, and whenever it is possible, we should do it," said Barry Cooper, a top FAA manager who headed the team that approved O'Hare expansion. "Unfortunately, we don't have the real estate to do it at O'Hare."

Three serious near-collisions on runways in Boston, New York and Las Vegas this year prompted the National Transportation Safety Board on Nov. 15 to again press for quicker action by the FAA to reduce such dangers.

There were 326 runway incursions nationwide in fiscal 2004 and 324 in fiscal 2005, according to the FAA.

Parallel runways, as opposed to the intersecting-runway pattern at O'Hare, allow more airplanes to land each hour, especially when visibility is reduced. But if the airport footprint is not large enough to allow widely spaced parallel runways, which ensure that low-flying planes are kept safely apart, the only solution for air-traffic controllers is to slow down the rate of departing flights to avoid interference with arrivals.

The worldwide trend is to build new airports on large expanses of land to allow planes to safely touch down and take off simultaneously, even in bad weather. Large tracts of land also buffer surrounding populations from jet noise.

DFW covers 18,000 acres. O'Hare would grow from 6,789 acres to 7,222 acres under Chicago's runway-expansion plan, which depends on taking 433 acres from surrounding communities.

Denver International Airport is situated on 34,000 acres. Kansas City International Airport takes up more than 10,000 acres, with at least 7,000 additional acres available to develop. The proposed south suburban airport near Peotone in Will County would sprawl over almost 20,000 acres.

But Chicago officials point to Atlanta's Hartsfield-Jackson International Airport, where four parallel runways are squeezed onto fewer than 5,000 acres, as another model for the future O'Hare.

"Size isn't everything," Andolino said. "Atlanta is smaller than O'Hare, and it will handle more flights and more passengers than O'Hare this year."

But Hartsfield is far from a top performer in the category that matters most to passengers--arriving on time. Of the nation's 33 largest airports, Atlanta ranked 28th for on-time arrivals from January through September this year, according to the U.S. Department of Transportation. Even O'Hare, with its crisscrossing runways, did better, finishing 25th.

DFW ranked sixth with 81 percent of flights arriving on time.

Size helps.

"I don't think Boeing builds enough airplanes to create a capacity crunch at DFW," said JoEllen Casilio, FAA air-traffic control district manager for airports in the Dallas region.

More than a mile separates many of Dallas' runways, allowing simultaneous landings and takeoffs even in intense fog.

But at the expanded O'Hare, the runway separation will be so tight that flights will have to be staggered under some conditions, diminishing efficiency.

Two pairs of runways nearest to the passenger terminal complex would be only 1,200 feet apart. Air-traffic controllers must treat parallel runways that are less than 2,500 feet apart as a single runway, meaning takeoffs and landings cannot be conducted simultaneously.

Controllers in O'Hare's air-traffic tower are concerned about accidents occurring if a plane landing were to stray or be pushed by strong winds from its designated approach path. Turbulence from large planes taking off on the adjacent runway could also spell trouble.

The perimeter taxiways planned at DFW will produce a 30 percent gain in flight capacity, according to real-life simulations conducted with NASA, airline pilots and air-traffic controllers.

"It's the gift that keeps on giving. The pilots love the simplified movement of aircraft on the airfield, and the controllers especially love it," said Jim Crites, executive vice president of operations at DFW.

He said the perimeter taxiway plan will cost $280 million for the entire airport--a bargain in the world of airport capital improvements. The project will be done in phases, with construction starting next year or 2007.