Runway 35 Left at Denver International Airport looked clear to the pilots of a Frontier Airlines Airbus A319 as they dropped from a 600-foot ceiling of clouds one morning in early January 2007. Blowing snow cut visibility to about a half-mile, so they were flying an instrument approach.
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Then they saw the airplane sitting on the runway, dead ahead. The pilot of the Key Lime Air cargo turboprop had inadvertently followed blue taxiway lights (the centerline lights were obscured by the snow), turning onto a 12,000-foot active runway at the nation’s sixth busiest airport. A puzzled ground controller asked him where he was, just as the Frontier pilots spotted his airplane and yanked the nose of the Airbus up to abort the landing.
A collision alarm sounded in the tower. The two airplanes missed each other by about 50 feet.
Nearly once a day, on average, an airplane or airport vehicle ends up on a U.S. airport runway where it is not supposed to be. Such potentially hazardous incidents are called “runway incursions.” Not all are as dangerous as the close call in Denver—one of at least five instances there since 2000. But according to the Federal Aviation Administration, almost every 10 days an incursion poses the serious chance of a collision. Only last-second reactions by pilots have averted several disasters.
The good news is that there are ways to prevent incursions. More than a decade of research by NASA, the Department of Transportation, and aviation companies shows that cockpit displays, like the moving maps now widely available in automobiles, plus bolder runway striping and lighting at airports, can prevent the most common pilot errors that cause incursions. Basic improvements are now becoming available. But growth in air traffic is making incursion rates rise (incursions more than doubled nationally as air traffic grew between 1994 and 2000), so safety leaders want to pick up the pace.
“We’ve got the technologies; it’s now a question of deciding which of those technologies to use,” says Mark Rosenker, chairman of the National Transportation Safety Board, which began pressing the FAA in the 1970s to step up prevention of runway incursions. “Too many incursions are occurring annually,” Rosenker says. “We’ve been running on luck, and luck is no way to run a national air system.”
The reality is that, until recently, runway incursions were eclipsed by more serious dangers, such as airplanes colliding in the air or flying off course and into the ground (known as “controlled flight into terrain”), says Basil Barimo, vice president of operations and safety for the Air Transport Association, which represents the airline industry. Now that cockpit warning systems have greatly reduced those risks, runway incursions have risen to the top of the safety to-do list.
“You get the biggest risk first and then you work your way down,” Barimo says. “While runway safety is getting a lot of attention now, it’s only because we’ve eliminated, quite frankly, the more significant risks.”
There is no simple solution for runway incursions because there is no single cause. According to federal statistics, more than half happen when pilots make a wrong turn or fail to stop short of a runway; responsibility for the rest is split between air traffic control mistakes and airport workers going astray when towing airplanes or driving trucks.
“It’s sort of hard to crack the code of why this happens,” says former FAA Administrator Jane Garvey, who made runway safety a priority during her term, from 1998 to 2002. “You find an awful lot of human error. Those are always more difficult because they are unique to the individual.”