CHICAGO — After deciding it was safe to land in a snowstorm, the pilots of Southwest Airlines Flight 1248 overran the zone where the plane needed to touch down and lost hundreds of feet of runway that would have helped stop the jet before it skidded outside the airport and killed a 6-year-old boy, federal investigators said Thursday.
The plane glided over the runway at Midway International Airport in Chicago, wasting precious stopping distance, before the captain planted the landing-gear wheels more than 2,000 feet beyond the front edge of the 6,522-foot runway. The pilots needed at least 800 more feet of runway to avoid a collision with the barrier at the end, the National Transportation Safety Board reported Thursday, updating the status of its investigation.
As the plane approached the airport Dec. 8, the pilots and a Southwest dispatcher were confident a landing could be accomplished, despite contending with low visibility, a tailwind and reports of poor braking power on snowy Runway 31 Center, they later told investigators.
The pilots based their decision to land on the dispatcher's positive assessment, their piloting experience and flight data they entered into a computer in the cockpit, investigators said. Weather updates indicated that a freezing fog was setting in, but the computer confirmed the difficult landing would be within the capability of the Boeing 737-700 and would conform to Southwest's procedures.
But the 59-year-old captain, who was flying the plane, missed the landing zone, investigators said.
Preliminary calculations, using radar information and the flight data recorder onboard the Boeing 737-700, show that the plane touched down with about 4,500 feet of runway remaining. The aircraft needed about 5,300 feet stopping distance under the slick conditions to avoid hitting obstructions, the report said.
It also was unclear whether it was legal for the Southwest jet to land in the heavy snow.
About 20 minutes before the accident, visibility was half a mile -- less than the three-quarters of a mile of visibility that the Federal Aviation Administration requires for an approach to Runway 31 Center, the safety board's report said. Making a landing with half a mile of visibility would violate FAA regulations.
Air traffic controllers in the Midway tower told investigators they did not see the plane land, but they spotted the aircraft's lights penetrating the snow and ground fog.
