Pilots in Chicago Accident Missed Landing Zone, Report Says

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.

The plane hit the runway forcefully with a ground speed of 152 mph, investigators said. The plane bounced and became momentarily airborne again during a 29-second landing attempt.

The Boeing aircraft’s thrust reversers, which help the automatic braking system that the pilots use to stop a plane, were not functional until more than midway through the landing, investigators said.

The delay was much longer than what the safety board previously reported, based on interviews with the pilots two days after the crash, which was the first fatal accident in Southwest’s history.

“The first officer reached over and pulled the thrust reverser switch. He also moved his seat forward to help the captain apply maximum foot-pedal braking,” said Keith Holloway, a spokesman for the safety board.

After slipping off the runway, the plane carrying 98 passengers was slowed when it rolled through a fence designed to absorb jet blasts, an airport perimeter fence and onto the street, where it hit two vehicles. The impact killed Joshua Woods, 6, of Leroy, Ind., who was inside one vehicle with his family on his way to visit his grandmother in Chicago.

From the time the plane landed to when it came to an abrupt, colliding stop, the plane traveled about 5,000 feet, the safety board said.

The stopping distance for a landing would have been about 1,000 feet less if the plane landed into the wind from the other end of the runway, instead of landing with a tailwind that hindered the plane’s ability to stop, the safety board report said.

But a landing into the wind was not an option. The visibility pilots needed to descend in the thick fog from that direction using their instruments did not meet FAA rules, the safety board said.

It remained unclear whether the failure of the thrust reversers was caused by a mechanical problem or pilot error. The safety board is testing the thrust reverser systems.

The captain told investigators that he had trouble moving the lever that activates the thrust reversers, which are supposed to begin working as soon as the plane lands.

In a separate interview, the first officer said he reached over after “a few seconds” and was able to get the lever for the thrust reversers to engage.

But data from the plane’s flight recorder show that the thrust reversers did not activate until about 18 seconds after landing, the safety board said.

The delay meant that the thrust reversers were working to redirect air from the jet engines up and forward for about 14 seconds before the plane hit the blast fence.

Many pilots who have flown into Midway during bad weather have questioned the judgment of the Southwest crew.

The update on the accident from the safety board did not alter their views.