The Southwest Airlines jet that overshot the runway during a snowstorm in Chicago last week needed another 800 feet to safely stop, investigators said in a preliminary report on Thursday.
Flight 1248, a Boeing 737-700, from Baltimore skidded off the runway at Midway Airport, crashed through a blast fence and struck cars on a city street, killing a small boy in one of the vehicles.
The National Transportation Safety Board said in an update of its investigation into the December 8 accident that the crew -- with the help of the airline's ground staff and on board computer -- determined the plane carrying 103 people could land despite the snow and a tail wind.
Preliminary calculations show that the aircraft's wheels hit the snow-covered ground about a third of the way down the runway -- with approximately 4,500 feet remaining -- at 245 kph.
Investigators said the plane would have needed another 800 feet to stop based on how the crew handled the engine thrust reversers and brakes. The jet would have been able to stop on the runway with a little room to spare had it landed into the wind.
The reversers, which slow the plane, were operating and the crew was applying maximum pressure on the brakes manually when the plane ran off the runway at 46 miles per hour (74 kph).
There were no maintenance problems with the engines and the brakes were in good condition, investigators said. The tires were also in good shape. The jet had been delivered to Southwest in 2004.
The captain told investigators he had trouble deploying the thrust reversers immediately after the plane landed. The co-pilot noticed the problem and activated them 18 seconds after touchdown -- or about 14 seconds before the jet crashed through the fence at the end of the runway.
Investigators said last week they were looking closely at the thrust reverser system and whether they were deployed in time.
Prior to takeoff from Baltimore, the runway assignment at Midway for Flight 1248 was switched to Runway 31C, which has a more forgiving approach path in bad weather. Runway 31C was the only one open at the time of the accident.
The crew said the flight from takeoff to touchdown was normal.
