A blowing snowstorm, a tail wind pushing their plane faster toward Midway Airport and a short runway that became progressively slicker all worked against the pilots of Southwest Airlines Flight 1248, federal investigators said Friday.
More Top Picks Bic Flex 5 Titanium Disposable
The plane, carrying 98 passengers and five crew members to Chicago from Baltimore Thursday evening, experienced a slight bounce after touching down at 143 m.p.h., using up precious runway space as the wheels made contact for a second time with the ground.
The slippery end of the runway–which was “like being on ice skates,” an official for a pilots’ group said–and a steel wall just beyond where the concrete ended, made matters much worse.
Runway braking power was rated only fair as the plane landed on the front portion of the 6,522-foot runway, which was covered by 1/16th of an inch of snow, according to the Chicago Department of Aviation.
But traction deteriorated to poor toward the end of the runway as the pilot tried to bring the Boeing 737-700 to a safe stop, said Ellen Engleman Conners, a member of the National Transportation Safety Board.
The aircraft barreled through a barrier fence at 45 m.p.h., knocking out radar equipment and striking several vehicles on Central Avenue near 55th Street northwest of the airport. A 6-year-old boy in one of the cars was killed, and at least 10 people were injured. The roof of one car was crushed beneath a wing.
Inquiry could take year
On Friday, investigators began assembling thousands of bits of data–ranging from radio communications between the pilots and air-traffic controllers to the mechanical functions of the aircraft–to model the flight and determine what went wrong. That could take about a year, Engleman Conners said.
Chicago Deputy Aviation Commissioner Erin O’Donnell, who manages Midway, contradicted safety board officials, saying the braking action on the runway was “good prior to this incident, as well as after.”
But city officials also said the runway was idle for several minutes before the Southwest plane attempted to land–enough time for the runway to get more slippery. Pilots preparing to land rely heavily on the braking reports of pilots landing in front of them.
Part of the investigation will look at whether the city should have closed the airport, officials said. Midway received 9.3 inches of snow Thursday. Only one runway was open during the storm. Airport crews operating snowplows, power brooms and de-icing equipment worked feverishly to maintain braking action on the runway.
“This is the city of Chicago. Weather is a big factor,” Engleman Conners said.
Only 82 feet separate the end of the runway and the barrier wall–less than one-tenth of the 1,000-foot runway safety area called for in Federal Aviation Administration standards aimed at safeguarding planes if pilots overshoot runways or run off the end of them.
“Airports should continually strive to reach these standards,” said FAA spokesman Tony Molinaro.
Midway can operate with such a small overrun zone because the 77-year-old airport qualifies for a grandfather clause under old rules. The FAA has targeted two of Midway’s runways for safety improvements, but Chicago has not committed to any changes. In fact, the city can seek an exemption to a new law that President Bush signed this week mandating at least 1,000 feet at the end of all runways at major commercial airports by 2015.
Midway “has had a wonderful record of safety,” said Mayor Richard Daley, who recently completed an almost $1 billion renovation of Midway terminals while leaving the landlocked airfield unchanged.
The city operates a voluntary land-acquisition program to buy commercial properties on the perimeter of the airport and landscape them as part of a beautification program, said Wendy Abrams, spokeswoman for the Chicago Department of Aviation. Asked if any of the parcels would be used to broaden the runway safety areas, Abrams said, “Not at this time.”
Clearing the crash site
Meanwhile, investigators said they planned to put the forward section of the plane, from which the nose landing gear was severed when it burst through the barrier, into a sling on Saturday and tow the aircraft back onto airport property to continue an examination of the exterior and passenger cabin.
The plan included reopening the Central-55th Street intersection to traffic no later than Sunday and reopening Runway 31 Center, where the plane landed.
The voice and flight data recorders from the plane were sent to the safety board’s laboratory in Washington Friday. The quality of the information downloaded was “pristine,” Engleman Conners said.
Investigators will also interview the pilots and flight attendants aboard the plane, air-traffic controllers and Southwest Airlines flight dispatchers who provided weather reports to the pilots. Investigators declined to say whether the captain, described only as a 10-year Southwest veteran, or the first officer, who had been with the airline less than three years, was flying the plane.
But the decision to attempt the tricky landing at Midway, after the plane flew at least one go-around over the airport to give the pilots a feel for the wind and low visibility, was made by the captain.
Conversations on the flight deck downloaded from the cockpit voice recorder showed that the plane made a normal approach to Midway, Engleman Conners said. But a slight wind blowing from the east, buffeting the right side of the plane’s tail section, pushed the aircraft faster toward the airport.
When possible, planes land into the wind to help reduce speed. But Thursday night, planes bound for Midway were landing with a tail wind to avoid an airspace conflict with planes on approach and departure routes at O’Hare International Airport, according to controllers at both airports. It is a normal practice that does not become a safety issue except in poor weather.
In addition, the sideways direction of the wind may have required repeated pilot corrections to keep the nose of Flight 1248 aligned with the runway, according to a Midway air-traffic controller who was working in the airport tower the day of the accident.
More Top Picks Best Cookware Set
`Like being on ice skates’
Once on the ground, the real battle to control the airplane began.
In slick or icy weather, the braking power on the first several thousand feet of a runway, where planes touch down, is generally the best due to tire compression against the pavement that keeps the surface de-iced and warm. But stopping power and traction erode quickly by the middle of the runway and diminish even more at the opposite end, which most planes don’t reach because they exit onto a taxiway, experts said.
“At that point, it’s sort of like being on ice skates,” said Gary Boettcher, president of the Coalition of Airline Pilots Associations, a trade group that represents Southwest pilots in Congress.
Boettcher, a 32-year veteran captain at American Airlines, said the FAA issues broad guidelines to airports about closing runways, and each airline has its own policy.
“At American Airlines, if we have a tail wind and braking action is less than good, we are prohibited from landing,” he said.
Gary Kelly, chief executive officer at Southwest, said Flight 1248 “was cleared for landing, and all we can assume is that the runway was prepared for it. … We let our flight crews make a determination as to the braking of the aircraft.”
In a similar incident in 2000–Southwest’s first major accident–a plane skidded off the runway in Burbank, Calif., but did not kill anyone. The captain was among 43 people injured.
Kelly said Thursday, which marked the first fatal accident in the low-cost airline’s history, was “a sad day for Southwest.”
———-