Poor piloting, airline training that was deficient and the absence of safety zones beyond the runways at Midway Airport created an atmosphere ripe for disaster, federal officials said Tuesday in determining the cause of a Southwest Airlines accident on a snowy airstrip in Chicago two years ago.
The disturbing findings by the National Transportation Safety Board indicate a systemic collapse of safety. And the investigation provides little comfort for air passengers as winter approaches and commercial pilots call for more reliable information from their airlines, airports and the Federal Aviation Administration about how to operate on slick runways.
At the end of a daylong hearing, the NTSB called on the FAA to tighten airlines’ operating procedures, particularly involving aircraft braking action in bad weather.
The well-experienced pilots of the Southwest jet that skidded off the end of the icy runway at Midway on Dec. 8, 2005, failed to safely slow the plane because they were unfamiliar with a new braking procedure being used for the first time as they attempted to land in a swirling snowstorm, the safety board reported.
The pilots’ lack of experience with the Boeing 737’s auto-braking system distracted them from engaging the aircraft’s engine thrust-reversers until just before the plane rolled off the runway, crashed through two fences and struck vehicles outside the airport on Central Avenue and 55th Street, the safety board concluded.
Joshua Woods, 6, of Leroy, Ind., was crushed to death inside a car, and about 20 people on board the plane suffered minor injuries in the worst accident in Southwest’s history.
While the investigation found that much of the responsibility rested with the pilots, the safety board said Southwest contributed to the tragedy by failing to provide its pilot corps with “clear and consistent guidance and training” regarding company standards to calculate stopping distances in sloppy runway conditions.
The captain of Southwest flight 1248, en route to Midway from Baltimore, likely would have decided to call off the landing and divert to another airport, investigators said based on interviews, if he knew Southwest required using the most conservative rating from the mixed pilot reports they had received on runway conditions at Midway.
Instead, Capt. Bruce Sutherland and First Officer Steven Oliver touched down on a slippery runway 31 Center, which had not been cleaned for almost a half-hour, authorities said.
“This crew knew they were flying on the edge. The problem was they didn’t really know where the edge was,” safety board member Debbie Hersman said in response to investigators’ testimony at the daylong hearing.
Pilots who landed before Flight 1248 rated the condition of 31 Center as being “good” to “fair” on the front end of the runway and “poor” on the second half of the 6,522-foot-long runway, investigators said. One Southwest flight crew flying to Midway decided to divert to another airport nine minutes before the accident.
Southwest’s pilots manual requires pilots to always use the lower assessment — in this case, “poor” — in making stopping-distance calculations that are used to decide whether it’s safe to land. But many Southwest pilots, including Sutherland and Oliver were unfamiliar with that rule.
In addition, Southwest allows no more than a 5-knot tailwind in poor runway conditions. But a right quartering tailwind of 8 knots buffeted the plane when it touched down as the snowstorm intensified, authorities said.
“Southwest policy would require the crew to divert, but they were unaware of the policy. Other pilots were also unaware of the policy,” said Katherine Lemos, a human performance expert with the safety board.
The airline subsequently improved its flight crew training and revised cockpit manuals to ensure pilots are versed in the runway safety policy, officials said.
“This was an extraordinary circumstance that we have learned from,” Southwest spokeswoman Beth Harbin said after the safety board issued its findings.
Southwest Capt. Carl Kuwitzky, president of the Southwest Airlines Pilots’ Association, blamed the accident on “the lack of clarity that was out there.”
As Flight 1248 approached Chicago, the onboard computer calculated a stopping margin of 560 feet would remain after the plane came to a complete stop, based on a “fair” rating of the runway.
If a “poor” rating had been used, however, the computer would have produced a margin of only 40 feet, investigators said.
Because the pilots failed to comply with Southwest policy by plugging the fair condition, the onboard flight computer, issued a recommendation saying it was OK to land, the safety board said.
The pilots also did not know that the computer’s calculated stopping distance assumed the use of engine thrust-reversers, creating an even thinner margin between either successfully stopping the plane on the runway or running off the pavement.
The plane’s thrust-reversers, which help slow an aircraft during landings, activated about 15 seconds too late, when the plane already reached the far end of the runway, the investigation found. The thrust-reversers should have deployed within 3 seconds of the plane’s wheels hitting the ground.
Investigators said the pilots’ unfamiliarity with using the auto-brakes distracted them and contributed to the delay in activating the reversers.
In addition, conditions analyzed after the Boeing 737 overran the runway and barreled onto the street found that the braking conditions on 31 Center were worse than poor, actually rating “nil,” investigators said.
After the Southwest accident, the Chicago Department of Aviation began building safety zones, made up of crushable concrete beds to stop any plane that might overshoot Midway’s relatively short runways. One so-called aircraft arrester bed was built last year, a second is scheduled for completion next week and the final two will be ready by the end of the year, said city Aviation Commissioner Nuria Fernandez.
The FAA, meanwhile, has urged airlines to add an extra 15 percent margin to stopping-distance calculations to ensure that planes can stop safely in bad weather conditions.
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