A diversion would have meant as much as another hour of flying. Last month, the Federal Aviation Administration released the transcript of conversations between the Little Rock air traffic controller and the pilots, showing that the pilots continued with the landing despite several warnings of bad weather. The controller warned of visibility of less than 1,600 feet and winds gusting across the runway at 52 mph before the plane was cleared to land, but the pilots continued the approach. Investigators have not been able to determine whether a critical system of wing spoilers was set before landing. When the plane touched down, the spoilers did not automatically pop up as they should have.
Spoilers are flat panels that raise from the top of the wings on touchdown.
They disrupt the uplifting flow of air over the wings, allowing the full weight of the plane to settle on the landing gear. Without the spoilers, experts have said, the jetliner probably stood little chance of staying on the runway. Late last week, safety board officials received preliminary information from experts at the Massachusetts Institute of Technology suggesting that Flight 1420 was rocked by a powerful wind shear known as a microburst just as the jetliner touched down. Safety board officials are reviewing weather radar data, but sources close to the investigation said Tuesday that the microburst probably occurred as far as two miles from the airport. A microburst is a wind downburst that creates a powerful turbulence not unlike the spray of a garden hose aimed directly at the ground.