Pilot fatigue, error probable causes of '99 Little Rock crash

The plane's captain and 10 passengers were killed in the 1999 crash of American Airlines Flight 1420.

From Beth Lewandowski
CNN Washington Bureau

WASHINGTON (CNN) -- Distracted by rapidly deteriorating weather conditions and fatigued by a long work day, the flight crew of American Airlines Flight 1420, which crashed at the Little Rock Airport in June 1999, forgot to turn on the automatic spoiler system that would have stopped the plane before it ran out of runway, federal investigators have concluded.

"I believe fatigue was a significant factor in this accident," Evan Byrne told National Transportation Safety Board members at a public hearing Tuesday to review the agency's final report on the crash. The captain and 10 passengers were killed, and more than 100 others were injured.

At the time of the accident, which occurred at nearly midnight during severe thunderstorms, the captain and first officer had been awake for nearly 16 hours and on duty for about 13 hours. The Federal Aviation Administration has imposed an eight-hour limit for a pilot's flight time during a 24-hour period.

The long work day could have led to the flight crew's failure to perform the task of deploying the spoiler system, which is a standard item on their pre-landing checklist. But investigators could not say with 100 percent certainty that fatigue was the cause because there were no tests that can definitely show the effects of fatigue on pilot performance.

"The investigation determined that the flight crew did not arm the automatic spoiler system before landing or manually deploy the spoilers after touchdown," lead investigator Thomas Haueter told the NTSB panel.

"Spoiler deployment is crucial to optimal landing performance because the spoilers increase drag and decrease lift," he explained.

Spoiler panels, found on the wings of aircraft, supplement the braking system to slow a plane down when landing.

Additional tests done by NTSB investigator John O'Callaghan indicated that if the spoilers had been deployed on the aircraft during the crash, it would not have overrun the runway even though it was wet and crosswinds were reaching dangerous levels.

"This is one we never could have heard about," another investigator, John Clark, said, noting that aircraft landings in thunderstorms are common and that this plane could easily have landed with the spoilers on.

Nonetheless, the accident report criticized the flight crew's decision to continue the plane's approach to the airport despite the severe thunderstorms that were rolling into the area.

Although investigators concluded that the flight crew members could have reasonably expected to land safely in the thunderstorm during the descent and final approach when the first officer was able to maintain visual contact with the runway, they "should have recognized that the approach to runway 4R should not continue because the maximum crosswind component for conducting the landing had been exceeded," the report said.

Investigators said the crosswinds averaged about 20 knots, with gusts up to 40 knots -- too strong to land, according to guidelines set by American Airlines.

The report's safety recommendations include requiring the FAA to install at all air traffic control facilities a near-real-time color weather radar display that shows detailed precipitation intensities. It also calls for a task force to develop more effective strategies to reduce the number of planes landing in thunderstorms and to establish better strategies to aid pilots in decision-making with respect to weather conditions.

Another recommendation directs the FAA to require pilots to establish better procedures to verify that the spoilers have been deployed.

In addition, the Safety Board reiterated recommendations previously made that the FAA establish "within two years scientifically based hours-of-service regulations that set limits on hours of service, provide predictable work and rest schedules, and consider circadian rhythms and human sleep and rest requirements."

Current FAA regulations limit to eight hours a pilot's flight time during a 24-hour period, provided the pilot has had at least eight hours' rest during that same period.

The airline industry, represented by the Air Transport Association and the Regional Airline Association, entered into litigation with the FAA on this rule. As a result, the FAA has not been able to enforce the eight-hour flight time limit although it can still impose civil penalties for violations of the rule.

A final ruling is expected in April 2002.