Inadequate Standardization and Tired Pilots Emerge As Top Issues In Crash Investigation

Air Safety Week, Oct 29, 2001

More standardized procedures and policies among carriers and less fatigue among pilots are needed to raise the level of safety in the airline industry. These are the two central "lessons" emerging from a 28-month investigation into a fatal runway overrun accident.

If standardization within one carrier is seen as a major aspect of its safety program, then standardization among carriers, and among various airports respecting their emergency response procedures, could improve safety system- wide. And, right now, there are lapses on both counts.

The case involves the June 1, 1999 crash of an American Airlines [AMR] MD-82 during an attempted landing in a severe thunderstorm at Little Rock, Arkansas. The case triggered a major investigation by the U.S. National Transportation Safety Board (NTSB), not only because it was a fatal accident, but also because it featured a penetration into a fierce thunderstorm, pilot fatigue and failings in basic procedures.

At the NTSB's final hearing last week, highlights of the accident were outlined by investigator-in-charge Tom Haueter:

"Flight 1420 began its descent, approach, and landing to the airport as a line of thunderstorms was moving through the Little Rock area. After landing, the airplane departed the end of the runway, passed through a chain link security fence, went down a rock embankment to a flood plain, which was located approximately 15 feet below the runway elevation, and collided with the structure supporting the runway 22L approach lighting system. The captain and 10 passengers were killed. The first officer, the flight attendants, and 105 passengers received serious or minor injuries, and 24 passengers were not injured. Impact forces and a postcrash fire destroyed the airplane."

The immediate reason the airplane roared off the far end of runway 4 right (4R) was the crew's failure to arm the spoilers prior to landing. Then, in the 26 seconds between touchdown and flight data recorder (FDR) shutoff, there is no indication that the crew took belated action to manually deploy the spoilers.

Up the creek without spoilers

Investigators found that American Airlines' procedures regarding spoiler operation at the time of the accident differed in significant respects from other carriers operating DC-9/MD-80/MD-90 series aircraft. At American, the practice was for the pilot not flying (PNF) to arm the spoilers by moving the handle on the center console to the armed position, and then moving the appropriate switch on the carrier's mechanical landing checklist to indicate that the spoilers have been armed. The process did not require a verbal callout and readback between both pilots, as was the practice at other carriers. Nor was a positive callout of spoiler deployment required at American while, again, this was the practice at other carriers operating the same type of aircraft.

NTSB investigators also found a variance between practices inculcated during simulator training sessions and actual practice "flying the line." In simulator training, the PNF would arm the spoilers, but during actual flight operations where the captain was the pilot flying (PF), the captains often would arm the spoilers (the handle is on the left side of the console). The PNF might not notice, due to the absence of a requirement for positive verbal dual- confirmation of spoilers armed. As David Tew, head of the NTSB's operations group part of the Flight 1420 investigation, observed, the first officer would have to tilt his head to see the red-painted metal portion of the handle to know that the spoilers were armed.

A second incident eight months later, in which another American Airlines jet landed without its spoilers armed on a runway with patches of water from a recent rain at Palm Springs, California, and departed the hard surface during the rollout, prompted the carrier to change its procedures. Those changes were announced just two days after the February 16, 2000 incident at Palm Springs (see ASW, May 28). Flight crews now must verbally confirm arming of the spoilers, and a callout of spoiler deployment after touchdown must be made. These changes effectively bring the carrier's practices into alignment with those at other carriers.

The spoilers on the MD-80 have an enormous impact on stopping distance. By killing lift (hence the term "spoiler"), these devices put more weight on the main landing gear, which greatly increases the effectiveness of braking.

Without spoilers, the Flight 1420 crew was doomed to overrun. They touched down about 2,000 feet from the threshold of the 7,200-foot runway. The captain, as the PF, had elected to use manual brakes, but delayed using them some 11 seconds after touchdown. He made aggressive use of reverse thrust, in fact exceeding the maximum 1.3 engine pressure ratio (EPR) authorized for landing on wet runways - not to mention exceeding the maximum 1.6 EPR for landing on dry runways. In the last-minute effort to maintain control as the airplane swerved down the runway, the right engine recorded a maximum 1.9 EPR, the left engine hit 1.7 EPR.