What's Classified As Error Could Be Avoidable Fatigue

By ANN Contributor Steven R. Lund

Assigning "Pilot Error" as the sole cause or even a contributing factor to the cause of an airliner accident is, to say the least, counterproductive. This is tantamount to declaring that Sir Isaac Newton and Albert Einstein contributed to the cause because they formulated classic laws of gravity! Obviously such a "relatively general" reason for an accident has little meaning to facilitate any remedial action to prevent future accidents. So, if any human error was suspected in the chain of events leading to an accident, the most important aspects of this fact is who committed the error, and, most importantly, why was the error committed? Only after these determinations, can investigators formulate effective corrective action. For instance, was the human properly trained to perform the task required? Or, were the proper tools provided, was the human physically capable, or medically fit?

I suspect that some accidents attributed to pilot error were actually simply the result of the pilot being too fatigued to properly perform the tasks required to prevent the accident! I know of one DC-8 freighter accident where "pilot fatigue" was implicated as the cause of the airplane wing stalling and crashing a quarter-mile short of the runway. The wording of the official probable cause was summarized in some news accounts as "pilot error!"

Experts from NASA collaborated with NTSB investigators in assessing whether fatigue was present in the 1993 crash of a US DC-8 (file photo of type, above) freighter in Guantanamo Bay, Cuba. The DC-8 crashed into level terrain during a circling approach to the landing runway in clear weather, resulting in the aircraft being damaged beyond repair, but, no fatalities to the three crew members -- the only persons aboard. The NTSB implicated fatigue as a probable cause-the first time fatigue had been so identified in an aviation accident. Three core physiological factors related to fatigue were identified (cumulative sleep loss, continuous hours of wakefulness, and circadian time of day). All three crewmembers were found to be heavily influenced by these fatigue factors.

There have been other accidents with causes I suspect could have been similarly associated with pilot fatigue, namely:

The June 1999 fatal runway accident of American Airlines Flight 1420 in which a McDonnell Douglas MD-82 (file photo of type, above) overran the end of the runway, went down an embankment, and impacted approach light structures after landing at the Adams Field Airport in Little Rock, AR. Thunderstorms and heavy rain were reported in the area at the time of the accident. There were 11 fatalities, including the aircraft captain, and numerous injuries among the 145 passengers and crew aboard the flight.  The official cause of this accident was "the flight crew's failure to discontinue the approach when severe thunderstorms and their associated hazards to flight operations had moved into the airport area and the flight crew's failure to ensure that the spoilers had extended after touchdown. Contributing to the accident were the flight crew's (1) impaired performance resulting from fatigue and the situational stress associated with the intent to land under the circumstances, (2) continuation of the approach to a landing when the company's maximum crosswind component was exceeded, and (3) use of reverse thrust greater than 1.3 engine pressure ratio after landing."

Even though the weather was a factor in this accident, there was no wind shear present. But there were crosswinds compounding the difficulties faced by the pilot in performing the approach and landing and the fact that pilot fatigue was deemed a "contributing factor to the accident tends to amplify the Pilot Error cause due to the official report listing a number of failures both before and after the plane's touchdown on the runway.

The crash of KAL Flight 801 in Guam on August 6, 1997 (above), was the result of several errors by the crew, most notably a lack of situational awareness resulting in "controlled flight into terrain (CFIT)." However, the pilot in command of the flight was a senior and experienced pilot in the company. While the captain was not familiar with the terrain, and visibility at the time was reduced due to rain, the approach into Guam should not have been difficult. So what caused the Captain to lose concentration and situational awareness, and thereby fly a perfectly good 747 into a hilltop, killing 228 people? Could it be that prior to flying to Guam he had flown from Seoul to Australia, back to Seoul, to Hong Kong, and then back to Seoul again before his fateful trip to Guam, all with only a few hours of rest?

The official probable cause of this accident was "The captain's failure to adequately brief and execute the nonprecision approach and the first officer's and flight engineer's failure to effectively monitor and cross-check the captain's execution of the approach. Contributing to these failures were the captain's fatigue and Korean Air's inadequate flight crew training. Contributing to the accident was the Federal Aviation Administration's intentional inhibition of the minimum safe altitude warning system and the agency's failure to adequately to manage the system." Again, a list of human failures without specific mention of why! It's no wonder that this accident could be relegated to the "Pilot Error File" without meaningful remedial action and the very predictable non-zero probability of repeat accidents.
 
Going back a bit to March 1969 when a United Arab Airlines, Russian built Ilyushin 18 tried to land at Aswan, Egypt after 2 previous attempts in a sandstorm. Rising sand in the Aswan area caused the visibility to drop from 10km to 2-3km. The right wing contacted the left side of the runway 1120m from the threshold. The wing broke off and the aircraft crashed in flames killing 100 passengers and crew of the 105 total persons aboard.

The official cause of this accident was: "Pilot descended below the minimum safe altitude without having the runway lights clearly in sight. A contributory factor was fatigue arising from continuous working hours without suitable rest periods."

By now it should be obvious that the root cause of these accidents where the human pilot made errors was fatigue, not pilot error! So, what can be done about fatigue?

(Steven R. Lund is the retired director of flight safety investigations in flight operations for the Douglas Products Division of the Boeing Commercial Airplane Group in Long Beach, California. He has spent over 36 years in the US aerospace industry, the last 32 of which have been at the Douglas Aircraft Company (now Boeing). His entire career at Douglas/Boeing has been devoted to flight test, flight safety, and commercial jet transport incident and accident investigation. Steve has some very definite thoughts on that question -- and we'll share them in tomorrow's edition of Aero-News. -- ed.)

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