"I would like to start my Editorial thanking the Chair of USA National Transportation Safety Board Honorable Deborah Hersman for kindly allowing me to use parts of her Statement in the final report for the loss of control accident with Colgan Air.
On 12 February 2009, a Bombardier DHC-8-400, operated by Colgan Air as part of codeshare agreement with Continental Airlines, was on an ILS approach to the Buffalo-Niagara in night VMC when control was lost and the aircraft crashed and burned in a residential area approximately 5 nm from the runway killing all occupants and one additional person on the ground.
The investigation was carried-out by NTSB, 46 findings were recorded, a probable cause was determined as "the captain's inappropriate response to the activation of the stick shaker, which led to an aerodynamic stall from which the airplane did not recover" Additionally, four contributors were listed.
Fatigue was not listed as part of the probable cause but one of the findings reads "The pilots' performance was likely impaired because of fatigue, but the extent of their impairment and the degree to which it contributed to the performance deficiencies that occurred during the flight cannot be conclusively determined".
Both pilots were commuting to their base of Newark. The first officer flew from Seattle to Memphis in a spare seat on one FedEx jet, and to Newark on another. The first officer was reported to have slept 3.5 hours on the flights and 5.5 hours in the crew room. The Captain commuted from his home in Tampa area, Florida, stayed overnight in the crew room with actual sleep unknown and with some potential accumulated sleep lost from previous days. Both pilots can be heard yawning on the cockpit voice recorder. The First Officer can be heard saying 'oh I'm ready to be in the hotel room' and a little bit later 'well this is one of those times that if I felt like this when I was at home there's no way I would have come all the way out here. but now that I'm out here'
During the Board's proceedings, the Chair of NTSB proposed adding fatigue as a fifth contributing factor but the members of the Board rejected the proposal. In her statement in the report, a parallel was made with the impairment effect of alcohol. Today, this impairing effect is well understood and accepted but this has not always been the case. In 1967, the NTSB investigated a collision between a car travelling the wrong way on the highway and a bus which had resulted in 20 fatalities and 11 injuries. They calculated that, at the time of the collision, the driver of the car had a blood-alcohol level of between .15 and .19 (or higher). Nonetheless, their accident report stated that "there is a difference between being 'under the influence' of alcohol and varying degrees of drunkenness". The report went on to determine that the driver was not "drunk" because, prior to the accident, he had successfully travelled around town by car, talked with friends and "therefore, it is logical to believe that he was able to read, comprehend and respond to traffic control devices, although probably not as well or as quickly as if he were sober." In the report, alcohol was not cited as one of the probable cause factors; it was listed as a contributing factor. The Safety Board concluded that because the driver was not immobilised by the alcohol, alcohol was not a causal factor.
Today, fortunately, we do not have anymore arguments like this. The society has placed strict limits on the alcohol use in transportation and none is anymore fascinated to discuss if it is a cause, a contributor, a factor…We have just put an effort to manage it. Now, let us come back to the title of this Editorial. The health warning message on tobacco boxes often reads "Smoking kills", or "Smoking causes cancer". Is this true? You may know someone who smoked all their lives but lived happily in good health till old age. Or, alternatively, you may know someone who never smoked but got cancer anyway. Does this mean that smoking doesn't really cause cancer? By no means! Years of work by the researchers has proven that smoking causes cancer. This doesn't mean that all smokers will definitely get cancer. Neither does it mean that all non-smokers won't. It means that smoking largely increases the risk of cancer. Smokers are, on average, much more likely to get cancer than non-smokers. Fatigue, like alcohol and smoking, seriously affects us. You will learn by reading this edition of HindSight that there are studies which formally compare the effects of alcohol and fatigue on our performance. This, as with smoking, does not mean that if you are fatigued you will have an accident. By this some formal theoretical tests for causality may not be met. But even in the theory, there is no firm agreement on a definition of what cause includes.
It may be time for us to stop arguing how much of a 'cause' fatigue is and instead use the effort to manage it proactively!
And, to give credit to NTSB, in their list of recommendations for the Colgan air accident there is one addressing the fatigue risk. This is what really matters at the end, no matter how we formulate the explanations for the causes. "
Fuente: SKYBRARY
