Fatigue Still Not Ruled Out in San Francisco ACA759 Close Call

By Clinton Marquardt - Sleep & Fatigue Specialist

August 30, 2017

fatigue and accidents, fatigue and aviation, fatigue factor

Earlier this month the NTSB released an update into their investigation of the Airbus A320 that squeezed through a potential disaster by less than 59 feet. I finally found time to read through the update and it looks like the NTSB is sticking to their protocol of only releasing validated factual information. This is a good thing; it is still way too early to thoroughly identify all the causal factors. Plus, dropping hints at what they are considering would result in too much conjecture and a knee jerk reaction to stick together a patchwork of solutions.

In the NTSB update, there were two facts that lead me to believe they have not yet ruled out fatigue and that they are following a methodologically strong investigative process similar to mine. The first step in the process I follow is to determine the likelihood that the operators were fatigued. The second step is to ask, “so what?”. Just because we are fatigued, it doesn’t mean that whatever performance impairments we display will be guaranteed to result in an accident. This is one of the reasons why it can be challenging to persuade decision makers to take action….fatigued people don’t always crash. But their performance does suffer. The answer to “so what?” is, if the performance impairments demonstrated by the operators were consistent with what you would expect from a fatigued person, AND they played a role in the accident, then fatigue was a causal factor.

The NTSB is probably following a similar investigation method, first looking at whether the pilots may have been fatigued and then trying to figure out if any fatigue related performance impairments played a role in the incident.

What tells me that they are looking into fatigue is that they said that the pilots were Toronto based. This means that, if their circadian rhythms were nicely synchronized to Toronto time, and they normally slept at night, then they were trying to land during their circadian trough, a period of high fatigue.

The second interesting fact was that the NTSB said that the pilots stated “something did not look right to them”. This could be an example of a delayed reaction time. I have seen this before, where an operator has a feeling that something is not right, but they don’t know exactly what is not right. This could be because their brain is taking longer than normal to process the information and allow the operator to react and it happens to fatigued people. This could mean that the NTSB is looking into fatigue related performance impairments.

I am sure there will be a lot more to come for this investigation. If you want to follow along with the NTSB, here’s the link: https://ntsb.gov/investigations/Pages/DCA17IA148.aspx

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