Sunday, November 04, 2012

Decision Making - Bias

 Essence of decision making whether one is a pilot, air traffic controller, or aircraft mechanic is:
  1. Having the proper information at hand and,
  2. being able to make the proper decision based on that information.
1. Having the proper information at hand

"A decision is thus no better than the information it is based on."

Could Chalk Airlines accident (N2969 killing all 20 people aboard) been prevented if better information were present? How many times have mechanics found the manufacturer's service department is "non- existent" or provides  little information? Is the method of delivering critical information to the mechanic effective? "It's up to the  mechanic" attitude toward service information doesn't lead to an effective solution nor enhance safety. Many times this is an organizational problem and responsibility.

Chalk Airlines mechanic's decisions, while with hindsight are fatally flawed, might not have been an incorrect decision based on the information present at the time. Throw in a dose of confirmation bias and the decision even becomes expected under the circumstances. This leads one to the conclusion that accidents such as this one are not a one-off event.

2. Being able to make the proper decision based on that information

Confirmation Bias recognition and management

We can have a lively discussion about what decision to make even when all relevant information is present. I don't understand why you don't agree with me and you don't understand why I don't agree with you. "People believe what they want to believe" This is Confirmation Bias. Interesting accidents caused by Confirmation Bias include Comair Flight 5191, Airbus A321-232 SK-473 and Airbus A320 UP-BWM. A more formal description of Confirmation Bias:

Confirmation bias is a phenomenon wherein decision makers have been shown to actively seek out and assign more weight to evidence that confirms their hypothesis, and ignore or underweight evidence that could disconfirm their hypothesis. As such, it can be thought of as a form of selection bias in collecting evidence.

We all have Confirmation Bias. It's not a defect but normal human behavior. Errors caused by Confirmation Bias are not solved through penalties. For the aircraft mechanic I believe there are two methods of reducing maintenance errors caused by Confirmation Bias:
  1. You cannot inspect your own work. Often you cannot see your own mistakes, even glaring ones, because your mind has already decided that the work was done as you intended. An inspector does not have your bias (he has his own) and can better judge your work.1.
  2. Education and recognizing when Confirmation Bias might be present. 
With 45 years in aviation I have learned that most mistakes (flying or maintenance) are not due to a lack of skill, but a lack of judgment. How often have I been told that "he is a good pilot". Fine, that's good, but as a human being can he make the right decision when the situation gets rough? For that we need to look at the soul of the person; the personality. Can he accept failure (land before his destination)? Or will his ego send him forward on a path of destruction?  Its not about being good -- its about avoiding failure. Sometimes the more timid pilot is better at avoiding failure.

Part II Irrational Positive Bias in Aircraft Maintenance

Further Reading:

Metal Fatigue, Cracks, and Turbo Mallards
Cracks in Aircraft Structures

1. Who made the mistake? The mechanic who didn't do the job properly? The inspector who failed to notice the mistake? or the employer who failed to provide an inspector?

Confirmation Bias in Reading
Sometimes we read what we expect to read and not what is written. Did you notice the extra THE above?

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