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Just a Bit Biased

How to See and Avoid Dangerous Assumptions

FAA Safety Briefing
Jun 30 · 8 min read
An abstract drawing of a woman in silhouette.
An abstract drawing of a woman in silhouette.

Bias Defined

If you have ever read up on human factors and human error, you have likely heard a story or two of how a pilot was affected by a cognitive bias. Cognitive biases are mental adaptations that occur when a person’s prior knowledge, or their expected outcome, influence their resulting perceptions, interpretations, and decisions. But not all bias is bad. Biases result from cognitive heuristics, also known as “shortcuts,” that we mentally make to aid in the decision-making process.

Graphic that says Aviation Human Factors.
Graphic that says Aviation Human Factors.

When Bias Goes Bad

Working in the FAA’s Office of Accident Investigation and Prevention, I get to see firsthand how bias can get the better of us. While heuristics are often a good thing and help us navigate life quickly, they become an issue of biases gone bad when they lead to perceptual distortion, such as misidentifying the designated runway/taxiway; inaccurate judgment, such as over/underestimating how close/far convective weather is; distraction, like being too busy chatting with a passenger to effectively monitor flight progress; fixation, like only looking at the cockpit array rather than looking out the window; and complacency, such as assuming a controller will advise you of traffic instead of actively looking for it.
Some of the more common biases that affect pilots are expectation bias, confirmation bias, plan continuation error, automation bias and automaticity.

It’s To Be Expected

Expectation bias is when we have a strong belief or mindset towards something we expect to see or hear, and act according to those beliefs. For example, a pilot contacts the tower and indicates he or she is ready for an intersection take-off. The controller clears the pilot for runway 10, however he or she departs from 28 because that is what the pilot was expecting and where he or she has typically departed from in the past.

Photo of a pilot in the cockpit.
Photo of a pilot in the cockpit.

Some of the more common biases that affect pilots are expectation bias, confirmation bias, plan continuation error, automation bias, and automaticity.

Looking for Confirmation in all the Wrong Places

Next is confirmation bias. This is when we only look for, listen to, or acknowledge information that confirms our own preconceptions. We tend not to seek out or pay attention to evidence that could disconfirm the belief. I see this a lot in visual flight rules (VFR) into instrument meteorological conditions (IMC) incidents and accidents where there is often evidence of the pilot’s natural inclination to look for positive information that will allow them to complete the flight even as they ignore or downplay information that could lead away from achieving that goal.

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What the Heck Is It DOING?

Technological advancements in the cockpit are a wonderful thing, but their use can lead to unintended consequences. Automation bias is when we over-rely on automated aids and decision support systems, or become complacent in assuming the technology is always correct. We subsequently fail to monitor or question the technology sufficiently. As a result, manual flying time dramatically decreases, we can get distracted, and the automated information replaces personal vigilance which leads to complacency. The problem arises when the human is left “out of loop” and no longer knows just what the heck the automation is actually doing when it comes time to step in.

Photo of a portion of a cockpit with a lot of buttons.
Photo of a portion of a cockpit with a lot of buttons.

Yes, Dear

Last, there is automaticity or what I call the “yes, dear” response. I am sure anyone who has a significant other, children, parents, close friends, etc., can relate to what I mean by this.

Photo of runway from cockpit.
Photo of runway from cockpit.

I Get Bias (With a Little Help from My Friends)

One of my favorite quotes of all time is from Douglas Wiegmann and Scott Shappell, two preeminent Human Factors (HF) researchers in the industry and in academia. They said that human beings by their very nature make mistakes; therefore, it is unreasonable to expect error-free human performance. It is a concept that my fellow HF contemporaries and I have taken to heart. For us, understanding how bias is likely to affect pilots helps us see the bigger picture better and helps us to create mitigations that prevent the inevitable human error from becoming an accident.

  1. Make a Backup Plan: Don’t expect the standard strategy to always work. Have alternative plans. Think about what would happen if the “go to” option is no longer available.
  2. Active Listening: Especially when communicating with ATC! Active listening is a way of listening and responding to another person that ensures mutual understanding. It requires each person in the conversation to fully concentrate on and understand the intent of what is being said.
  3. Look for Disconfirming Evidence: Test out your assumptions by trying to actively disprove them.


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This article was originally published in the July/August 2020 issue of FAA Safety Briefing magazine. https://www.faa.gov/news/safety_briefing/
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