When talking about aviation safety, it is very important to understand how human factors
play a part. Humans have the biggest impact on aviation safety. Most accidents tend to be caused
by human error, and most accidents can be prevented by maintaining our own awareness and
diligence. Leading human factor theorists and researchers believe that between 70% and 80% of
all aviation accidents are “attributable to human error somewhere in the chain of causation”.
(cusick et al., 2011) In this paper, I will talk about ways human error could risk safety and unsafe
habits to avoid. I will also talk about how human initiative could help safety, as well as good
habits to develop.
Human error is a huge cause for accidents. Within HFACS (Human Factors Analysis and
Classification System), the category of error includes three error types: decision errors, skill-
based errors, and perceptual errors. Decision errors can be grouped into one of three categories:
procedural errors, poor choices, and problem solving errors. Procedural errors, or rule-based
mistakes occur during highly structured tasks. Aviation is highly structured meaning there are
specific procedures to follow during each part of the flight. However, sometimes these
procedures can be misapplied or inappropriate for the circumstance, often creating an accident.
However, not all conditions have exact procedures to manage them. In these cases, the
situation will require a choice to be made among multiple response options. Sometimes poor
choices can be made, especially when the pilot has insufficient experience, time, or other outside
pressures distracting them from making better decisions. These poor choices result in choice
decision errors, or knowledge-based mistakes.
Lastly, within the decision-errors category is problem solving errors. Sometimes there are
times where a problem is not well understood or formal procedures and response options have
not been created for the particular situation. When this happens, pilots find themselves in a
situation where there are no “textbook answers” to be found. At this time, the pilot will have to
create a new solution to the problem, however reasoning processes behind this can take time. In
these situations, pilots don’t normally have a whole lot of time to reasonably process and come
up with a solution. A lot of the time, a decision needs to be made NOW. Sometimes, this can
create poor problem solving and in the end, creates more of a problem.
Finally we have skill-based errors and perceptual errors. Skill-based behavior occurs when
basic flight skills happen without much conscious thought, almost like second nature. However,
these actions are particular vulnerable to error, like failure to attention or memory. In fact,
attention failures are linked to many skill-based failures like the breakdown in visual scan
patterns, accidental activation of controls, misordering steps in the procedure, etc. Memory
failures such as skipping over things on your checklist, place losing, or forgotten intentions have
also created many errors. Perceptual errors occur, however, when sensory input is unusual, or not
what you are used to. For example, night flying or flying through weather can make your body
feel like its doing something it’s not actually doing. Pilots can run the risk of misjudging
distances, altitude, descent rates, etc. Error happens when the pilot responds incorrectly. In these
situations, it is very important to rely on your instruments, not on your visuals or how your body
is interpreting the situation. (Wiegmann, 2005)
Another way human factors could risk safety in aviation is risk stacking. Risk stacking is
the compounding of multiple risks. For example, a pilot could experience a problem with the
aircraft navigation system. On top of that stressor, maybe the pilot is also dealing with poor
visibility and an unfamiliar airport. The pilot could also be fatigued, hindering their ability to
recognize a problem and respond appropriately. This is creating a risk stacking concern. Not only
is the pilot experiencing the problem with their navigation system, but also has low visibility, is
going to an unfamiliar airport, and is fatigued. Each one of these issues alone could be a
problem, but then stacking them on top of one another creates an even bigger hazard.
One way to identify risk stacking is using the Swiss Cheese Method. This model was
developed by James Reason, a british psychologist and professor. The model metaphorically uses
slices of cheese as a barrier, each slice representing a different defense mechanism to prevent
accidents. However, like swiss cheese, these slices contain holes and weaknesses that can align
and create a pathway for accidents to happen.
For example, in April 2022, there was an accident in Idaho. The pilot was flying a cessna
caravan from Salt Lake City, Utah to Burley, Idaho. According to the NTSB preliminary report,
the weather conditions in the vicinity of Burley were poor, with visibility at one mile, light snow,
and mist. This would be hole number 1 in the pilot’s cheese. The pilot was familiar with the
airport, however, near the approach end of the runway was an active steam stack. This would be
hole number 2. The previous day, the pilot executed a missed approach in conjunction with a
diversion to an alternate airport. This likely created a decrease in the pilot’s confidence, creating
hole number 3. The more holes you seem to have, the more likely it is for an accident to happen.
(Mead, 2023)
With this being said, using the Swiss Cheese Model can help reduce risk and human error. It
can help us bolster our defenses by leading us on a hunt for holes in our cheese before we leave
for our trip. This model can help us ensure that we are properly prepared for our trip. It can help
us to remember to get plenty of sleep, properly plan for our flight by getting our weather
briefings, making ourselves familiar with the airport and any nearby obstacles, being familiar
with nearby airports just in case we get diverted to a different airport, properly preflight checking
our plane, and putting our external pressures on the back burner if we can. The swiss cheese
model also helps us recognize stressors from our external pressures and can help us decide if our
external pressures are creating too many holes in our cheese. Using this model creates healthy
habits for pilots to ensure a safe flight and minimizes possible risk and error factors.
Another way humans can help ensure minimization of possible risks and errors is by showing
an understanding of risk management and the importance of reporting risks and errors. In risk
management, there are three types of risk management strategies: reactive, proactive, and
predictive risk management. Each type of risk management strategy has particular activities and
behaviors that are useful in different situations.
Reactive risk management is meant to mitigate severity of safety events and threats. This
strategy includes actions in response to a hazard or risk occurrence. Basically, after the hazard or
risk occurrence has happened, corrective actions are taken to prevent the accident from
happening again. This strategy requires staff to report the incident so management can process
the reports and come up with a plan to help prevent the situation from happening again in the
future. Reactive risk management also requires pilots to act quickly and efficiently in response to
the hazard, as well as show high quality decision making during the situation.
The proactive risk management strategy helps identify safety concerns before the hazard
happens. It is also used to identify root causes of a hazard before they lead to the hazard
occurrence. Identifying these hazards relies heavily on reporting by staff. Reporting by staff in
this case are generally “voluntary” reports, however it is strongly encouraged to report the
situation so the hazard can be mitigated and a situation later is less likely to happen.
The predictive risk management strategy is essentially actions taken in anticipation of future
risks and hazards based on past performance data. This is done by analyzing current operations,
systems, and processes to identify areas of potential concern. If there is potential concern about a
hazard, it can be taken care of early to reduce risk in the future. This strategy relies less on staff
reporting and more on analysis of past performance issues or current operations problems to
predict possible future performance.
However, with that being said, reporting of risks and hazards by staff is incredibly important
to catch any current situations and to mitigate them as early as possible. For example, a pilot
could be doing their preflight checks and notices the power from the engines feels different than
normal. That pilot could either write it off as not a big deal because “they know the plane. It’s
fine” and therefore creates a huge risk while in the air. Or that pilot could report the issue and
have the risk taken care of before even leaving the ramp. The solution to the risk relies on the
reporting of the situation by the pilot. As you can see, staff reporting of risks/hazards is very
important to avoiding said risks/hazards and helps promote a safer environment for both staff and
passengers. (Britton, 2023)
In the end, humans have a huge impact on aviation safety. Some argue that humans have the
biggest impact on safety. They could have a negative impact if they were to make bad decisions
during an emergency, not be fully prepared for the flight, or simply by not taking care of
themselves before flying. However, at the same time, human initiative could also help aviation
safety by being prepared for flight, having the knowledge and skill to make good decisions, as
well as reporting risks and hazards to avoid dangerous situations in the future. And of course,
God is always with us holding us up and guiding us through these situations, helping us stay
safe. Isaiah 41:10 says “So do not fear, for I am with you; do not be dismayed, for I am your
God. I will strengthen you and help you; I will uphold you with my righteous right hand”. God is
always behind us, no matter what. But with that being said, it is our responsibility as pilots to
maintain our awareness and diligence by properly preparing ourselves for flight and reporting
hazards we may see along our way. We have a massive impact on everyone’s safety and it is on
us to minimize risks and promote a safe environment for all
References:
- New International Version Bible, 2011, Isaiah 41:10
- Cusick, Stephen K, Cortés, Antonio, & Rodrigues, Clarence. (2011). Commercial
Aviation Safety. McGraw-Hill Professional Publishing.
- Wiegmann, D. A. (2005). Errors. In Human error and general aviation accidents: A
comprehensive, fine-grained analysis using HFACS (pp. 1–2). essay, Federal Aviation
Administration, Office of Aerospace Medicine.
- Mead, T. (2023, May 3). SWISS CHEESE USING RISK STACKING TO MITIGATE
ACCIDENTS. AOPA. https://www.aopa.org/news-and-media/all-
news/2023/june/pilot/asi-safety-tip-swiss-cheese#:~:text=The%20Swiss%20Cheese
%20Model%20provides,for%20themselves%20and%20their%20passengers
- Britton, T. (2023, April 27). Difference between reactive, proactive and predictive risk
management in Aviation SMS. SMS Pro. https://aviationsafetyblog.asms-
