If you’re a pilot, you have probably been bombarded with the rule of thumb that roughly 70% of aviation accidents are caused by Human Factors, not technical malfunctions. We constantly get reminded of this, whether in the classroom, during safety meetings, or in accident reports. The Dirty Dozen of Human Factors can influence our performance, and are often caused by a various amount of (external and internal) variables. So what are they?

Keep in mind that this is simply a framework to make us think about our actions a little bit more, not a complete representation of reality. To get a more accurate picture, the entire system will need to be considered (environments, companies, regulators, etc).

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Lack of Knowledge

This one is close to our hearts here at Pilots Who Ask Why. It’s the essence of what we do here! Knowing your aircraft, the rules, meteorology, understanding procedures and why we do them, it all feeds into a complete and accurate mental model that we use every day to make the right decisions!

How can you possibly expect yourself to make effective, safe, and efficient decisions if you do not have the knowledge to come up with them and back them up?

The hardest thing for a lot of people is to stay motivated to keep learning. To see every day as a learning day, to REALLY understand what and why you’re doing something. This understanding, compared to the ‘oh because James told me to’ mentality, is often what separates the safe aviators from the ones featured in accident reports.

Ask, enquire, challenge, and grow. That’s why we’re all here! To make sense of the world and industry we’re in, and to guard ourselves from making non-sensical decisions because we didn’t really understand what we were doing. (If you’re new here, welcome! There’s a lot more to come!)


This is basically the general ‘accepted’ practice within an industry or industry branch. In this context, it refers to deviations from SOP with the reason of “I like it better this way”.

You might have noticed cultural difference if you’re swapping from the airlines to a private charter business, from the HEMS industry to the offshore industry, or any other career change with a vastly different mission including changing from rotary wing to fixed wing or vice versa.

Norms are the result of cultures. Cultures are the result of people. And people are usually the result of different demographs that certain industries or operation tend to attract, their history, experience, and different lessons learnt along the way.

If you think your workplace doesn’t have a ‘culture’, think again. If it’s hard to quantify what culture is, just think of this: Ever heard or thought ‘this is just how we do things around here’? That is culture. It’s a combination of the training, people, and general practices that come with your type of operation or company.

Don’t take this for granted! It can be both good and bad practices, but awareness of things you do on a day to day basis, and WHY you’re doing them that way, can help with creating a safe workplace culture.

This, together with unambiguous SOP’s, a just culture, and proper training, will all help combat norms that don’t benefit safety.


We’ve covered this one extensively in our previous article about fatigue management. Fatigue has a massive impact on any safety critical process.

We’re all humans, and humans have basic requirement that need to be met in order to function properly. The Sleep – Nutrition – Exercise triangle turns out to revolve more around sleep than the other 2.

Fatigue is a very normal human reaction to prolonged levels of stress. Stress in the conventional sense, but also the ‘stress’ on the brain and body that anyone experiences during a normal day while awake.

A common misunderstanding is ‘well I’m not stressed so I’m all good right?’. Not really. Even with a perfectly adequate amount of sleep, having a hectic day with lots of decision making and hurdles to overcome, you could be mentally depleted by the end of the day. Having to stretch this out a few hours to complete a mission or delayed flight carries its own risk.

Fatigue influences decision making, alertness, mood, and situational awareness amongst others. All things that are super important to safely carry out your duties as a pilot, engineer, air traffic controller, or anyone else contributing to safety.

If you’re feeling fatigued, make sure you make yourself and colleagues aware, and have someone doublecheck your actions.

Lack of Awareness

Situational Awareness (SA) is another term thrown around everywhere, and for good reason. Lack of SA can have so many different negative effects on flight safety. It is a broad term that basically includes your entire environment. The aircraft, airspace, avionics, your other crew member and what he or she is thinking, ATC, etc.

If you’re feeling behind the aircraft, it is very difficult to pick up on cues that are not very obvious. It can lead to tunnel vision where you are ignoring lots of available resources.

Thinking ahead and expecting certain negative outcomes so you can prepare for them is a crucial trait for any aviator.


Stress.. None of us are fans of it, but it’s a part of life. There are 2 main types: chronic stress and acute stress.

Acute stress can come and go based on your environment and what you’re having to deal with.

Part of the problem is the difference between your ideal reality, and actual reality. The bigger the difference, the more potential there is to experience acute stress.

Of course some people handle this difference a lot better than others. It depends on your mood, experience, personality type and other variables.

Stress increases adrenaline in our brains, which is supposed to help with alertness. It can however, influence our decision making in bith good and bad ways. The arousal curve shows this perfect level of stress:

This means that a complete lack of arousal (i.e boredom) can have negative consequences on your decision making, just like high levels of stress can.

Recognising where you are on this curve can help you realise you might need to take a few deep breaths to calm yourself down if you’re on the right side of the curve. If your brain is not getting enough stimulation, you might need to up your workload to get to the optimum level.

Chronic stress on the other hand is a long term buildup of factors that need addressing or might be hard to deal with. Home situations, divorce, problems with the kids, or other things that keep you busy.

This can be made worse if it’s combined with a lack of sleep, proper nutrition, or exercise. Try to take as much care of your brain and body as you possibly can.


How often have you experienced the following:

You’re in the zone, completing your tasks while in a normal workflow. Everything is going great and you’re working together as a team. But then, something comes up that’s out of the ordinary. You stop what you’re doing, to focus on whatever just came up.

After dealing with the ‘distraction’ you go back to what you were doing. And after a while, it turns out you forgot something very simple. A step on the checklist, a landing light, chocking the aircraft, putting the fuel cap on, noting the fuel over a waypoint, etc.

Why do we make these silly errors? Often it’s simply caused by an interrupted workflow. After a distraction it can be hard to resume processes EXACTLY where you left off.

You might even have double-checked you were still doing the right thing when you came back to your workflow and still forget something. If this happens, it can also cause issues later on.

A good practice is to repeat the last task on the checklist after an interruption just to make sure you haven’t missed anything.

Distractions are also the main contributor to forgetting things you previously encountered. If you’re getting interrupted, it helps to be aware that your normal workflow got interrupted and to doublecheck yourself.

The other counter measure is to have ‘safezones’ where during certain workflows you do not allow yourself to get interrupted. This could mean completing a normal checklist before interacting with something out of the ordinary.

Lack of Communication

Communication is a key contributor to safety. There are so many channels we interact with on a day to day basis. Ground crew, flight crew, cabin crew, air traffic controllers, dispatchers, HQ, the clients, passengers, police, medical crew, etc.

Efficient communication is partly a technical skill, but it’s also very much an emotional skill. Unfortunately, we as pilots tend to score extremely low on Emotional Intelligence (EI). EI is defined as:

“The capacity to be aware of, control and express one’s emotions, and to handle interpersonal relationships judiciously and empathetically.”

Understanding your crew’s mental state, reading body language and vocal expressions are all cues that could be completely missed if we ignore this part of the equation.

Lots aviation material goes into in-depth explanations of how to communicate effectively, but rarely go into the human emotion side of things.

We aren’t robots. Some of us might like to be one, but we’re not.


It’s possible to become complacent after a few hours of flying, months of flying, or years of flying the same type of operation.

There are quite a few operations where you might think ‘well we’ve done this route 2345987 times, or “this is the 3rd time today we’re flying this approach into Heathrow, so what could go wrong?”

A false sense of security can come with repetition. It’s tricky to deal with, as we’ll all eventually do the same approach back into base. How do we stay fresh and focussed during these moments? Vigilance!

Vigilance is the antidote to complacency. It is our ability to continue to monitor ourselves effectively for a period of time and think ahead about potential what if’s.

Anticipating things going in ways we do not want them to go, and coming up with a plan B and C, is crucial if we want to deal with emergencies efficiently.

It’s up to us to make sure we stay vigilant and still anticipate for things not going to plan, even while flying the same approach for the 5th time that day.

Lack of Teamwork

There are people within certain operations with more responsibility than others, but we all contribute to safety the moment we enter the hangar (and even before that).

Teamwork and leadership are very relevant for lots of operations within aviation. We need clear direction, and a shared view of what we’re trying to accomplish to get what we want: an efficient and safe flight.

In order to have a good team, you need members with a shared mental model of what is and isn’t acceptable. What does that mean in aviation? Well we need to have a shared understanding of:

  • Operational Limitations
  • General Emergencies
  • Debriefing opportunities
  • Roles and responsibilities
  • A clear goal and aim
  • Effective communication

This list is not exhaustive ofcourse, but these are the bare minimum aspects that will need to be covered if you want to have an effective team as a crew.

Lack of Assertiveness

In essence, assertiveness gives us the power to say “No this isn’t right, we need to stop and think’.

This is a really important element in aviation. If you’re surrounded by people who will always just say yes and enable you in what you come up with, at some point things will go wrong.

We’re all flawed, no one is perfect. Unfortunately though, there are still many aviation cultures where speaking up and saying ‘I don’t think this is correct’ can result in you losing your job or being shouted at. Cockpit gradient is still a massive issue (and we’ll cover this in the future).

It’s this type of thinking we need to completely purge as an industry. Whether you have 15000 flight hours, or 150, if something doesn’t look right, it needs to be pointed out and taken seriously.

Assertiveness does not mean aggression. There is a professional way in which we can calmly explain we do not agree with the current events, without creating hostility. Finding the right balance is crucial for having a safe cockpit.

Have you noticed instances where you couldn’t speak up?


Pressure is another topic we’ve covered before at Pilots Who Ask Why. There are a lot of different types of pressure.

Commercial pressure is by far the biggest one. It’s the conflict of interest of companies or task oriented people and flight safety.

Often, saying no will result in financial downsides for the company.

Realising that flight safety is paramount and trumps the amount of profit that day is step one, and a step still not understood by many companies across the world.

It’s not just commercial pressure caused by companies though. Get home-itus (wanting to get back home), pressing on, peer pressure, client pressure, ego, and macho mindsets are all creating an environment where flight safety is at odds with other goals.

While this doesn’t necessarily have to cause accidents, it will increase the risk of something unsafe happening.

Assertiveness helps with counteracting pressure.

Lack of Resources

If the members of any operation are not equipped with appropriate tools, equipment and training, how can you expect safety levels not to be impacted?

If an engineering who is trying to do his job does not have replacement parts readily available, and combine it with commercial pressure, you get situations where people are incentivised to cut corners.

Resources aren’t just equipment though, it’s access to SOP’s, uniforms, training, and overall wellbeing at work.


These are the dirty dozen! All of these have significantly influenced aviation accidents at some point in time.

Because they’re defined and thoroughly researched every year, we as an industry can learn from mistakes and improve flight safety as time goes on.

Most accidents are still caused by Human Factors. Let’s see how this changes in the years to come!

Categories: Safety

Jop Dingemans

AW169 HEMS Commander | Founder of Pilots Who Ask Why | Aerospace Engineer | Former Flight Instructor


Paul · December 17, 2022 at 11:13 AM

Excellent article, comprehensive and thorough! Thank you!

David D Wallace · December 14, 2022 at 8:47 PM

Thank you sir for all of the information.

    Jop Dingemans · December 14, 2022 at 8:58 PM

    My pleasure David, please keep your valuable feedback coming – it’s really appreciated!

Michel · December 13, 2022 at 12:13 PM

Perfect and valid indications!

Vidal Yaguarin · December 12, 2022 at 9:52 AM

Excellent article buddy, it’s so useful for everyone!!! On MRM asa well as CRM.. congrats

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