wwww.CulturAiles.com, a website dedicated to human factors in air safety, it presents new and innovative training suggestions about aviation safety  
Home page
Air safety
Human factors
 events (accidents and serious incidents in avoation)
what I can do...
some technical and non technical information about aviation
Inside the Boeing 737NG
About CulturAiles.com
Legal notices
Send an email to postmaster@culturailes.com

The human operator, the least reliable element of an aerodyne, but the most essential...!
Frank Caron (1991)

Last update:
26 September 2016

v2.1.0 © Copyright
All rights reserved

vocational training

A website developed by
Frank's LinkedIn page

Human Factors - No limits for the understanding of human factors

The following lines promote an understanding of Human factors (HF), through its context, its wisdom, its tools, its required experiences and its limits.

HF Context

It is fair to say that most of us in the aviation industry has a basic appreciation or a certain knowledge of the HF concept. Most people are able to talk about it in a very general way. But often it is because no other rational explanation is available as to why events happen.

HF appeared in the industry in the late 70’s. But the vocabulary then was more “CRM” (Cockpit Resources Management, a training to teach pilots how to work together) rather than Human factors. In fact, CRM is nothing more than the practical aspects of The Human Factors. In the early 90’s, there still were a number of  “strange” or unexplainable accidents which led to the extended study of HF in order to obtain a deeper and closer understanding of these events.

Can HF explain 100% of the safety issues?
Today, is there something “fashionable” about HF? First of all, many see the HF concept rather strange and subtle in approach. Secondly, most expect this field to provide all the answers for behaviors that are out of our normal understanding.

HF Wisdom

Beyond the fashion, HF is probably the most relevant approach to provide answers to safety issues. Why? According to Boeing statistics, 70% of the aviation accidents are directly related to HF.  HF means here… crew members or people operating in the front line and who else but crew members in this context. But, in fact if we look at the bigger picture and review the “system” that put crew members in the daily operating environment then we can almost say all (i.e.: 100%) incidents and accidents are HF related. Pretty hard to accept, until you ask yourself the following:

  • What/who does create new transport concepts?
  • What/who does transform these concepts in airplane?
  • What/who does design these airplanes?
  • What/who does manufacture these airplanes?
  • What/who does test these airplanes?
  • What/who does operate these airplanes?
  • What/who does maintain these airplanes?
  • What/who does provide improvement to these airplanes?
  • Etc.

For all these previous questions, the replies are the same: the human being. Humans embody the long chain from the (mental) idea to the final stage of the operation.

Thus the human being is involved at each stage of the process. However we can also process much further with new questions:

  • What manage manufactures, airlines, CAA, etc.
  • What hire the staff members?
  • What train the personnel?
  • What is in charge of their career?
  • Etc.

Again, for all these new questions, the reply is the same: the human being. It is for these reasons we arrive at the concept of systemic errors.

This means today, it is very rare for crew members (the final link of this long chain), to have alone, the full responsibility for an incident or accident.

HF is not a miracle science but a science made of different components such as knowledge, tool(s), expertise and a certain spirit not really describable.

2006: C5 Galaxy, Dover 2006: C5 Galaxy, Dover 2006: C5 Galaxy, Dover

The previous pictures show how the different sciences, fields or concepts contribute to HF. It is a multi-layered puzzle showing the numerous fields related to the HF. From left to right and from top to bottom we have the HF main puzzle layer, the live-ware layer, the social systems layer and the technical environment layer.

But every piece of each layer could be split in other numerous smaller fields. With the beside picture, it is pretty clear what psychology could bring in order to produce a single behavior.

To use a mathematical analogy, behavior is more a multiplication of different inputs from various sciences or field than a simple addition. Therefore behavior is a very strong integrated aspect of the human life.

HF is a huge, limitless concept comprising of many sciences and fields which provides us with some explanation of human behavior Even so, there are still some aspects that have yet to be discovered in order to bring a clearer view of behavior science.

HF Tools

HF is often criticized for its… lack of tools. Every airline wants a way to assess its crew performance, estimate future staff member’s abilities or intelligence and how they can cope with stressful situations. Let's take a simple example: intelligence.

The usual answers to this question use to be: the way we adapt to situations, the way we learn, the way we memorize, the way we talk and the way we pilot aircraft (the skills), etc. This leads us to ask further questions, as: What is a good way to memorize? What is a good way to learn? What is a good way to adapt? How smart must be a pilot? The airline industry deals daily with such questions. What is a good pilot? What is a good Captain? What is good CRM?

CRM, the way we should behave in a cockpit… Everybody agrees that CRM concepts are great. They are so useful… but when you want to measure its effects, or when you want to assess the result of every training session it becomes a headache. Some countries have started programs in order to define a CRM evaluation tool, however the results are not really convincing.

One of the real problems with HF is its lack of references.
If someone wants a precise idea about his weight, he can use a weighing scale. This balance of this scale has been calibrated with a standard weight. When someone wants to measure the intelligence, or a pilot behavior, or the level of stress in certain situation however, this won't be easy. Because we do not have any reference or measuring tools with a (clear) standard to assess such criterion.

Based on that, how is it possible to hire the right people for the right position? Just as an example: when the French Air Force wants to recruit 30 pilots, they receive more than 3000 applications. 2500 applicants will be rejected on the basis of the psychometric tests, leaving 500. 400 will be rejected because of the medical examination, leaving 100. In the psychological interviews, 70 will be rejected, leaving 30. The hiring process is over. Thus, the selection process kept only 1% of the applicants. Then these 30 people are now going to start very demanding flight training. The training may take the form, one day, one flying task. If you do not succeed, you are either relieved or sent to another less demanding unit and most of the time not as a pilot. During this training process, 20 are rejected. At the end, out of more than 3000 applicants, 10 will reach a unit as a fighter pilot (only 0.3%).

Here is another point. There is always at least one pilot in every fighter pilot group, who has great difficulty flying military operations. He succeeds the hiring processes phases. He succeeds the training phases, where he behaved as expected. Thus, he got his fighter pilot wings. But for reason(s) nobody can explain, he cannot reach the military operations standard. Why couldn't this type of candidate be detected before reaching his squadron? This example shows how the ideal hiring tool may not exist.

HF and Expertise
The HF wisdom is not sufficient. Experience is more than relevant to supplement the knowledge acquired.

The goal is to provide a strong framework in the comprehension of the daily aspects of HF. Daily operations also means dealing with every personality, every type of person we can imagine and every way of behaving that is possible. That is probably the most difficult part because the more experiences you gather, the more powerful your understanding of HF.

Today, for the industry a good operator is mainly an experienced one…

Expertise, as the result of experience, is a great and wonderful concept. But if you pay attention to every aviation accident, it is experts who make them. It may be cockpit crews with at least 6000 hours total time and more than 1000 hours on type, mechanics with years of practice, senior managers or senior Air Traffic Controllers with years of experience!!! These people are not beginners in the industry. Regarding accidents, the investigations show they were judged very good professionals by their colleagues.

All were well trained and experienced with regard to the aircraft they flew and company/organization procedures. All were very motivated staff members. So, why despite their numerous professional qualities is it that these people could not prevent an accident?

The answer seems obvious but at the same time, questionable. Experience is not sufficient to guarantee a safe operation, although today most of the industry relies mostly on experience for its personnel selection.

HF Limits
The way knowledge, tools and expertise is used is one point. The other point concerning the limits of HF remains. One of the greatest abilities of the brain is to create what does not exist.

The unimaginable may happened from HF point of view!

Sometimes, we don’t really want to think about the unimaginable because we do not want it to happen. Very often, this is not rational at all. To make it simple: accept the impossible as possible in the HF context, and bear in mind it is not only a matter of aviation…

The best example comes from WWII. When the British intelligence reported the concentration camp horror, NOBODY could believe such atrocities on such scale.

Just because no one could accept there were human capable of such behavior. Therefore, the first reports were totally ignored. "For the common people of Britain, Gestapo and concentration camps have approximately the same degree of reality as the monster of Loch Ness" wrote Arthur Koestler, in his 1943 wartime essay: "A Challenge to 'Knights in Rusty Armor'".

Some would wonder what is the relationship with commercial aviation...

In 1998, an A320 landed in Charles-de-Gaulle (Paris) airport. The aircraft was 35 minutes behind schedule. He had just a 25 minutes turnaround, with a departure time within 30 minutes. Everyone was in a rush, trying to make the turnaround as short as possible in order to maintain the slot time. The aircraft taxied out and was cleared for takeoff. When takeoff power was set and the aircraft started rolling, the captain didn't feel right, thinking he had forgotten something. He immediately questioned his FO while he retarded the throttles: Did we refuel? Take off was halted and the runway cleared, because the answer was… NO.

HF does not have limits!

Some “things” could not be possible. Nobody in the aviation industry could imagine a crew forgetting the fuel. There are SOPs, checklists, (pilot with) hours of experience, all should compensating for such error(s). However, in certain circumstances, the crew is going to behave totally unexpected. Simply, HF breaks the limit of what we perceive as our understanding of human behavior.

In conclusion

  • If you really want to deal with HF, keep your mind fully open. Peculiar contexts require some acceptance beyond what we assume is how the real world works.
  • We need to accept and integrate every tiny piece of information from every field of knowledge, since most of our behavior relies on a multiple of components (combinations).
  • Do not expect to use strong and advanced tools. In fact, our own inquisitive mind is the right tool when dealing the workings of other minds.
  • Be ready to deal with every possible circumstance. Not because people are difficult to deal with but because everyone tries to build the best situation from his or her own point of view in order to get the most suitable solution.


Frank Caron, May 2006.

quick links

5 steps to convince about safety

Why air safety improvement is too slow (organisation)?

Why air safety improvement is too slow (culture)?

Why training is the main solution to human factors issues

Human factors still the current challenge of the industry

No limits for the understanding of human factors

Suggestions for a discipline committee

Too long briefings

Current CRM have reach its limits

Aviation safety international legal definitions

Two statements about fatigue every manager must know