MENASASI Middle East and North Africa Society of Air Safety Investigators

An Experienced Error


Whenever discussing the relation between experience/training and human error in class the answer usually given is the more experience we have and the more training we receive at any operation, the less likely it is for us to commit errors but the answer that really matters is not about the difference in the number of errors but in the types or errors committed by experts. 

The Danish safety engineer Jens Rasmussen divided human error into three sub-groups: knowledge based, rule based, and skill based. It makes complete sense that a well-trained/experienced individual is less likely to commit errors due to a lack of knowledge or the misapplication of a rule. On the other hand, a skill error is a problem for the expert not the novice where one’s proficiency and experience may actually be there downfall as bizarre as it may sound.

Whenever I bring up this point in class the usual answer I get from crew members is “Are you saying that experienced personnel have fewer skills....”

Skill based errors can be defined as failures that occur at the execution phase of an intended action and usually occur on routine activities, tasks which are familiar and have been completed many times before successfully, it can be as simple as pouring coffee, operating an Airbus 320 door, or using stitches to close a medical incision. As a result, of the hundreds or thousands of hours of experience on a certain task, the task itself becomes more routine and less complex. I always tell my trainees to go back to their first commercial flight and how the tasks felt more complex but as the individual’s experience increases so does their familiarization with the operation (which in itself isn’t a bad thing). 

The more familiar a task is, the easier is becomes, and the more room there is for the mind to get distracted. Every responsible individual comes with the notion of wanting to perform at a high standard but working environments are full of distractions and interruptions, when these interruptions align with familiarized tasks we suffer failure.

I remember one class we were discussing cabin crew error and in-advert slide deployments and one of the more experienced crew members said “I’ve been flying for over 20 years and I’ve never had a slide deployment want to know the secret” wanting to know the answer I asked how to which she replied “I talk to my door, I ask it questions, I even have conversations” to which I jokingly replied “You can talk to the door all you want but the moment you think the door is talking back please go to medical and get checked” which the whole class took in a humorous manner.

The term she was looking for is called a “chronic unease” which is the effective questioning of our environment and the actions we take throughout an operation, trying not to assume and thoroughly looking for possible short comings. With that being said errors are going to happen, in all respect to experience, training, and a chronic unease there will always be a variability in human performance, but the question that should be asked isn’t how do we beat the error out of the human but how do we implement a system that allows people to fail safely, which is a different topic for a different day. 


Abdulaziz Shabra

Abdulaziz Shabra

Safety and Human Factors Instructor at PRINCE SULTAN AVIATION ACADEMY