Human factor investigations

Presentation by John Chappelow from his website

John describes a taxonomy that he uses in training non-human factors specialists on accident investigation courses. Once a narrative description of an incident has been
broken down into discrete events, each event is examined to determine the type of error involved according to a simple classification based on the cognitive elements of any task cycle. They are:

1. Perception,
2. Intention,
3. Action.

This is achieved by asking questions as follows.

1. Did you perceive the situation correctly? If no, was it
a. Detection failure
I didn’t see it
I didn’t hear it
I’m sure it was green when I looked
It appeared to be locked when I checked
b. Misjudgement
The gap looked big enough
It didn’t seem to be going that fast
c. Communication failure
I thought he said…

2. Were your intentions appropriate?
a. Inappropriate model
I hadn’t appreciated that…
I obviously misunderstood what was required
In retrospect, the briefing could have been clearer
Suddenly, the plan went pear-shaped
b. Inappropriate evaluation of risk
I saw a simple way to solve the problem
We thought it would work
To save time, I used a different tool/method
We always do it this way on this unit
The laid down procedure takes too long
c. Responsibility management
I thought someone else would…
d. Malicious intent

3. Did you do what you intended to do?
a. Lapse
I forgot to…
b. Slip
I intended to do A but did B instead
c. Skill
I applied too much force
d. Response time
I was too slow/too quick


According to John "this approach has proved robust and easy to use, and, importantly, it can facilitate investigation of possible causal factors by identifying the more likely candidates."

Andy Brazier