Because this has not happened before, your principle assumption remains that the procedures as specified normally work and are understood by everyone. Perhaps for this particular person the rules were not clear and well understood? Check out the substitution test! In case there is no doubt, then obviously someone knew better than the system and deliberately deviated.
What are you correcting
The person in question needs to understand how important it is that the operational practice follows the applicable rules. It is very important you do not let this opportunity slip, otherwise deviations and rule-breaking may quickly become the norm and your safety culture deteriorates. Were other workers already pointing out to their colleague he was violating the rules? You wish they had!
How are you correcting
Assuming your procedures are in order you are definitely coaching the worker back on track of nominal behaviour. You could have him train the procedure again. Check if there is an 'attitude issue' with the person involved which could make things more difficult and could necessitate the first of correctional measures like a verbal warning.
Now you are at the level of the Just Culture consequences that we are suggesting.
If you feel these consequences are not appropriate, maybe you could consider going back up the navigator and trying some other branches.
The Substitution Test helps to assess how a peer would have been likely to deal with the situation.
Johnston (1995), a human factors specialist and an Aer Lingus training captain, has proposed the substitution test. When faced with an event in which the unsafe acts of a particular individual were clearly implicated, the judges should carry out the following thought experiment. Substitute for the person concerned someone coming from the same work area and possessing comparable qualifications and experience. Then ask: 'In the light of how the events unfolded and were perceived by those involved in real time, is it likely that this new individual would have behaved any differently?' If the answer is 'probably not' then, as Johnston (1996:34) put it, 'apportioning blame has no material role to play, other than to obscure systemic deficiencies and to blame one of the victims'. A useful variant on the substitution test is to ask of the individual's peers: 'Given the circumstances that prevailed at the time, could you be sure that you would not have committed the same or a similar type of unsafe act?' If the answer again is 'probably not', then blame and punishment are inappropriate.