MEDA — Maintenance Event Decision Aid

MEDA is a structured interview-based process for investigating events caused by maintenance technician or inspector error. Developed by Boeing in the early 1990s in collaboration with major airlines, a maintenance trade union, and the FAA, it was the first systematic method to examine undesirable maintenance behaviour in its full procedural and organisational context.

The method treats the maintenance technician not as the sole cause of an event, but as one component within a broader socio-technical system — where both technical factors (tooling, documentation, aircraft systems) and social factors (teamwork, communication, supervision) influence performance. Identifying and addressing the contributing factors within that system is far more effective than retraining or punishing the individual involved.

CORE PHILOSOPHY

• Errors are not intentional. Even violations typically occur because a person is trying to do the right thing under difficult conditions, or because non-compliance has become a work group norm. Punishing an individual does not reduce the probability that others will make the same error.
• A series of factors typically combines to produce an error — field testing found an average of four contributing factors per event. Fixing even a subset of them significantly reduces the likelihood of recurrence.
• Most contributing factors are under management control. Addressing contributing factors to low-level events also helps prevent more serious ones — the same factors that cause minor incidents cause major ones.

HOW THE MEDA PROCESS WORKS — AND WHAT IT MEANS FOR YOU

1. An event occurs — a delay, a finding, a near miss. We will receive a report. That is the starting point for a MEDA investigation.
2. Before anyone contacts you, we first confirm that the event was related to maintenance technician or inspector performance. If it was a purely technical failure MEDA does not apply and an engineering investigation takes over instead.
3. We identify who performed the work. This is not about finding someone to blame — it is about finding the right person to talk to.
4. We will organize a meeting (in person, online). Using the MEDA Results Form, we go through what happened — what the error or violation was, what conditions made it more likely, and what you think should change. You are the person closest to what happened. You know better than anyone what made that task difficult, what was unclear, what was missing. We need that knowledge.
5. If needed, we follow up — with colleagues from the same work group, with planners, with stores. We may also look at the tools you mentioned, check the lighting, or verify whether something you described as common practice is indeed how the job is normally done.
6. Everything we find goes into a database. Over time — typically after 20 or more investigations — patterns start to emerge. The same contributing factors tend to appear again and again across different events, different people, different shifts. That is where the real value of the process lies.
7. Management reviews the findings and decides what to change — a procedure, a label, the lighting in a bay, the shift handover process. Some changes happen quickly after a single investigation. Others require data from multiple events before the case is strong enough to act on.
8. Feedback. We tell you what changed and why. If you took part in an investigation, you see the result of that conversation. That is the point — the process only works if it is a two-way exchange.

When we interview you after an event, you are not a suspect. You are the most important source of information we have. You were there. You know what the procedure looked like in practice, not just on paper. You know what the workspace was like, what the time pressure felt like, what everyone else around you was doing. Your input does not just explain one event — it helps prevent the next one. That is why we ask, and that is why it matters that you answer honestly.