What the rules ask for
- Findings. After a finding, the operator shall "identify the root cause of the non-compliance", define a corrective action plan and demonstrate it to the authority ORO.GEN.150. ATOs have the same duty in ORA.GEN.150, DTOs in DTO.GEN.150. The guidance adds: "Proper determination of the root cause is crucial for defining effective corrective actions to prevent reoccurrence" GM1 ORO.GEN.150, and the plan "should address the effects of the non-compliance, as well as its root cause" AMC1 ORO.GEN.150(b).
- Occurrences. Each organisation analyses occurrences "in order to identify the safety hazards associated with identified occurrences or groups of occurrences", and determines "any appropriate corrective or preventive action" Reg 376/2014 Art 13(1). It implements that action "in a timely manner" and monitors "the implementation and effectiveness of the action" Art 13(2).
- Your own audits. The GM3 non-compliance report for non-complex operators has a "root cause" field next to the correction and corrective action GM3 ORO.GEN.200(a)(6).
No rule prescribes a method. What the authority judges is whether your corrective action aims at a cause that, once removed, stops the problem coming back.
Symptom, cause, root cause
| Level | Question it answers | Example |
|---|---|---|
| Symptom | What was found? | A student flew a solo flight with an expired medical certificate. |
| Direct cause | What made it happen this time? | Nobody checked the medical before authorising the solo. |
| Root cause | Why did the system allow it, and would it happen again with other people? | The solo authorisation step has no document check and nothing tracks expiry dates. |
A useful stop rule: keep asking why until you reach something your organisation controls and can change, a procedure, a form, a resource, a training gap or an oversight step. "The instructor forgot" is where the analysis starts, not where it ends. That is also what a just culture asks: look at the system first, and keep blame for the rare cases the rules set out.
Three methods for a small team
| Method | How it works | Use it for |
|---|---|---|
| 5 whys | Write the problem, ask why it happened, then ask why again of each answer, usually three to five times, until you reach a cause you control. Check each step with a record or a conversation, not a guess. | Most findings and simple occurrences. Ten to thirty minutes. |
| Fishbone | Put the problem at the head and check six bones for contributing causes: people, procedures, training, equipment and aircraft, environment, and organisation and oversight. Then pick the causes that matter. | Problems with several causes, or when 5 whys keeps landing on one person. |
| Timeline | Put what happened in order, with times, from the records and the people involved. Mark where something differed from the procedure or from what was planned, and ask why at each of those points. | Occurrences, where the sequence matters more than one cause. |
Whichever you use, look at your findings register first. If the same requirement was found before, the earlier corrective action did not work, and the root cause is probably somewhere else.
A worked example: 5 whys
Illustrative only: a small ATO, an internal audit finding.
- Why did the student fly solo with an expired medical? The instructor did not check the medical before signing the solo authorisation.
- Why not? The instructor looked at the student's page in the booking system, which shows the training progress but not the medical.
- Why does the check rely on that page? The procedure says "the instructor ensures the student holds valid documents" without saying which, when or how it is recorded.
- Why is it written that way? It dates from when the school had a handful of students and the head of training knew every expiry date. Nobody tracks medical expiry dates for students.
- Root cause: the solo authorisation step has no recorded document check, and student medical expiry is not tracked.
| Part of the answer | Example |
|---|---|
| Correction | The student stopped flying solo until the medical was renewed; every current student's medical checked the same day, none other expired. |
| Corrective action | Medical expiry date added to the student list, with a warning 30 days ahead; a "medical valid until" line added to the solo authorisation form; instructors briefed. Owner: head of training, 30 days. |
| Evidence | The revised form with its revision and date, the student list with the new column, the briefing record. |
| Effectiveness check | In three months, sample ten solo authorisations: all show the medical date. |
Writing it down
| Weak root cause | Stronger root cause |
|---|---|
| Human error. | The checklist has no step for X, so the check depends on memory. |
| The pilot was not aware of the procedure. | The revision was sent by e-mail with no confirmation that it was read, so two pilots used the old procedure. |
| Lack of training. | The recurrent training syllabus does not cover the 2026 change to Y, so nobody trained after March knows it. |
| Oversight. | The audit programme has not covered area Z since 2024, so the drift went unnoticed. |
A good root cause statement is one sentence, names a part of your system, and is something you could check has changed. If it reads like a person's name, go one why further.
Isolated or systemic
Before you close the analysis, check the extent: is this one case, or would a sample of similar records show the same? Some authorities ask you to state it. Sampling also protects you: a correction that fixed one record while ten others have the same gap is the kind of thing the next audit finds. Then plan the effectiveness check. The management system asks you to "verify their effectiveness" for risk mitigation ORO.GEN.200(a)(3), and Art 13(2) asks you to monitor the effectiveness of actions taken after occurrences. For deadlines and levels, see how to close a finding.
Sources: EASA Easy Access Rules for Air Operations (March 2026: ORO.GEN.150, AMC1 and GM1 ORO.GEN.150, ORO.GEN.200, GM3 ORO.GEN.200(a)(6)), Easy Access Rules for Aircrew (October 2026: ORA.GEN.150, DTO.GEN.150), Regulation (EU) 376/2014 (Art 13). The methods and examples are common practice, written up by us. Rule text checked 31 October 2026; where this guide and the Official Journal differ, the Official Journal text prevails.
Questions we hear
Is "human error" a root cause?
Rarely on its own. Corrective action is meant to "eliminate or mitigate the root cause(s) and prevent recurrence" GM1 ORO.GEN.150. Ask why the procedure, training, workload or oversight let the error through. That is usually where an action can work.
Does EASA require 5 whys or a fishbone?
No method is prescribed. The rule asks you to identify the root cause ORO.GEN.150(a); how is up to you. Note the method on the finding, so the next person can follow your reasoning.
How long should a root cause analysis take?
For most findings at a small organisation, under an hour. Spend longer when the finding is a repeat, when it is a level 1, or when an occurrence had a serious outcome.
Who should do it?
Someone who knows the work, with the people involved, not only the manager of the area. A second person who was not involved is a good check that the reasoning holds.