ACR Pro: root cause analysis with 5 Whys, Ishikawa and Cause Tree

ACR Pro is a root cause analysis and investigation tool that runs in the browser. It brings together three methods — 5 Whys, Ishikawa (6M) and Cause Tree — in a single HTML file, with no installation, no account and no server.

With it you record the event, organize evidence, team and problem statement, build the analysis in the chosen method, mark the root causes, record the actions and generate the report and diagram as PDF. ACR Pro was developed by Segurize360.

ACR Pro was developed mainly for professionals who carry out investigations and root cause analyses, especially in Occupational Health and Safety. The training examples also cover process quality, so the tool can serve other professionals who need to structure a root cause analysis.

It supports the investigator's work: it does not replace technical knowledge, the analysis of evidence or the professional's responsibility.

Root cause analysis is the set of methods used to understand why an unwanted event occurred — an accident, a near miss, a deviation or a nonconformity — going beyond the first obvious explanation. The goal is to reach the system, management or design failures that, once corrected, keep the problem from happening again, rather than just pointing at who made a mistake.

An analysis usually involves preserving the scene and gathering evidence (people, documents, physical conditions and environment), describing the event clearly, listing the causes, verifying each one with evidence and defining corrective actions for the root causes.

The 5 Whys are a linear chain of “why?” questions. You start from the problem and ask why it happened; the answer becomes the next question, and so on until you reach a cause that, if fixed, prevents recurrence. The number five is a reference, not a rule: it can be fewer or more questions. The method was popularized by the Toyota production system.

It tends to work well when causes are more direct and linear. Illustrative example: the equipment stopped (why?) → the fuse blew (why?) → there was an overload (why?) → preventive maintenance was not done (why?) → the maintenance plan did not cover that item.

The Ishikawa diagram, also called the fishbone or cause-and-effect diagram, was proposed by Kaoru Ishikawa. The problem sits at the fish's “head” and the possible causes are organized into categories along the bones.

In the 6M version, the categories are Method, Machine, Material, Manpower, Measurement and Environment. It is useful for broadly mapping possible causes before going deeper — many teams combine Ishikawa with the 5 Whys to dig into only the causes that really matter.

The Cause Tree is a method of French origin widely used in accident investigation. It starts from the event and branches into ever deeper causes, showing how one fact leads to another. Relationships between causes can be AND (all must occur together) or OR (any one is enough). It suits events with several intertwined lines of cause.

In ACR Pro, each box in the tree can be marked as Confirmed, Hypothesis or Discarded, and root causes are highlighted, which helps separate what already has evidence from what still needs to be verified.

There is no single script, but a sequence like this usually works well:

1. Secure the site and preserve the scene before anything is moved.
2. Record the event: what happened, when, where, the actual impact and the potential impact.
3. Gather the evidence (people, documents, physical conditions and environment) before it is lost.
4. Define the team that takes part in the investigation.
5. Choose the method: Cause Tree for events with several lines of cause, 5 Whys for more linear causes, Ishikawa to map broadly before going deeper.
6. List the causes and write each one as a verifiable statement, not as an opinion.
7. Verify the causes with evidence, mark the root causes and define corrective actions.
8. Document the analysis in a report.

ACR Pro organizes these steps in a single tool:

• Investigation assistant with a guided script: evidence, problem statement, team and tree.
• Three methods in one place, switching methods without erasing the work done in another.
• Cause Tree with AND/OR relationships, statuses (Confirmed, Hypothesis, Discarded) and root cause marking.
• Action panel to record the actions that eliminate the root causes.
• Report and diagram as PDF.
• Export and import analyses as .json, for backup and to take the analysis to another computer.
• Training with 14 ready-made examples inside the tool.
• Interface in English, Portuguese and Spanish.

ACR Pro runs entirely in the browser, from an HTML file, and does not depend on a server: the analysis works without internet. The exception is the first PDF generation, which downloads a library once; the browser keeps it and, from then on, everything works offline. Without the library, ACR Pro opens the browser's print dialog so you can save the PDF from there.

Data is saved only in the local storage (localStorage) of the browser you work in. There is no cloud or server. Clearing the cache, switching computers or using an incognito window makes the analysis stop appearing, so export a .json backup every time you finish an important session.

ACR Pro generates two PDFs: the investigation report, with event data, team, problem statement and collected evidence, and the analysis diagram, according to the method used. The files contain real (selectable) text, not images, and are downloaded to the browser's Downloads folder.