ROV Incident Investigation: Root Cause Analysis for Experienced Operators

Incident investigation is one of the most important and least well-practiced skills in the ROV industry. Most experienced pilots have been involved in at least one significant incident — a lost vehicle, a tether damage event, a flooding event during intervention. Fewer have been part of a rigorous investigation that identified the root cause rather than stopping at the obvious proximate cause. This guide is written for experienced operators and supervisors who want to conduct investigations that produce real learning, not just reports that satisfy regulatory requirements.

Near-Miss vs Incident: Getting the Classification Right

The ROV industry frequently under-classifies events — near-misses are treated as non-events and incidents are reported as near-misses to avoid regulatory obligations. This is both ethically problematic and operationally counterproductive. A near-miss where an ROV tether was close to wrapping a mooring chain but was recovered in time contains exactly the same causal information as a tether loss event — except that it costs nothing to investigate and carries no regulatory consequence. Treat near-misses with the same investigation rigor as incidents. The only difference is the outcome; the causal chain is identical.

Event Classification Framework

• Near-miss: An unplanned event that did not result in damage, injury, or production loss but had the potential to — mandatory to report and investigate internally
• First aid incident: Minor injury or equipment damage requiring simple remediation — internal investigation required
• Recordable incident: Injury requiring medical treatment beyond first aid, or equipment damage exceeding a defined threshold — formal investigation and client notification typically required
• Lost time incident (LTI): Injury resulting in lost work time — regulatory reporting required in most jurisdictions, formal investigation mandatory
• Major incident: Significant equipment loss, structural damage, or serious injury — full regulatory reporting, possible third-party investigation, and potential suspension of operations
• High potential near-miss (HiPo): A near-miss assessed as having potential to cause a major incident — investigate at the same level as a major incident regardless of actual outcome

The 5-Why Method: Practical Application

The 5-Why technique is widely taught but frequently misapplied. The method asks 'why' repeatedly until the root cause — typically a systemic or organizational failure — is reached, rather than stopping at human error or equipment failure. A tether damage event investigated properly might proceed: Why was the tether damaged? — It contacted the jacket structure. Why? — The pilot did not maintain sufficient standoff. Why? — The USBL position was incorrect and the structure was not where the pilot expected. Why? — The system had not been recalibrated after the vessel repositioned. Why? — The recalibration procedure was not included in the dive planning checklist for repositioning operations. This root cause — a gap in the checklist — is actionable and systemic. 'Pilot error' is not.

Fishbone Diagram Analysis for Complex Events

For incidents where multiple causal streams converge, the Ishikawa fishbone diagram provides a more structured framework than the linear 5-Why approach. The diagram organizes potential causes into categories — in an ROV context these are typically Equipment, Procedures, People, Environment, Management System, and Communication. Each category is explored independently, then connections between causes across categories are identified. A flooded electronics canister might have causes in Equipment (O-ring beyond service life), Procedures (no torque specification for canister closure), Management System (no competency check for technicians assembling housings), and Environment (cold water reducing O-ring elasticity). The fishbone forces the team to consider categories they might otherwise overlook.

Regulatory Reporting Requirements by Jurisdiction

Reporting obligations vary significantly by jurisdiction. In UK waters, RIDDOR applies to workplace injuries while the HSE has additional requirements for offshore operations. In Norwegian waters, the Petroleum Safety Authority Norway (Ptil) requires reporting of major incidents and serious personal injuries under the Activities Regulations. In US Gulf of Mexico operations, Bureau of Safety and Environmental Enforcement (BSEE) reporting requirements apply. Supervisors and vessel superintendents must be conversant with the requirements of every jurisdiction they operate in — thresholds, timeframes, and formats all differ. When in doubt, report early. Regulatory bodies consistently treat timely voluntary reporting more favorably than delayed or prompted reporting.

Building a Just Culture on Your Team

A just culture is one where individuals report errors, near-misses, and safety concerns without fear of blame, while accountability for reckless behavior is maintained. ROV teams often operate in a blame culture — incidents are attributed to the pilot at the controls, investigations end with disciplinary action, and near-misses go unreported because reporting them is career-limiting. This dynamic destroys the most valuable safety information available to the organization. As a supervisor, the most powerful thing you can do is visibly investigate your own errors and near-misses, share what you found, and describe what the team is changing as a result. This models the behavior you are asking others to adopt.

Investigation Best Practices

• Preserve evidence immediately — secure dive log records, video footage, and equipment without alteration before any investigation conversations begin
• Interview witnesses separately before they have had time to align their accounts — early accounts are more accurate than accounts developed after group discussion
• Use open questions in interviews — 'Tell me what happened' produces better information than 'Did you check the tether tension?'
• Include the person most directly involved in the investigation team — their insight is the most valuable, not the least
• Challenge every human error finding — ask what conditions, procedures, or design factors made the error likely or inevitable
• Produce a written investigation report with specific, assigned corrective actions and a defined review date
• Share findings with the full team, including lessons learned — not just corrective actions
• Track the implementation of corrective actions in ThrusterLog or a dedicated action tracking system with completion accountability