Commercial diving incidents are rarely caused by equipment alone. Human factors — fatigue, communication failures, task saturation, and organisational pressures — are primary or contributing causes in the majority of diving accidents. This page covers how human performance affects dive safety and what operations can do to mitigate human error.

Why This Exists

Understanding human factors is essential for designing safe diving operations. Technical knowledge of equipment and procedures is necessary but not sufficient. Supervisors, divers, and managers must understand how human performance degrades under realistic operational conditions.

Who This Is For

  • Diving supervisors responsible for crew performance
  • Safety officers conducting incident investigations
  • Operations managers designing work schedules
  • Trainers developing dive team competency

Fatigue

Sources of Fatigue in Diving

  • Thermal stress — Cold water accelerates fatigue; hot water suits add thermal load
  • Physical exertion — Fighting currents, heavy manual tasks, awkward working positions
  • Long duty cycles — Extended standby and preparation time before in-water work
  • Night operations — Disrupted sleep cycles in continuous operations
  • Travel and time zones — Mobilisation to remote locations

Fatigue and Performance

Fatigued divers exhibit:

  • Reduced concentration and increased error rates
  • Slower decision-making
  • Increased risk-taking
  • Reduced emergency response capability

Operational rule: Fatigue cannot be reliably self-assessed. Supervisors must enforce rest requirements regardless of diver willingness to continue.

Work-Rest Requirements

USN and IMCA guidance requires minimum rest periods between dives and overnight. Dive supervisors must track cumulative work hours and enforce limits.

Communication

In-Water Communication Failures

Voice communications in diving are affected by:

  • Helium speech distortion — Heliox mixtures make speech difficult to understand
  • Mask seal and regulator noise — Background noise masks communications
  • Umbilical routing — Long umbilicals introduce electrical noise
  • Task saturation — Divers may not acknowledge comms while focused on tasks

Requirement: All in-water communications must be logged. The supervisor must confirm diver acknowledgement before issuing safety-critical instructions.

Surface Team Communication

Between the diving supervisor, crane operator, vessel master, and client:

  • Establish clear authority and communication protocols before diving commences
  • Use standard terminology — avoid ambiguous terms
  • Confirm safety-critical instructions with read-back

Task Saturation

Divers working on complex tasks can become task-saturated, failing to monitor gas supplies, track bottom time, or respond to surface communications.

Mitigation:

  • Supervisor tracks all time and gas metrics from the surface
  • Set explicit reminders for gas checks and ascent times
  • Plan tasks to match cognitive load to conditions

Situational Awareness

Situational awareness (SA) is the perception and understanding of the current operational state. Loss of SA is a precursor to most serious incidents.

Factors that degrade SA:

  • Information overload during emergencies
  • Complacency during routine operations
  • Team communication breakdowns
  • Unexpected changes to the dive environment

Organisational Pressures

Production pressures — vessel day rates, weather windows, client timelines — create incentives to continue diving when conditions warrant a pause or abort.

Supervisory authority: The diving supervisor has the authority and responsibility to halt diving at any time for safety reasons. This authority must be explicitly protected by management and cannot be overridden by client or commercial pressure.

Crew Resource Management (CRM)

CRM principles from aviation apply directly to diving operations:

  • Briefings — Pre-dive briefing ensures shared understanding of the plan
  • Challenge and response — Any team member can raise a safety concern
  • Closed-loop communication — All instructions are confirmed with read-back
  • Post-dive debrief — Identify what went well and what could be improved

Incident Causation Models

Reason’s Swiss Cheese Model

Accidents occur when holes in multiple defensive layers align:

  • Equipment failures, procedure violations, supervisory lapses, and organisational failures combine to allow an accident

Bow-Tie Analysis

Links hazard → top event → consequences, with barriers on each side. Human factors affect both threat barriers (preventing the top event) and recovery barriers (limiting consequences).