NEBOSH Incident Investigation 3

Question 1

What immediate and underlying causes might be identified when investigating a worker who fell from a ladder?

Accepted Answer

Immediate: the ladder was damaged/improperly positioned; Underlying: lack of ladder inspection regime, inadequate work-at-height risk assessment, or insufficient training in ladder use

Answer

A thorough investigation distinguishes between immediate causes (the direct physical events — damaged equipment, poor positioning) and underlying causes (the management system failures — no inspection programme, inadequate risk assessment, poor training). Addressing only immediate causes treats symptoms; root cause analysis addresses the systemic failures that allowed the situation to develop.

Question 2

Under RIDDOR 2013, what constitutes an 'over-7-day incapacitation' that must be reported?

Accepted Answer

When a worker is incapacitated for more than 7 consecutive days (not counting the day of the accident) from carrying out their normal work duties as a result of a work-related injury

Answer

An over-7-day incapacitation is reportable when a worker is unable to carry out their normal work duties for more than 7 consecutive days (excluding the day of the accident) as a result of a work-related injury. This must be reported within 15 days of the accident. The incapacitation does not have to be absence from work — inability to do normal duties is sufficient.

Question 3

How does the Swiss cheese model explain why multiple safety barriers sometimes fail simultaneously?

Accepted Answer

Because each defensive layer has latent weaknesses (holes) that are normally offset by other layers, but organisational factors, complacency, or unusual conditions can cause the holes to align temporarily, allowing a hazard to penetrate all defences

Answer

Each layer of defence has latent conditions (dormant weaknesses) created by organisational factors such as time pressure, budget cuts, poor communication, or inadequate training. Normally, even if one layer fails, others catch the hazard. But when organisational pressures or unusual circumstances cause multiple weaknesses to align simultaneously, the hazard passes through all layers.

Question 4

What type of evidence should be gathered during an accident investigation?

Accepted Answer

Physical evidence (scene preservation, photographs, equipment), documentary evidence (procedures, training records, risk assessments, maintenance logs), and testimonial evidence (witness statements, expert opinions)

Answer

A thorough investigation gathers three types of evidence: physical (preserving and photographing the scene, examining equipment, collecting samples), documentary (reviewing relevant procedures, training records, risk assessments, maintenance records, previous incident reports), and testimonial (interviewing witnesses, the injured party, supervisors, and consulting technical experts).

Question 5

In a 5 Whys analysis, a worker suffered a chemical burn. The sequence revealed: Why burned? No gloves worn. Why no gloves? None available. Why none available? Not ordered. Why not ordered? No reorder system. Why no system? No one assigned responsibility. What is the root cause?

Accepted Answer

A management system failure — no one was assigned responsibility for maintaining PPE stock levels, meaning there was no system to ensure availability

Answer

The 5 Whys traced the cause from the immediate event (burn) through proximate causes (no gloves, none available, not ordered) to the root cause: a management system failure where responsibility for maintaining PPE stock was never assigned. This root cause is actionable — assigning responsibility and implementing a reorder system prevents recurrence.

NEBOSH IGC Practice Test

NEBOSH IGC Practice Test

NEBOSH Incident Investigation 3