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HSG245's first steps are emergency ones: "take prompt emergency action (eg first aid)" and "make the area safe". Then preserve the scene, note who and what was involved, and tell the person responsible for health and safety.
Some events must be reported to HSE under RIDDOR, and HSG245 warns: "Do not wait until you have carried out a thorough investigation before you report it." HSG245 was written in 2004, before the current RIDDOR 2013 rules, so check reportability with our RIDDOR checker or RIDDOR explained rather than the older details in HSG245.
HSE's answer: "It is the potential consequences and the likelihood of the adverse event recurring that should determine the level of investigation, not simply the injury or ill health suffered on this occasion."
So a forklift that missed someone by a metre may deserve more attention than a minor cut, because the worst outcome was far worse. HSG245 describes four levels:
Three kinds of cause (HSG245's terms, which the rest of this guide uses):
Step 1: Gather the information. Start straight away, while memories are fresh and before things are moved. Talk to everyone nearby. Take photos, measurements and a sketch. HSG245 asks, among other things: where and when did it happen, who was involved, what was being done at the time, and "Was there anything unusual or different about the working conditions?" It notes that "Adverse events often happen when something is different."
Step 2: Analyse it. Work out the sequence of events, then the immediate, underlying and root causes. Ask why at each stage. HSG245 is direct about blaming people: "Investigations that conclude that operator error was the sole cause are rarely acceptable." Behind most human errors are conditions that made them likely, such as training, supervision, equipment or layout.
Step 3: Choose the risk control measures. Identify which controls were missing, inadequate or not used, and what would address each cause. Use the hierarchy of controls: a physical change beats a reminder. HSG245 warns that "woolly recommendations" show "the investigation has not delved deep enough".
Step 4: Make an action plan and carry it out. HSG245 asks for actions that are "Specific, Measurable, Agreed, Realistic and Timescaled", fed back into the risk assessment, shared with everyone who needs to know, and followed up. It notes these last steps, "though essential, are often overlooked."
The question is not who made the mistake. It is what made the mistake easy to make.
What happened: at 05:48 on a Tuesday, near the end of the night shift, a picker stepped out of a fire door at the side of the warehouse into the forklift route along the dock. A forklift reversing from a trailer stopped about a metre from them. Nobody was hurt. The forklift driver reported it to the shift supervisor.
Level: medium. Nobody was hurt, but the worst outcome could have been fatal, and the same thing could happen again.
Step 1, facts gathered:
Step 2, causes:
Step 3, controls:
Step 4, action plan:
| Action | Who | By when | Done |
|---|---|---|---|
| Barrier outside fire door (fire adviser to approve) | Site manager | 2 weeks | |
| Decide shelter location or marked route | Site manager | 2 weeks | |
| Update risk assessment and traffic plan for the dock side | H&S coordinator | 3 weeks | |
| Brief all shifts on what changed and why | Shift supervisors | Next shift after barrier fitted | |
| Record "people seen at the fire door" as near misses from now on | All supervisors | Now | |
| Check the door on three night shifts after the change | Shift supervisor | 4 weeks |
HSE's guide HSG245 sets out four steps: gathering the information; analysing the information to find the immediate, underlying and root causes; identifying the risk control measures needed; and making an action plan and carrying it out.
Yes. HSE says the value of investigating each adverse event is the same, because it is often luck that decides whether something becomes a near miss or an accident. The depth of the investigation should depend on the worst potential outcome and how likely it is to happen again.
In HSE's terms, the immediate cause is the most obvious reason an event happened, such as a missing guard. Underlying causes are the less obvious system or organisational reasons, such as checks not being carried out. The root cause is the failing from which the others spring, usually in management, planning or organisation.
It depends on the seriousness. HSG245 suggests a supervisor for minimal-level events, up to a team including managers, H&S advisers and employee representatives, under senior management, for high-level ones. HSE stresses that management and the workforce should both be fully involved.
As soon as possible. HSE says adverse events should be investigated "as soon as possible" because "memory is best and motivation greatest immediately after an adverse event". If a RIDDOR report is needed, make it without waiting for the investigation to finish.
HSG245 was published in 2004 and is still HSE's guide to investigating accidents and incidents. Its RIDDOR details refer to the 1995 regulations, which have since been replaced by RIDDOR 2013, so check reporting rules against HSE's current RIDDOR pages.
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By Hao Zheng, CEO at RoboK · Published 31 October 2026 · Last updated 31 October 2026