How to Carry Out an Accident Investigation

8 minute read | 08 July 2019 12:00:00 BST

Accidents at work need effective investigationAccident investigation and analysis of work-related accidents and incidents form the foundation of a good safety culture. It is an essential part of the management of health and safety. Learning lessons from experience is vital in making the workplace safer and avoiding further pain, suffering and grief.
If it is a serious life changing or a fatal accident the ripple effect is huge. It extends to the immediate family and friends, to fellow workers and beyond. I will offer some guidance on the key steps to take when carrying out an investigation of an incident or accident

Golden rules to accident investigation

There is an old joke in the world of safety that the real reason for conducting an accident investigation is to establish who to blame. Unfortunately, there are still some companies that still adopt a blame culture. This is very unhelpful in accident prevention. It creates a poor safety culture and under reporting of accidents.

The golden rules when dealing with an accident are:

  • Look after the victim
  • Make safe the area
  • Carry out the accident investigation
  • Notify the enforcing authority if the accident falls under the notification criteria. This will depend on where you live

Root causes of accident investigation

The root causes in the number of accidents that I have investigated fall into two categories:

  1. Failures in the Safety Management System 
  2. Failures by line managers in enforcing the rules

It is important to have an open mind; always base your decisions on fact, not emotion, rumours or assumptions.

Resources needed to carry out the investigation

Have a bag ready for an accident investigation. The resources you require will depend on where you work i.e. construction site, office, warehouse, the industry you work in and potential hazards present. Typically the items that I have included are:

  • Site plans
  • Torch (with spare batteries) a roll of hazard warning tape, measure tape, a travel first aid kit
  • Camera or mobile phone to take photos and videos and charger
  • Printed paper copies of witness statement forms
  • Up to date phone list and organisational chart, note pad and pen
  • Measuring and hazard warning tape
  • Suitable personal protective equipment: hi-visibility vest, safety boots, hard hat, safety glasses, gloves depending on what chemical hazards there may present (oils etc.), dust mask,

Immediate response actions to take when accident occurs

When you are notified of any accident, follow these guidelines:

  • Make sure the injured person has all the medical assistance that they need

Gather the basic facts about:

  • Details of the injured parties and injury
  • Time and location
  • Activities undertaken
  • Workplace layout and materials
  • Unusual working conditions
  • Whether the risk was known or not
  • Whether a Safe System of Work existed and was being followed
  •  Levels of competence

Actions to be taken

  • Inform the Enforcement Agency (this depends on the country where the accident happened)
  • Find out who the witnesses are; separate them so they do not influence one another
  • Arrange to be escorted to the accident if required
  • Follow the site sign in rules
  • Secure the accident site; block it off to prevent people moving anything etc.

Gathering the facts

There are three main techniques to gather the facts: observation, interview and documentation.


Get to the scene of the accident as soon as you have been notified. Taking photographs is the best way to visually record the scene of the accident. When you are taking images of items relevant to the accident remember to show the scale and size; for example if it is a small object place an everyday item next to it such as a pen for a large object ask someone stand next to it. This helps to understand the scale of the items clearly. Label these relevant items.
Make notes about the photographs as you take the pictures. These simple prompt notes will help you and any other relevant people such as the enforcing authority when you get back to your office when compiling your report

Setting up the interviews
Find and book suitable meeting room(s) to conduct accident investigation interviews. When you send out the invite to the interview, reassure the person that this is the normal procedure and ask them if they wish to bring colleague or Trade Union representative. To prevent any disruption put up a ‘do not disturb accident investigation meeting’ notice.


Treat everyone with respect and dignity. Explain the purpose of the investigation meeting and inform them that you will be taking notes to make sure that you have recorded everything that is said accurately. Put the person at ease: offer them a drink. Try to be relaxed in your approach and if other departmental managers are assisting you get them to introduce themselves and state their role and purpose in the meeting.

You may find it useful to have a flip chart in the room. You can draw a rough layout of the work area showing where the accident happened “x” marks the spot. This is a simply and clear presentation of the facts and it will make it easier for the people being interviewed to give accurate information. When under pressure some people can get left and right, north and south easily confused.

During the interview use open questions (where the answer is not yes or no) to get an understanding of what happened. Open questions are used to get the person to open up to you to explain what they know about the accident. For example:

  • “Explain to me what you saw at the time of the accident”
  • “What were the lighting levels in the warehouse at the time of the accident?”
  • “What in your opinion could have prevented the accident?

This will help to focus just on the facts.

A number of people who witness the same accident will interpret it differently. Therefore, record the different points of view of what happened. Remember, you need to reflect on the facts and not the opinions from the interviews. Look at all the sources of evidence to see if they endorse what has been said.


Typical documentation that you will look at during any investigation are : Risk assessments, Safe Systems of Work, Permits to Work, Method statements, Training records, Work procedures/Job Guides Previous Accidents in the work area, Near Miss reports , and previous Audits. Depending on the type of accident, you will also examine things like pre use check sheets, workplace inspections, statutory test certificates and medical records to establish if the person was on restricted duties.

Tools to understand why accidents happen

There are effective tools and techniques to help you understand what the root cause of the accident was. Accident investigation techniques are essential. For example if your investigation shows that the operator is solely responsible for the accident, it is very probable that you have not gone into sufficient detail in all the circumstances and different causes. We know that in the majority of casesit would not be the operator’s fault. The operator had probably been set up to have the accident by poor communication, misplaced motivation or pressure by the management

Domino effect tool

Using a tool such as the domino effect below will help you to look at the sequence of events leading to the accident. 

Root causes of accidents


A tool that I prefer to use to help focus my attention is the multi-causal theory. It pushes you to ask the very basic questions for example, ‘why did the operator perform that action?’ An example is shown below:

Multi-causal tool

By adopting this method, we have discovered the root causes of the accident were:

  1. Lack of instruction and supervision  
  2. Poor planning
  3. Poor safety culture in that area
  4. Poor working environment (lack of space)
  5. Lack of breaks

The process of investigating accidents will help you to learn from experience. By analysing the information, you can identify suitable risk control measures, prevent similar events recurring and share your learning. These tips will enable you to reduce the root causes of accidents and create a safer working environment where people and companies can work effectively.

Tags: Advice for businesses & organisations, Advice for learners

Chris Pollington CMIOSH

Chris is a Health and Safety consultant who has been working in the industry since 1995. His background includes production management and construction safety, with particular experience in CDM.