A Part 21 Accident Investigation
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Transcript of A Part 21 Accident Investigation
ACCIDENTS
Causation, Reporting & Investigation
Causation Theories
Single Cause Domino Theory
Multiple Causation
Single Cause Domino Theory
Heinrich’s theory
Each factor is the fault of the factor that
immediately precedes it
A preventable injury is the natural culmination of
a series of events or circumstances, which occur
in a fixed logical order
Single Cause Domino Theory
Ancestry & Social
Environment
Fault of Person Unsafe Act or
Condition
Accident Injury
Single Cause Domino Theory
If one of the dominoes is removed then the
chain of events will be halted, and the accident
will not happen
Element 3 (unsafe act and/or mechanical or
physical hazard) is probably the easiest factor
to remove
Single Cause Domino Theory
Bird & Loftus extended Heinrich’s theory to encompass the
influence of management in the cause & effect of accidents
They suggested a modified sequence as follows:
Lack of management control, permitting
Basic causes (personal & job factors), leading to
Immediate causes (substandard practices or conditions), which are the
direct cause of
The accident, which results in
Loss (negligible, minor, serious or catastrophic
This modified sequence can be applied to every accident and is
of basic importance to loss control management
Multiple Causation
May be more than one cause, not only in
sequence, but occurring at the same time
In accident investigation all causes must be
identified
Usually simple accidents have a single cause
Major disasters normally have multiple causes
Multiple Causation
Cause a
Cause b Unsafe Act
Cause c
Accident
Injury or
Damage
Cause d
Cause e
Unsafe
Condition
Cause f
Unsafe Acts
Categories:
Operating without clearance
Operating at unsafe speed
Rendering safety devices inoperative
Using unsafe equipment, or using it unsafely
Unsafe methods e.g. loading, carrying, mixing
Adopting unsafe position or posture
Working on moving or dangerous equipment
Horseplay e.g. distracting, teasing, startling
Failure to wear PPE
Lack of concentration; fatigue or ill health
Human Factors
Unsafe Acts
Unsafe acts can be active or passive:
Active Unsafe Acts:
Worker deliberately removes machine guard
Passive Unsafe Acts:
More difficult to deal with
By pursuing an active safety policy, it is possible to achieve a
reduction in bad habits and hence accidents
Unsafe Conditions
Categories:
Inadequate guarding
Unguarded machinery
Defective, rough, sharp, slippery, decayed, cracked surfaces
Unsafely designed equipment
Poor housekeeping, congestion
Inadequate lighting, glare, reflections
Inadequate ventilation, contaminated air
Unsafe clothing or PPE
Unsafe processes
Hot, humid or noisy environment
Unsafe Acts/Conditions
The picture shows how unsafe acts & conditions may interact to produce an
accident. Accident potential is increased when unsafe acts & conditions occur
simultaneously. Of course, this is not to say that an act or condition alone
could not result in an accident.
Unsafe Acts Unsafe
Conditions
Acc
iden
t
Pote
nti
al
Accident Reporting
Information should be kept for all injuries, and
preferably for near misses
The safety practitioner needs to design a
suitable form to ensure that he gets the
information that he needs for investigations
Accident Investigation Records
Format: Name & personal details of victim
Date, day and time of accident
Location of accident
Occupation of victim
Job being done at time
Nature of injury or damage
What inflicted the injury or damage
Who had control of the cause of the injury or damage
What actually happened
Basic and immediate causes
Immediate remedial action taken
Recommendations to prevent recurrence
Use of Investigation Records
Accident records are useless if they are used only to count accidents.
Detailed and thorough study of the records as part of the normal
ongoing accident prevention programme should yield the following
useful information:
Relative importance of the various injury & damage sources
Conditions, processes, machines and activities which cause the
injuries/damage
The extent of repetition of each type of injury or accident in each
operation
Accident repeaters, I.e. those workers who tend to be repeatedly injured
or are involved in more accidents
How to prevent similar accidents in future
Accident Investigation
Could be carried out by:
Safety Practitioner
Management or Supervisor
Safety Representative
Inspector
A joint investigation by company/safety rep is often a good idea
An investigation which does not discover what went wrong, and
produce some useful information and recommendations for
corrective action, is just a waste of time
Accident Investigation
Initial Actions
Questioning the victim
Treatment of victim is first priority
Immediate questioning may not be possible - they should be allowed to
collect their thoughts and control their nerves
Witnesses & Conditions
Investigator can usually go to accident scene and get a fairly complete
story from on-site conditions and witnesses
In all serious accidents and in all other cases where practicable,
conditions at accident scene should remain undisturbed until
investigation is complete
Investigators
Immediate supervisor:
Likely to know most about the situation
Knows his own people better than anyone
Has personal interest in determining causes, as
accidents affect the efficiency and morale of his
department
Familiarity with staff could cause problems
Investigators
Recognising Hazards
Familiarity with plant, equipment and layout of operations will assist
in recognising hazards that have been overlooked for some time
Unsafe acts, as well as conditions, contribute towards most
accidents
It is not sufficient merely to recommend fitting a guard while
overlooking the unsafe act, such as rendering the guard ineffective
or placing hands in the danger zone
It is also insufficient to limit attention to an unsafe act if fitting a
better guard would reduce the likelihood of injury
Investigators
Safety Practitioner
Necessary in more serious cases
Supervisor may not have necessary authority
Should seek assistance from local supervisor
Investigator must have authority to go as far as is
necessary to get to the cause of the problem
The Investigation
Promptness
As soon as possible after the event
Facts will be easier to determine and more details will be
remembered by those involved
Fire
Helpful if investigator is present during the fire
Investigator may gain useful information by watching the
activities of firemen
The Investigation
Evidence
Depending on severity of any injuries or damage,
investigator should be present during clear-up and
reinstatement as valuable clues may otherwise be
missed
Failing which, supervisor should take it upon himself to
collect the necessary evidence
The Investigation
Equipment
Photographic equipment
Portable lights (electricity may be switched off or accident scene may be
poorly lit)
Sketchpad, pencils and measuring equipment
Record-keeping equipment e.g. notebook and cassette recorder
Sample collection equipment e.g. jars, paper bags, cartons etc.
Tools for cleaning debris or spillages should also be available
Portable gas/vapour detecting equipment
Accident Investigation Procedure
1. Inspection of the accident scene to collect any information
relating to physical conditions of the plant, equipment and
building
2. Interview witnesses and others likely to give information
concerning any unsafe acts or conditions which may have
contributed to the accident
3. Summarise all available evidence accurately in a written
report to management, recommending future actions to
prevent a recurrence
Inspection of the Scene
Careful, detailed look at accident scene, evaluating and noting
the following:
Extent & severity of damage
Damage to surrounding property
Environmental conditions which may have had some bearing
on the accident, such as temperature, ventilation, humidity
and illumination
Survey the accident scene to see if there are any obvious
dangerous physical conditions which may have been
responsible for the accident
Inspection of the Scene
In the case of spillages, splashes or other escapes of
poisonous, explosive, flammable or other dangerous material, it
may be necessary to take samples for subsequent investigation
Where machinery or other equipment has been involved, it may
be necessary to issue instructions prohibiting the use or repair
of it until the investigation has been completed
Talking with On-Site Personnel
Easy to upset people when asking questions about what has
been done, or what has not been done
Casual remarks made during the site inspection may be quite
revealing and the investigator should continue to talk to any
personnel involved near the scene of the accident
This would also serve as an ideal opportunity to explain the
object of the exercise is to discover and root out the causes so
as to prevent a repetition. It is not to apportion blame or to
criticise any individual
Interviewing Witnesses
Types of Witness
Primary witness
The victim
Secondary witness
Extremely rare, the eyewitness
How many people really see the instant of an accident?
Tertiary witness
Can offer variety of corroborative statements regarding the acts of
people or environmental
Interviewing Witnesses
Putting witnesses at ease
Explain fully purpose of investigation
Encourage participation and involvement
Show interest in any ideas they might have about possible
preventive measures
Witness must be assured that the purpose of the
investigation is not to blame anyone, but to attempt to find out
the cause and thereby reduce possibility of a recurrence
Interviewing Witnesses
Interview Location
Best to carry out interviews at scene of accident, as it
is easier for those involved to communicate effectively
with “props” close to hand
Easier to explain what happened if witnesses are able
to point out specific things and recall their actions
related to specific locations
Interviewing Witnesses
Question Phrasing
Open ended question - what, where, when, how or who
Questions starting with why may put witness on the defensive
Typical questions: What happened? What did you see?What time was it?
Where were you at the time? Where was the victim?
When did you realise something was wrong?
How did it happen? How were you involved?
How could it have been prevented?
Who else was involved? Who else saw it? Who reported it?
Interviewing Witnesses
Attitude “What happened” will often promote the fullest response and it is vital the
investigator listens, without interruption, to the witness’s account of the
accident
If something is not understood, investigator should wait until witness has
completed his account before asking for clarification
Do not disagree with any of witness’s statement or make any judgements
on his evidence alone
What a witness believes to have happened will depend to some extent on
just how he perceived the situation, even though this might conflict with
the actual facts
Interviewing Witnesses
Conclusion
When witness’s account of accident has been heard,
investigator should repeat it to witness to ensure account is
fully understood
Interview should be concluded on a positive note, which is
best achieved by discussing any ideas he may have
regarding prevention of a similar occurrence - this will serve
to reaffirm the purpose of the interview and ensure the
witness’s further co-operation, should it be needed
Interviewing the Victim
Ideally first to be interviewed
Injuries may be serious, or may be suffering
from shock
Should be interviewed at the earliest
opportunity
General principles for interviewing witnesses
apply
What Should be Investigated
ALL incidents/accidents should be investigated
Purpose is to find the cause, with the intention
of preventing a recurrence, rather than
apportioning blame
An injury usually involves some degree of blame
falling on management, supervision, victim or
workers