40 Questions
What is the central factor in preventing incidents, according to Heinrich?
Unsafe acts and unsafe conditions
What is the result of a series of events or circumstances, according to Heinrich?
A preventable injury
What is an example of an underlying cause, according to Heinrich?
Inadequate supervision
What is the name of the theory that explains the sequence of events leading to an accident?
Heinrich's Domino Theory
What is an example of an accident, according to Heinrich?
Striking of persons by flying objects
Why do people commit unsafe acts, according to Heinrich?
Due to all of the above
What is the main idea behind Heinrich's Domino Theory?
Accidents can be prevented by eliminating unsafe acts and conditions
What is a direct cause of an accident, according to Heinrich?
A worker who is not convinced that a preventative measure is necessary
What is the Snook theory used to explain?
How systems' baseline performance drifts away from their original design
What is considered during the early stages of system design to recognize performance limitations and hazards?
Operational interactions between people and technologies
Why does Snook argue that practical drift is inevitable?
Because no matter how careful and well thought out the design, drift is inevitable
What is an example of a reason for practical drift?
Changes to the system, including new components
What is the fourth component of the SHELL Model?
Not specified in the given information
What is the central component of the SHELL Model?
The human (at the center)
What does the SHELL Model illustrate?
The relationship between humans and the workplace components
What is the purpose of considering operational interactions during system design?
To recognize the anticipated performance limitations as well as possible hazards
What does the term 'Machine' refer to in the context of aviation?
The design, manufacture, maintenance of aircraft and engineering reliability/performance of equipment
What is the primary focus of the 5-factor model in aviation?
Supervisory capacity of management
What is the difference between an error and a violation in aviation?
An error is unintentional, a violation is deliberate
What is the goal of reduction strategies in aviation?
To reduce or eliminate factors contributing to errors
What is an example of a slip in aviation?
Operating the flap lever instead of the gear lever
What is the purpose of capturing strategies in aviation?
To assume the error will be made and minimize consequences
What is a mistake in the context of aviation errors?
A failure in the plan of action
What is the main difference between lapses and slips in aviation?
Lapses are memory failures, slips are action failures
What does the term 'Liveware' refer to in the context of the SHELL Model?
Other humans in the workplace
What is the primary focus of the SHELL Model?
The humans at the front line of operations
What are the '4 Ps' of human performance referred to in the SHELL Model?
Physical, Physiological, Psychological, and Psychosocial factors
What is the Liveware-Hardware (L-H) interface concerned with?
The relationship between humans and physical attributes of equipment and facilities
What is the Liveware-Software (L-S) interface concerned with?
The relationship between humans and supporting systems in the workplace
Why is the human factor at the center of the SHELL Model considered the least predictable?
Because humans are susceptible to internal and external influences
What is the purpose of considering the '4 Ps' of human performance in the SHELL Model?
To consider human factors as an integrated part of SRM
What is the main benefit of considering the Liveware component in the SHELL Model?
To consider the importance of human factors in system design
What does national culture differentiate among nations?
The role of the individual, authority distribution, and national priorities
What is a simple definition of safety culture?
An organizational commitment to safety at all levels of operation
What is the primary goal of a positive safety culture?
To create an atmosphere where employees are aware of risks and avoid unsafe actions
What is the focus of Westrum's typology in 1988?
The flow of information in an organization
What is the name of the first stage of Hudson's safety culture maturity model?
Pathological
What is the characteristic of a Pathological organization?
It cares less about safety than about not being caught
What is the primary difference between a Reactive and a Generative organization?
Their approach to safety management
What is the purpose of a safety culture?
To create an atmosphere of safety awareness and commitment
Study Notes
Heinrich's Domino Theory
- Heinrich's domino theory defines the direct cause of incidents as unsafe acts and/or unsafe conditions
- Heinrich believed that these factors were the central cause of incidents and the easiest to remedy
- He defined four reasons why people commit unsafe acts:
- Improper attitude
- Lack of knowledge or skill
- Physical unsuitability
- Improper mechanical or physical environment
- He later subdivided these categories into "direct" and "underlying" causes
Accidents
- Heinrich defines accidents as events that cause injury, such as falls or striking of persons by flying objects
- He believes that accidents are the natural culmination of a series of events or circumstances that occur in a fixed and logical order
The Practical Drift
- The practical drift refers to the gradual deviation of a system's performance from its original design
- Snook contests that practical drift is inevitable in any system, no matter how careful and well thought out its design
- Reasons for practical drift include:
- Technology that does not operate as predicted
- Procedures that cannot be executed as planned under certain operational conditions
- Changes to the system, including the addition of new components
- Interactions with other systems
- Safety culture
- Adequacy (or inadequacy) of resources
The Shell Model
- The Shell Model illustrates the relationship between humans and workplace components
- The model consists of four satellite components:
- Software (S): procedures, training, support, etc.
- Hardware (H): machines and equipment
- Environment (E): the working environment
- Liveware (L): other humans in the workplace
- The model emphasizes the need to consider human factors as an integrated part of Safety Risk Management (SRM)
- The "4 Ps" of human performance are:
- Physical factors (strength, height)
- Physiological factors (health, stress, etc.)
- Psychological factors (motivation, judgment, etc.)
- Psychosocial factors (personal issues or tension, etc.)
Human Factors
- The Liveware-Hardware (L-H) interface refers to the relationship between humans and the physical attributes of equipment, machines, and facilities
- The Liveware-Software (L-S) interface refers to the relationship between humans and supporting systems found in the workplace
The 5-Factor Model
- Management: refers to supervisory capacity of management in terms of regulations, policies, attitudes towards safety
- Mission: refers to the type of task implemented, whether it was complex or routine
Errors and Violations
- An error is an unintentional action or inaction that leads to deviations from organizational or individual intentions or expectations
- A violation is a deliberate act or omission to deviate from established procedures, protocols, norms, or practices
- Slips are actions that do not go as planned, while lapses are memory failures
- Mistakes are failures in the plan of action
Safety Culture
- National Culture: differentiates the characteristics of particular nations, including the role of the individual within society, how authority is distributed, and national priorities
- Safety Culture: an organizational commitment to safety at all levels of operation
- Positive Safety Culture: where everyone is aware of their roles concerning safety and all in the organization are truly committed to safety
- Safety Culture Maturity:
- Pathological: the organization cares less about safety than about not being caught
- Reactive: the organization looks for fixes to accidents and incidents after they happen
- Hudson's five stages of safety culture maturity
This quiz covers Heinrich's domino theory, focusing on the third domino, which deals with the direct cause of incidents, including unsafe acts and conditions. Learn about Heinrich's approach to preventing incidents.
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