To establish an effective and efficient safety program, we must first understand the contributing factors of aviation incidents and accidents. The primary purpose of accident investigation is to reveal the causal factors that led up to the incident or accident and to recommend control measures that will prevent the same type of event to take place again. Dr. James Reason's Accident Causation Model illustrates how latent errors are often times the root cause of aircraft accidents. Reason also hypothesizes that human error is the end result of one or more of five levels of failure, rather than the cause of incidents or accidents. These five levels of failure fall into these fundamental categories:
Decisions-Makers:
- Lack of regulation
- Poorly planned deregulation
- Too rapid expansion of routes or services
- Lip service to safety
Line Management Deficiencies:
- Inadequate procedures
- Poor scheduling
- Neglect of hazards
- Insufficient training
Preconditions:
- High workload
- Undue time pressures
- Acceptance of hazards
- Ignorance of the system
- Fatigued aircrew
Unsafe Acts:
- Omission of checklist item
- Forgetting fuel, equipment or running gear checks
- Use of wrong procedure
- Violation of weather regulations
Defenses Inadequate:
- Warning systems disabled
- Absence of monitoring
- Safety regulations not enforced
- Over-reliance on automation
The models below show us the trajectory of accident opportunity, and the causal sequence of human failures that lead to incidents or accidents.
As safety managers, we have tools available to us to reduce the risks of future aircraft operation, such as causation, 5M, and SHELL Models. Although it would be impossible to completely eliminate risk, if we use these tools in conjunction with each other we can make significant changes that will keep our aviators and passengers safe, with only a minuscule chance for small incidents or catastrophic failures.
Good information
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