Lessons Learned from TSB Investigations of Helicopter Accidents (1994-2003)

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Lessons Learned from TSB Investigations of
Helicopter Accidents (1994-2003)
Transportation Safety Board of Canada
Bureau de la sécurité des transports du Canada

• Joel Morley and Brian MacDonald
• International Helicopter Safety Symposium
• Montreal, QC
• September 26-29, 2005

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Introduction

• Average of 53 Canadian registered helicopters
  involved in accidents each year (range of 44 to
  68)
• 9.3 accidents per 100 000 flight hours

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Method

• Employed sample of occurrences investigated by
  TSB (N103)
• Comparison sample of military occurrences
  investigated (N37)
• Categorized by a team of TSB investigators (4
  step process)

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Step 1 Initial Occurrence Categorization

• Power Loss
• Structural Failure
• Loss of Visual Reference
• Struck Object
• Loss of Control
• Loss of Separation
• Training for Emergencies
• Other

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Step 2 Examination of Proportion of Fatal to
Non-Fatal Accidents

• To see where greatest human cost was occurring
• Determined
• Number of accidents in each category which were
  fatal (1 or more fatality)
• Number of lives lost in each category

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Step 3 Further Break-down of Occurrence
Categories

• Examined types of events contributing to
  occurrences
• Selected sub-categories which seemed to capture
  these factors
• Loss of separation, training for emergencies
  and other not sub-categorized

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3(a) Power Loss
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3(b) Structural Failure
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3(c) Loss of Visual Reference
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3(d) Loss of Control
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3(e) Struck Object
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Step 4 Conclusions from Analysis
What does this mean to me??
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Conclusions Loss of Visual Reference Accidents

• 3 in frequency, 1 in human cost
• 80 fatal with a total of 31 lives lost
• Civil helicopter flying largely VFR
• Possible counter-measures
• Awareness
• Capability
• Technology

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Conclusions Power Loss and Structural Failure
Accidents (1)

• Together account for 52 of sample
• Improper maintenance 2nd most frequent
  sub-category in both
• Underscores importance of efforts to understand
  and mitigate the factors underlying maintenance
  error such as
• Improved maintenance procedures
• Awareness training

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Conclusions Power Loss and Structural Failure
Accidents (2)

• Power loss is most heavily populated category but
  produced the fewest fatal accidents
• Training to handle power failures effective
• Multi-engine helicopters also represented in
  power loss accidents

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Conclusions Loss of Control Accidents

• Well recognized hazards
• Loss of tail rotor effectiveness
• Decayed rotor RPM
• Dynamic roll-over
• Vortex ring state
• Environmental
• Flight Control Obstruction
• Efforts to address these hazards need to be
  maintained

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Conclusions Struck Object Accidents

• All hazards represented well known
• Potential counter measures could include
• Raising awareness
• Revising procedures
• Training in risk management

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Conclusion
We need to devote resources to

• Snapshot of accidents investigated
• Hope it will help drive safety management
  practices

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Questions???