29 April 2008 CASS 2008
Just a Piece in a Jigsaw Puzzle …
Systems Dynamics and Safety in Canadian Aviation
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Overview
What is a system?How does it work?Why does it fail?
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What is a System?
Nested decision-making
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The WorkspaceThe Workspace
The CrewThe Crew
Constraining ActivityConstraining Activity
The Environment
Commercial ActivityCommercial Activity
What is a System?
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Activity at the level of ‘Production’
PressureMax Temperature
Min
Conditional <79% N1
Continuous <94% N1
Continuous
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PPPP
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PPPPPrivate Processing + Public Performance
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PPPPPrivate Processing + Public Performance
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PPPPPrivate Processing + Public Performance
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Task: Arrange 11 trees,To be planted in 6 rowsEach row to contain 4 trees
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Task: Arrange 11 trees,To be planted in 6 rowsEach row to contain 4 trees
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Activity at the level of ‘Organization’
Aircraft 1 Aircraft 2
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GroundController
TowerController
BN2 DHC-8
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OSTC
Operations
POI
CBAD
Certification
Province of Ontario
Operator
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OSTC
Operations
POI
CBAD
Certification
Province of Ontario
Operator
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OSTC
Operations
POI
CBAD
Certification
Province of Ontario
Operator
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OSTC CBAD
Certification Operations
POI
Province of Ontario
Operator
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OSTC CBAD
Certification Operations
POI
Operator
Province of Ontario
?
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ExploitationPlanningDeicing
FacilitationCertification
Oversight
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S
P
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A
BP C
S
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Production
• Technology• Procedures• Pilot ‘Knowing’
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Representation of Information
Normal
(Green)
1173
1071
1020
660
RPM
Fuel Cut-off
Caution(Amber)
Max (Red)
Over-limit
1064 Overspeed Governor
Indication System
Condition Lever
PEC
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Pilot’s Construction of Risk
• Feather Prop v Engine Shut down• No red lines• Situation stable• Viewed as technical problem, not an
operational problem
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What the Safety Management System Said
Risk: If the event happens again the probability of a major accident is not increased or increased only under extreme circumstances
Seriousness: On this occasion the probability of a major accident was not increased but the event was indicative of a quality problem that could affect safety
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System Dynamics
• Normalization of Deviance• Asynchronicity
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System Dynamics
• Normalization of Deviance• Asynchronicity
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Manufacturer
Operator
Authority
AOM
QRH
OM pt ‘B’
AFM
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System Dynamics
• Normalization of Deviance• Asynchronicity
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Conclusion
• Individuals act to create solutions to operational problems in real time
• Individuals act in a context driven by systems dynamics
• Safety is a product of people, not organizations
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And finally …
Strategic decisions shape behaviour
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And finally …
Strategic decisions shape behaviour
…but maybe not in the way you’d planned!
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Thank you for your attention
Norman MacLeod