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The Safety Analysis Methodology
EHEST Conference13 October 2008
Cascais, Portugal
The Safety Analysis Methodology 2
Contents
Introduction on Approach and Scope of the analysisAnalysis MethodologyExample
The Safety Analysis Methodology 3
General Process
Reviewoccurrences
Develop Safety Action Plans
Implement Safety Action Plans
Monitors
The Safety Analysis Methodology 4
General Process
Reviewoccurrences
Develop Safety Action Plans
Implement Safety Action Plans
MonitorsSafety Analysis Team
(this presentation)
The Safety Analysis Methodology 5
Maintain international compatibility
Reviewing accidents using a standard
method adapted by IHST from CAST (US
Commercial Aviation Safety Team)
Format allows comparison with data
from the US and other regions
Approach
The Safety Analysis Methodology 6
Scope of analysis
Based on a data driven approach
Focus on:
Accidents (definition ICAO Annex 13)
Date of occurrence year 2000 - 2005
State of occurrence located in Europe For this purpose Europe is defined as the EASA Member States
(27 EU + plus Iceland, Liechtenstein, Norway and Switzerland)
Only those accidents are being analysed where a final report from Accident Investigation Board is available
The Safety Analysis Methodology 7
Analysis Methodology
1. Collect general occurrence information from accident report
4. Produce Intervention Recommendations (IR)
3. Assign standard codes to factors Standard Problem Statements (SPS)
from IHST taxonomy and HFACS
2. Describe and analyse the accident Identify events (what happened)
and factors (why it happened) in free text
The Safety Analysis Methodology 8
Process manual and tool
The Safety Analysis Methodology 9
1. Collect general occurrence information
From accident reportsIncludes:
Occurrence Date and State of OccurrenceAircraft Registration and Aircraft TypeType of OperationAircraft Damage and Injury LevelPhase of FlightMeteorological ConditionsPilot and co-pilot flight experience Etc.
The Safety Analysis Methodology 10
Accidents are broken down into an event sequence
The method requires describing, in free text:
What happened (events and conditions)
Why these happened (factors)
The analysis uses the expertise and experience of the regional teams
2. Describe and analyse the accident
The Safety Analysis Methodology 11
Three models used to assign codes1. Standard Problem Statements from IHST taxonomyAnd additionally, for a more thorough description of human factors2. Human Factors Analysis and Classification System (HFACS) by Wiegmann and Shappell, US DoT, February 20013. HFACS Maintenance Extension by US Naval Aviation
3. Assign standard codes to factors
The Safety Analysis Methodology 12
Standard Problem Statements from IHST taxonomy
Over 400 codes in 14 different areas
3. Assign standard codes to factors
Ground duties Part/System Failure
Safety Management Mission Risk
Maintenance Post-crash survival
Infrastructure Data issues
Pilot judgment & actions Ground personnel
Communications Regulatory
Pilot Situation awareness Aircraft Design
The Safety Analysis Methodology 13
Example Standard Problem Statements
3. Assign standard codes to factors
The Safety Analysis Methodology 14
HFACS by Wiegmann and ShappellOver 170 codes in 4 main areas to code human factors in detail
3. Assign standard codes to factors
Organisational Influences
Unsafe Supervision
Preconditions for Unsafe Acts
Unsafe Acts
The Safety Analysis Methodology 15
3. Assign standard codes to factors
Unsafe Acts
Errors Violations
Routine violationsExceptional violations
Decision errorsSkill-Based errorsPerceptual errors
The Safety Analysis Methodology 16
3. Assign standard codes to factors
Preconditions
Environmental Factors
Condition of Individuals
Personnel Factors
The Safety Analysis Methodology 17
3. Assign standard codes to factors
Supervision
Failure to Correct Known Problem
Planned Inappropriate
Operations
Inadequate Supervision
Supervisory Violations
The Safety Analysis Methodology 18
3. Assign standard codes to factors
Organisational Influences
Resource Management
Organisational Climate
Organisational Process
The Safety Analysis Methodology 19
Example HFACS codes
3. Assign standard codes to factors
The Safety Analysis Methodology 20
3. Assign standard codes to factors
HFACS Maintenance Extension (HFACS ME)
The Safety Analysis Methodology 21
Analysis Methodology
1. Collect general occurrence information from accident report
4. Produce Intervention Recommendations (IR)
3. Assign standard codes to factors Standard Problem Statements (SPS)
from IHST taxonomy and HFACS
2. Describe and analyse the accident Identify events (what happened)
and factors (why it happened) in free text
The Safety Analysis Methodology 22
For every coded factor one or several Intervention Recommendations can be suggested
AIB recommendations are includedWill be used at a later stage by the implementation team to generate Safety Action Plans
4. Produce Intervention Recommendations
The Safety Analysis Methodology 23
Assessment of confidence in factors and recommendations
SPS/HFACS are scored between 0-4 on:
Validity: Quality and credibility of information
(documented evidence versus expert judgment)
Importance: Contribution to the accident
IR are scored between 0-4 on:
Ability: Capability of an IR to mitigate an event
Usage: Confidence that an IR will be utilised and
will perform as expected
Will be used at a later stage by EHSIT
The Safety Analysis Methodology 24
Occurrence categories
Used to classify occurrences at a high level to permit analysis of the data in support of safety initiatives
Future developments based on existing internationally agreed taxonomy
Example:Share of Occurrence Categories (Top 7) in Accident Data Set
0 5 10 15 20 25 30 35 40
External Load
System/Component Failure - Powerplant
System/Component Failure - Non Powerplant
Controlled Flight into Terrain
Low Altitude Operations
Collisions during T/O and landing
Loss of Control - In Flight
Oc
cu
rre
nc
e C
ate
go
rie
s
Percentage %
The Safety Analysis Methodology 25
Analysis Example
The Safety Analysis Methodology 26
Thank you for your attention
Questions?
European Helicopter Safety Team
EHEST
The Safety Analysis Methodology 27
ANNEXEHSAT Analysis Tool
The Safety Analysis Methodology 28
Process manual and tool
The Safety Analysis Methodology 29
HFACS SPS taxonomy
Human Factors Analysis and Classification System (HFACS) D.A. Wiegmann and S.A. Shappell
Process manual and tool
Recommended