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CAST - Causal Analysis using System Theory (CAST):

Implementation and Integration

Presented by: Darren Straker, Hong Kong ( EDT =

12)

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3CAST-Causal Analysis using System Theory:

Implementation – How and Why?

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❑ During the initial stage of an CAST accident investigation, following

identification of the SYSTEM LEVEL HAZARDS, CONTROL STRUCTURE,

PROXIMTE, the CAST Analysis will:

❑ Grouping the focus of the questions allows for faster orientation of the

investigation

❑ Cost effective, resource allocation is simplified, and reports are

completed faster when it is practical to do so.

❑ Good for complex Investigation with significant Human/Machine Interface

areas

❑ CAST is prescriptive - embedded in the CAST ‘procedure’ is the idea of

Optimisation.

5CAST Analysis Integrated into the Annex 13

SARP’s

Observation

Under the supervision of Prof Leveson a group of experts recently reanalysed, using the

final published report as source data, the final accident reports of high profile major

accident’s.

The focus of the reports differed from the official versions as did the safety

recommendations. Focus, Emphasis, Prioritization and the Conclusions differed from the

Official State Final Report

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DOCUMENT RETRIEVAL INFORMATION

Report No.

AR-2007-053

Publication date

11 March 2008

No. of pages

106

ISBN

978-1-921165-97-9

Publication title

Analysis, Causality and Proof in Safety Investigations

Author(s)

Walker, Michael B., and Bills, Kym M.

Prepared by Reference No.

Australian Transport Safety Bureau Mar2008/Infrastructure 8060

PO Box 967, Civic Square ACT 2608 Australia

www.atsb.gov.au

Abstract

The quality of a safety investigation’s analysis activities plays a critical role in

determining whether the investigation is successful in enhancing safety. However,

safety investigations require analysis of complex sets of data and situations where

the available data can be vague, incomplete and misleading. Despite its importance,

complexity, and reliance on investigators’ judgements, analysis has been a neglected

area in terms of standards, guidance and training of investigators in most

organisations that conduct safety investigations.

To address this situation, the Australian Transport Safety Bureau (ATSB) developed

a comprehensive investigation analysis framework. The present report provides an

overview of the ATSB investigation analysis framework and concepts such as the

determination of contribution and standard of proof. The report concludes by

examining the nature of concerns that have been raised regarding the ATSB analysis

framework and the ATSB’s consideration of these concerns.

The ATSB believes that its investigation analysis framework is well suited to its role

as an independent, no-blame safety investigation body. It is hoped and expected that

ongoing development and provision of information about the framework can help

the safety investigation field as a whole consider some important issues and help

develop the best means of conducting safety investigations to enhance future safety.

- vii -

Understanding Accident Analysis

CAST is structured, it’s a prescriptive process that has the intent to capturethe complete accident causation to ensure understanding of the entire accident process and all systemic causal factors involved

This includes not only the verifiable known factual information but also the subjective human factors and empirical evidence.

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8Summary of Investigative Model Groups

The reason for reluctance to adopt System Safety investigation and the very

low uptake of implementation by States or Regions are varied. Some States

have imbedded IT systems and legacy software for example Bow-Tie, some

States view CAST as complex: Current States and Regions using Systemic

investigative methods is only 3%

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Safety ConstraintsHierarchical Control Structures

Process Models

In STAMP, accidents are conceived as resulting not from

component failures, but from inadequate control or

enforcement of safety-related constraints on the

development, design, and operation of the system. The most

basic concept in STAMP is not an event, but a constraint

STAMP – Basic Constructs

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OVERVIEW HCS

Aircraft PH-SOLAircraft G-LEAAAircraft G-LEAA

Controlled Process

(Physical Process)

Aircraft

(Cessna 510)

G-LEAA

Incident Report

2009073_G-

LEAA_ENG_.pdf

Dutch Safety

Board (DSB)

Serious Incident

Investigation

?

Local Regulator

?

NL.Gov

?

Aircraft

(Cessna 510)

G-LEAA

First Officer

(RH Seat)

Aircraft Captain

(LH Seat)

Flight

Plan

Delivery

Controller

KLM

Jet Center

?

?

International Civil

Aviation Organisation

(ICAO)

?

Doc 4444

Procedures for Air

Navigation Services-

Air Traffic Management

Standard Phraseology

?

?

?

?

Ground

Controller

Runway

Controller

Ground

RADAR

Aircraft

(Cessna 525)

PH-SOL

Aircrew

?

?

Stop Bar

Red

Lights?

?

Aircraft Captain

(LH Seat) X?

? ???

?

?

Trajectory / Path Trajectory / PathTrajectory / Path

?

?

Visual

Radio

Recorder

Transcript

Royal Netherlands

Meteorological

Institute

Report

Visual

Procedures for

Restricted

Visibility

?

Pilot / Airline

Local Regulator /

Licensor?

?

?

?

?

Airline /

Operator?

Airport / ATC

Management

?

?

?

?

CA MM CA MM CA MM

CA MM CA MMCA MMCA MM

Radio Equipment

-Reported

Radio Equipment Radio Equipment

-GO AROUND

-Permission to

Land RWY 22

-Approaching

RWY 22 to Land

?

xx

-Approaching GD

-Continue to RWY 22

-(20 sec Delay) Contact

Runway Controller

119.22 Mhz

CA MM

-Permission to Taxi

from K12 to GD

-Clearance

Flight to Luton

-Permission

Engine Start

Visual

-Remain Stationary

-Taxied onto RWY without permission

First Officer

(RH Seat)CA MM

CAST Control Structure Complexity

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The Process Model allows the Human Factors component and experience to be introduced.

A major improvement, as factoring in knowledge and experience into second guessing a motive for a crew action is subjective and can be problematic unless justified to a reasonable level of confidence

Crew Awareness to Control Smoke in the Cockpit

Data Determination – Proximate Events

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1. Factual All information relevant to an understanding of

the factual information, analysis and conclusions

is included under each appropriate heading;

2. AnalysisAnalyse, as appropriate, only the information

documented in 1. — Factual information and

which is relevant to the determination of

conclusions and causes and/or contributing

factors.

3. ConclusionsList the findings, causes and/or contributing

factors established in the investigation. The list of

causes and/or contributing factors should include

both the immediate and the deeper systemic

causes and/or contributing factors.

4. Safety RecommendationsAs appropriate, briefly state any

recommendations made for the purpose of

accident prevention and identify safety actions

already implemented

ICAO Annex 13 Frames of Reference

13CAST Integration into the ICAO Annex 13

Format

Typical Major Accident Areas of Investigation

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1. Factual All information relevant to an

understanding of the factual information,

analysis and conclusions is included under

each appropriate heading;

2. AnalysisAnalyse, as appropriate, only the

information documented in 1. — Factual

information and which is relevant to the

determination of conclusions and causes

and/or contributing factors.

3. ConclusionsList the findings, causes and/or contributing

factors established in the investigation. The

list of causes and/or contributing factors

should include both the immediate and the

deeper systemic causes and/or

contributing factors.

4. Safety RecommendationsAs appropriate, briefly state any

recommendations made for the purpose of

accident prevention and identify safety

actions already implemented

15CAST Analysis Integrated into the Annex 13

SARP’s

Observation

The initial benefit could be GA and commercial aircraft under 5700kg:

Justification:

Less depth of knowledge is required, less specialisation (Human Factors is normally HFACS),

more flexibility to implement an overall CAST process where subjectivity is less critical (Mental

Models and assumptions) and methods can be prescriptive with lower time frames for

completion.

Adopted as a standard working model it will simplify investigation, optimise the report writing

and reduce the investigation timelines for effective safety improvements across the board.

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