The focus of this analytical technique is justified by the observation that deviations from normal operations are often cited as a cause in many accidents and incidents. It is important to emphasise, however, that these changes are often made with the best intentions. For instance, new working practices may help to ensure that organisations satisfy regulatory requirements. Alternatively, new production processes can be introduced to improve organisational efficiency. Problems arise not from the intention behind such changes but from the difficulty of predicting the impact that even small changes can have upon the operation of complex, technological systems. Even apparently beneficial changes can have unintended consequences that, in the medium or long term, can help to produce incidents and accidents.
Key Stages in Change Analysis
In incident investigation, change analysis can be applied to identify the differences between what was expected to occur and what did occur during the event. The findings should be added into the development of ECF charts.
Key stages for Change Analysis:
- Define the problem
- Establish what should have happened
- Identify, locate and describe the change
- Specify what was and what was not affected
- Identify the distinctive features of change
Difficulties in Change Analysis
- It can be difficult to identify operating norms. Investigators should use blueprints, equipment description documents, drawings and schematics, operating and maintenance procedures, job/hazard analyses, performance indicators etc to determine the nominal operating conditions before any incident.
- Subtle differences often occur in the way different sites operate the same process. Even within the same site, there will be differences in the performance of different shifts and of individuals within those shifts.
- Most applications continue to operate in spite of documented failures in non-critical components, and wait for major repairs before halting a process. Further problems stem from the effects of compound changes; procedures and actual practice evolve slowly over time so that official documents may reflect a situation that was true several years previously. Under such circumstances, previous distinctions between normal and abnormal practices can become blurred.
- Individuals may be unable to recall what happened in the aftermath of an adverse event. There is also a temptation for operators to describe violations as abnormal occurrences even though they may have formed part of everyday working practices. Organisation, managerial and social pressures influence their participation in a primary and secondary investigation. Inconsistencies, omissions and ambiguity are a continual problem when investigators must form coherent accounts from eye-witness statements.
Design of Table for "Change Analysis"
| Present Condition | Prior/Ideal Condition | Effects of Change |
|---|---|---|
| Mars Surveyor 98 faces pressures to push boundaries of technology and cost | Faster, better, cheaper strategy required sufficient investment to validate high-risk technologies before launch |
• Greater development effort
• Use off-the-shelf hardware and inherited designs as much as possible
• Use analysis and modelling as cheaper alternatives to system test and validation
• Limit changes to those required to correct known problems; resist changes that do not manifestly contribute to mission success
|
The "present condition" usually can be directly applied to the ECF chart as a condition. But it often necessitates the creation of a new event which may even need to be added to the primary event chain to explain change mechanisms. Change analysis provides a good means of identifying the wider contextual issues and the impact of managerial and organisational strategy that can often be overlooked by more event-based approaches.
Practice Change Analysis
- Patient fall from wheelchair
- Apply your findings to your ECF diagram(s) for the incident