ATSB investigation reports

The ATSB will release a final report at the conclusion of an investigation, detailing contributing factors and any identified safety issues. However, at any time during the course of an investigation, should we uncover safety critical information we will immediately share that with relevant parties so they can take appropriate safety action.

Depending on the complexity of the occurrence and the scope of the investigation, the ATSB may also produce preliminary and interim reports.

Preliminary reports detail factual information determined in an investigation’s initial evidence collection phase, and are typically released 6-8 weeks after the initial occurrence.

Interim reports detail more extensive factual information and outline areas of ongoing investigation, but do not contain analysis or findings.

During the course of an investigation, the ATSB may also provide brief factual updates on investigation progress on our website.

Either in conjunction with a report release or at any time during an investigation, the ATSB may also issue a safety advisory notice to relevant organisations and industry sectors to highlight a safety issue or issues determined during the course of that investigation and recommending that they take safety action where appropriate.

Final report structure

ATSB occurrence investigation final reports are organised with regard to international standards or instruments, as applicable, and with ATSB procedures and guidelines. Reports normally contain the following sections:

  • Executive summary—a one-page summary of the transport safety occurrence, the findings and any safety action taken as a result, as well as any broader safety messages.   
  • The occurrence—a description of the sequence of events related to the occurrence and, if relevant, the consequences in terms of injuries and damage. 
  • Context—of evidence collected as part of the investigation that is necessary to help the reader understand the occurrence and safety analyses, or the broader safety issues for research purposes. 
  • Safety analysis—a demonstration of how the evidence justifies the investigation findings 
  • Findings—a list of contributing factors and other safety factors identified during the safety analysis. 
  • Safety issues and actions—a summary of safety issues that were identified during the investigation and details of what safety action has been taken, or is planned to be taken by relevant parties to address those issues. 
  • Appendices—additional information that supports the report, for example, specialist reports on materials failure or flight data analysis.

Report terminology

Safety factor: an event or condition that increases safety risk. In other words, it is something that, if it occurred in the future, would increase the likelihood of an occurrence, and/or the severity of the adverse consequences associated with an occurrence. Safety factors include the occurrence events (e.g. engine failure, signal passed at danger, grounding), individual actions (e.g. errors and violations), local conditions, current risk controls and organisational influences.

Contributing factor: a safety factor that, had it not occurred or existed at the time of an occurrence:
a) the occurrence would probably not have occurred; or
b) the adverse consequences associated with the occurrence would probably not have occurred or have been as serious, or
c) another contributing safety factor would probably not have occurred or existed.

Other factors that increase risk: a safety factor identified during an occurrence investigation which did not meet the definition of contributing safety factor but was still considered to be important to communicate in an investigation report in the interests of improved transport safety.

Other finding: any finding, other than that associated with safety factors, considered important to include in an investigation report. Such findings may resolve ambiguity or controversy, describe possible scenarios or safety factors when firm safety factor findings were not able to be made, or note events or conditions which 'saved the day' or played an important role in reducing the risk associated with an occurrence.

Safety issue: a safety factor that:
a) can reasonably be regarded as having the potential to adversely affect the safety of future operations, and
b) is a characteristic of an organisation or a system, rather than a characteristic of a specific individual, or characteristic of an operational environment at a specific point in time.

Safety action: the steps taken or proposed to be taken by a person, organisation or agency in response to a safety issue.

Safety recommendation: a formal safety recommendation made either during or at the end of an investigation, where the ATSB remains concerned that a safety issue has yet to be adequately addressed by the relevant organisation.

Probability expressions

The list below presents the verbal probability expressions used by the ATSB in our investigation reports to describe the degree of likelihood or chance that something was true, occurred, influenced something else or was a contributing safety factor. 

  • Almost certain ˃ 99% probability of occurrence
  • Very likely ˃ 90% probability
  • Likely, probably ˃ 66% probability
  • As likely as not - 33% to 66% probability
  • Unlikely ˂ 33% probability
  • Very unlikely ˂ 10% probability
  • Exceptionally unlikely ˂ 1% probability