Policy on Occurrence Classification
Effective May 1, 2018
1.1 Each year, between 3000 and 4000 transportation occurrences are reported to the Transportation Safety Board of Canada (TSB) in accordance with the mandatory reporting requirements in the Transportation Safety Board Regulations (TSB Regulations). Numerous other events/occurrences are also reported to the TSB on a voluntary basis. Practical considerations dictate that only a small proportion of these occurrences can be fully investigated.
1.2 Section 7(1) of the Canadian Transportation Accident Investigation and Safety Board Act (the CTAISB Act) states that the object of the Board is to advance transportation safety by conducting independent investigations into selected transportation occurrences in order to make findings as to their causes and contributing factors. The TSB is therefore not obligated to investigate all reported occurrences.
1.3 Section 8(1)(b) of the CTAISB Act provides the Board with the authority to establish policies respecting the classes of transportation occurrences to be investigated.
2.1 "Occurrence" means a transportation event as defined in the CTAISB Act.
2.2 "Reportable occurrence" means an occurrence as defined in the TSB Regulations.
2.3 "Investigation" means all activities associated with the collection of data/ information pertaining to an occurrence (except the receipt and capture of the initial occurrence notification information), the analysis of such information (including laboratory projects and testing), the drafting, review and approval of the report, the publication of the report, as well as all communications activities intended to share information with external stakeholders.
2.4 "Report" means an official publication presenting the results of an investigation in a format prescribed by the Board and made available to the public.
2.5 "Occurrence summary" means a short summary describing the basic facts of an occurrence.
2.6 "Incident" is defined in Appendix A for each mode of transportation.
2.7 "Accident" is defined in Appendix A for each mode of transportation.
3. Policy objective
3.1 The purpose of this policy is to establish a classification structure to facilitate tracking, investigating and reporting of transportation occurrences in accordance with Section 8(1)(b) of the CTAISB Act.
3.2 This policy also sets specific criteria for investigations within each class of occurrence to
4. Policy requirements
4.1 Mandatory data, as defined in the TSB Regulations, shall be collected for all reportable occurrences and recorded in the mode's transportation occurrence database.
4.2 Each occurrence reported to the TSB shall first be classified as an "accident" or an "incident" in order to facilitate statistical tracking, analysis and reporting. This classification shall be done in accordance with the definitions included in Appendix A.
4.3 Occurrences shall then be classified according to their relative importance, complexity, and potential for yielding safety lessons. This classification shall be done in accordance with the criteria and definitions included in Appendix B.
4.4 There are five classes of occurrences:
4.5 This classification is used to determine the TSB's level of effort and investment, the investigation process, the type of report or product, and the target timeline, as shown in Appendix C.
4.6 Occurrences outside Canada that the TSB investigates will be classified in the same way as occurrences in Canada.
4.7 To the extent practicable, an individual occurrence will be classified within 72 hours of receiving the initial occurrence notification.
4.8 If a measurable level of effort is made (such as deployment to the occurrence site or a laboratory project), the occurrence will generally be classified as a class 4 or above.
4.9 The classification of an occurrence can be modified (upgraded or downgraded) whenever new supporting information becomes available to justify such a change. However, once an occurrence has been classified as a class 2, 3 or 4, it cannot be downgraded to a class 5.
4.10 An investigation in progress may be re-scoped if no further safety lessons emerge.
4.11 All classification decisions and the rationale for them must be documented in the investigation records.
5.1 This policy is issued under the authority of the Board in accordance with sections 8(1)(b) and 8(1)(c) of the CTAISB Act. It was approved by the Board on April 25, 2018, after consultation with the Executive Committee
5.2 This policy will be reviewed and may be updated in response to changes in government priorities or TSB strategic direction, but at least once every 5 years.
6. Role and responsibilities
The Chair is responsible for initiating the periodic review and update of this policy by the Board.
6.2 Chief operating officer
The chief operating officer is responsible for overall implementation, monitoring and oversight of this policy, as well as for seeking interpretation and guidance from the Board from time to time.
6.3 Directors of investigations and director, Operational Services
The directors of investigations (DOIs) and the director, Operational Services are responsible for communicating and implementing this policy within their respective branches. This includes ensuring that all manuals, directives, procedures, standards, and guidelines are fully compliant with this policy.
The DOIs are accountable for classification decisions.
Where appropriate, the DOIs are accountable for re-scoping further investigation work as stated in section 4.10.
6.4 Director, Communications
The director, Communications is responsible for posting this policy on the TSB website and for responding to information requests from the public.
7.1 The following acts and regulations apply:
7.2 This policy was drafted with consideration given to TSB obligations and commitments to the following international agreements and conventions:
8.1 Questions about this policy may be addressed to:
Appendix A – Definitions of accident and incident for each mode
All reportable occurrences must be identified as an accident or an incident in the transportation occurrence modal database using the following definitions, which are based on the Transportation Safety Board Regulations SOR/2014-37.
A1 – Aviation accident
An aviation accident is an occurrence resulting directly from the operation of an aircraft in which
A2 – Aviation incident
An aviation incident is an occurrence resulting directly from the operation of an aircraft having a maximum certificated take-off weight greater than 2250 kg or of an aircraft being operated under an air operator certificate issued under Part VII of the Canadian Aviation Regulations in which,
A3 – Marine accident
A marine accident is an occurrence resulting directly from the operation of a ship other than a pleasure craft in which
A4 – Marine incident
A marine incident is an occurrence resulting directly from the operation of a ship other than a pleasure craft in which
A5 – Pipeline accident
A pipeline accident is an occurrence resulting directly from the operation of a pipeline in which
A6 – Pipeline incident
A pipeline incident means an occurrence resulting directly from the operation of a pipeline in which
A7 – Railway accident
A railway accident means an occurrence resulting directly from the operation of rolling stock in which
A8 – Railway incident
A railway incident means an occurrence resulting directly from the operation of rolling stock in which
Appendix B – Classifying occurrences
In some cases, a deployment may be required to evaluate physical evidence, interview personnel or witnesses, review documentation, etc., before finalizing a classification decision.
B1 – Factors to consider in deciding to deploy
Directors of investigations and their delegates should consider the following factors in their decision to deploy:
B2 – Key factors to consider when classifying an occurrence
The following factors must be considered when classifying an occurrence:
Most of these factors are self-explanatory. A detailed description of some factors is provided below.
Obligations and commitments
Canada is signatory to several international agreements pertaining to the conduct of investigations. The TSB is also party to several agreements for the provision of assistance to particular nations or provinces. The TSB must ensure such obligations and commitments are met.
Canadian interests in foreign occurrences
Sometimes occurrences outside Canada involve Canadian-manufactured transportation products, Canadian carriers, Canadian crews, or large numbers of Canadian citizens travelling with foreign carriers. The TSB must ensure that foreign occurrences in which Canadian products, services, or citizens are involved are appropriately investigated and that Canadian interests are adequately represented in these investigations.
Past TSB experience
In its investigations, the TSB has identified safety issues that have not been resolved over time, has published safety concerns, and noted emerging issues of interest. The TSB Watchlist, particularly, identifies the key safety issues posing the greatest risks to the transportation system.
New occurrences that are considered likely to involve risks similar to those found in previous investigations should be investigated in order to collect information that could strengthen the case for safety action.
Similarly, occurrences with safety issues that are related to Board concerns or that are among the emerging issues of interest to the TSB should be investigated in order to collect information that could contribute to the analysis of these issues and lead to new findings and recommendations.
The following questions are used in the occurrence classification to assess the probability of adverse consequences arising in similar occurrences in the future:
In assessing the severity of the consequences of the occurrence, consideration is given to the following:
Sometimes, even if there is little doubt that an unsafe condition with unacceptable risk exists, the potential for further practical safety action is limited. Consequently, an assessment will be made not only of the risks but of the potential for discovering new and meaningful safety lessons and for safety action being taken in a reasonable time in response.
To determine the value of the safety lessons that an investigation is likely to yield, the following questions should be considered:
B3 – Classes of occurrences
Class 1 occurrence
A class 1 occurrence is a series of occurrences with common characteristics that have formed a pattern over a period of time. This pattern is made of one or more significant safety risks previously identified by the TSB or organizations in other jurisdictions in the course of their investigations, or of an issue of interest that has emerged from statistical analysis.
Class 2 occurrence
A class 2 occurrence has significant consequences that attract a high level of public interest across Canada or internationally. A large number of people are affected, some of whom may be fatally or seriously injured. There may be a large release of dangerous goods. There is significant damage to property and/or the environment. There is a high public expectation that the TSB will investigate. There is a high likelihood of identifying new safety lessons and of advancing transportation safety by reducing risks to persons, property, or the environment. A complex and exhaustive investigation is required.
Class 3 occurrence
A class 3 occurrence may have significant consequences that attract a high level of public interest. It may involve multiple fatalities and/or serious injuries. There may be a medium-sized release of dangerous goods. There is moderate to significant damage to property and/or the environment. There are public expectations that the TSB will investigate. It is quite likely that new safety lessons will be identified and that transportation safety will be advanced by reducing risks to persons, property, or the environment. A detailed investigation is required.
Class 4 occurrence
A class 4 occurrence may have some important consequences. It may involve fatalities or serious injuries. There may be a small release of dangerous goods. There is moderate to minor damage to property and/or the environment. The occurrence attracts public interest within the immediate region or province/territory. The likelihood of identifying new safety lessons and of advancing transportation safety by reducing risks to persons, property, or the environment is low.
Class 5 occurrence
A class 5 occurrence has little likelihood of identifying new safety lessons that will advance transportation safety. The occurrence may involve fatalities and/or serious injuries. There is little or no release of dangerous goods. There is minimal damage to property or the environment. The occurrence attracts limited public interest outside of the immediate area. The investigation is limited to data gathering and the data are recorded for statistical reporting and future analysis.
An occurrence that has been reported voluntarily and is not subject to the mandatory reporting requirements in the TSB Regulations may nonetheless be classified as a class 5 occurrence if it is of interest to the TSB.
Appendix C – Investigation processes and products
Each class of occurrence follows a different process and results in a different product, as summarized in the table below. A short description of these processes and products follows the table.
|Class||Investigation type||Level of effort||Level of Investment||Investigation process||Type of report||Target timeline|
|1||Safety issue||Very high||Very high||Complex||Detailed; long||730 days|
|2||Complex||Very high||Very high||Complex||Detailed; long||600 days|
|3||Detailed||High||High||Medium complexity||Medium length: up to 30 pages or 10 000 words in English, plus appendices||450 days|
|4||Limited scope||Medium||Medium||Simple||Short, without findings or recommendations: up to 6 pages or 2000 words in English||200 days|
|5||Data gathering||Low||Low||Data gathering||Occurrence summary *||60 days|
* The publication of class 5 occurrence summaries will be implemented at a later date.
Safety issue investigation (of a class 1 occurrence)
A safety issue investigation is a detailed study of a series of occurrences with common characteristics that have formed a pattern over a period of time. A safety issue investigation is conducted by a large team led by an investigator-in-charge. This type of investigation generally involves participants from multiple branches. A detailed work plan and methodology is developed and submitted to the Board for approval prior to the start of the investigation. Significant effort is placed on the collection, review and analysis of data from various internal and external sources. The report is lengthy and detailed. Investigation updates or interim reports may be released during the investigation. This type of investigation may include recommendations. The investigation is generally completed within 730 days.
Complex investigation (of a class 2 occurrence)
A complex investigation for a class 2 (i.e., major) occurrence is conducted by a large team and led by an investigator-in-charge. It involves multiple branches as well as groups with chairs and/or leads. It is conducted in accordance with the major occurrence procedures described in the TSB Manual of Investigation. It requires a very high level of effort and dedicated resources. Special funding may be required from the Treasury Board.
A class 3 occurrence that involves several safety issues requiring in-depth analysis and a complex investigation should be reclassified as a class 2. The investigation is conducted by a small team and led by an investigator-in-charge. It involves participants from multiple branches, with assistance from functional specialists (e.g., human factors, engineering). It is conducted in accordance with the standard investigation methodology described in the TSB Manual of Investigation, but it involves a higher level of effort and is more complex than a detailed investigation.
The investigation report is detailed and presents several safety issues. Investigation updates may be released during the investigation. There may also be group reports and numerous laboratory projects. This type of investigation frequently results in recommendations. The investigation is generally completed within 600 days.
Detailed investigation (of a class 3 occurrence)
A detailed investigation is conducted by a small team and led by an investigator-in-charge. It involves participants from multiple branches, with assistance from functional specialists (e.g., human factors, engineering). It is conducted in accordance with the standard investigation methodology described in the TSB Manual of Investigation. It requires a high level of effort and is of medium complexity.
The report is of medium length and presents a small number of safety issues; it has up to 30 pages or approximately 10 000 words in English, plus appendices. Investigation updates may be released during the investigation. This type of investigation may result in recommendations. The investigation is generally completed within 450 days.
Limited-scope investigation (of a class 4 occurrence)
A limited-scope investigation is conducted by an investigator-in-charge with some support from other investigators and/or functional specialists. It requires a medium level of effort and is of low complexity.
The report is short (up to 6 pages or approximately 2000 words in English) and is mostly factual; it may contain limited analysis, but it does not include findings or recommendations. This type of investigation is generally completed within 200 days.
Data-gathering investigation (of a class 5 occurrence)
The investigation of a class 5 occurrence is limited to data collection. There is generally no deployment to the occurrence site and no laboratory or human factors work is done for it. The data collected is entered into the modal database and an occurrence summary is published. It requires a low level of effort and is of low complexity. The investigation is generally completed within 60 days.
- Footnote 1
HVP means high vapour pressure as defined in CSA Z662. CSA Z662 means Canadian Standards Association Standard Z662 entitled Oil and Gas Pipeline Systems, as amended from time to time.
- Footnote 2
LVP means low vapour pressure as defined in CSA Z662.
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