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Accident investigation overview

An investigation team gathers the evidence for the Transport Accident Investigation Commission’s inquiry into an event.

The Commission is usually notified of event which it may decide to investigate by a transport sector regulator (Civil Aviation Authority, Maritime New Zealand, or NZ Transport Agency) or, sometimes, by an equivalent investigation body overseas, or by the vehicle operator.

An equivalent overseas organisation may ask the Commission to participate in the investigation of an event involving a New Zealand operated or manufactured vehicle, or in which a significant number of New Zealanders are involved.

The investigation team is led by an “investigator in charge” who is joined by colleagues and external expertise when required to gather and analyse the evidence before drafting up a report for consideration by the Commission, who will also be briefed on progress throughout. 

The “investigator in charge” will keep organisations and individuals closely connected with an accident, including the families of fatalities, up to date with general progress throughout.

Emergency services manage the initial reaction to an accident under protocols for events requiring multi-agency response. They then move to support the Commission’s control of the site which is assumed as soon as an inquiry is opened.

In the case of a major event, the investigation team is likely to be split into groups responsible for different aspects of the inquiry such as witnesses, wreckage, maintenance, weather, crew, and so on, as appropriate to the mode and event.

The Commission and its investigators have significant powers relating to entry of premises and to the gathering and control of evidence.

Strong legal protections exist to recognise the public interest in finding out what happened in a transport accident or incident in order to improve safety, and to make it easier for people and organisations to contribute freely and frankly to a Commission inquiry.

The Commission is part of the transport sector but completely independent of other public sector organisations and the Government in the conduct of its inquiries.  Any investigation by other authorities into an event for compliance with transport regulations, occupational safety and health issues, or possible criminal activity is completely separate. The only evidence that may be shared by TAIC with other inquiries is evidence that cannot be duplicated, such as physical evidence. However, interpretation of that evidence is not shared.

The evidence the Commission gathers (including witness interviews) and inquiry documents (including draft reports) are protected from general disclosure except for the purposes of the investigation (including the final published report) or as the result of a High Court order in rare circumstances. The Commission’s reports cannot be used in regulatory, criminal or civil proceedings, except by the Coroner at an inquest.

The Commission’s legal framework and working practices are designed to be consistent with international obligations and standards for safety–focused investigation of significant transport accidents or incidents set out in Annex 13 to the Convention on International Civil Aviation (ICAO) and International Maritime Organisation (IMO) Code for Casualty Investigation.


An inquiry will usually lead to the publication of a report by the Commission which: sets out the facts of an event, analyses them, lists the contributing factors, identifies the safety lessons, notes safety actions taken since, and makes recommendations that might help to reduce the chances of a similar event happening again.

Every inquiry has the potential to be systemic and wide-ranging - looking beyond the immediate people, vehicle and environment of the event to consider the likes of human factors, organisational, cultural and other issues within the training, regulatory, traffic control, vehicle design and maintenance, operator, training, industry and other systems or organisations involved.

Where the actions or inactions of an individual or organisation may appear to have been closely connected with events then they will have the opportunity to comment on a protected draft report before the Commission finalises its inquiry.

On rare occasions - for reasons such as the gravity, complexity or contentious nature of an inquiry - the Commission may hold private or public hearings of evidence or submissions on process or its protected draft report.

All aspects of an investigation, including analysis and draft reports are subject to internal peer review before being submitted to the Commission. The Commissioners are often separately advised on the investigation and draft reports by an independent expert “Assessor”.

An inquiry might take a year or more from the event to publication of the final report, although the Commission may issue urgent safety recommendations or a preliminary report before then if required.

Introduction to TAIC has more information about the Commission's mandate, structure and operations.

[April 2010]