The extent of an AAIU investigation is determined by the Chief Inspector, taking into account the lessons that the investigation may hold for the prevention of future accidents. The type of Report published and the associated timelines are generally related to the severity and scale of the occurrence and the extent in which the occurrence is being investigated.
For a high profile occurrence that involves fatalities, significant serious injuries or extensive damage to the aircraft, a Preliminary Report may be published approximately 30 days after the event occurred. The Preliminary Report will only identify factual information known at that time and will not contain any analysis of the factual information, conclusions, or probable cause.
High profile occurrences will follow the full ICAO Annex 13 Formal Report format covering all aspects of an investigation. Such Formal Reports are complex and because each investigation is methodical and scientifically reviewed, determining the exact length of the investigation is difficult. However, where the investigation extends beyond a year, an Interim Statement will be released at least at each anniversary of the occurrence.
For occurrences that do not include fatalities a Synoptic Report will be published. In general, the investigation process is somewhat shorter, as only specific and relevant aspects of the full ICAO Annex 13 Report format need to be covered.
For relatively minor events a Factual Report will be published outlining the basic facts only. This Factual Report will not provide analysis, but may contain brief AAIU comment.