The Investigative Process

While the exact scope and extent of any specific investigation depends on the nature of the accident being investigated, every NTSB investigation goes through the same general process, which involves:

1. the initial notification and decision to investigate;
2. on-site fact gathering;
3. analysis of facts and determination of probable cause;
4. acceptance of a final report; and
5. advocating for the acceptance of safety recommendations arising from the investigation.

This process is not strictly linear, and phases overlap. For example, investigators may be waiting for log books while they are analyzing weather information, or their analysis of engine performance data may prompt them to request additional information from the manufacturer.

The timing between the beginning of an investigation and a probable cause determination and report varies based on the complexity of the investigation and the workload of the agency’s investigators. In general, the NTSB tries to complete an investigation within 12 to 24 months, but these and other factors can greatly affect that timing.