Final answer:
The TSB is responsible for investigating transportation incidents to improve safety. Their goal is to find root causes and prevent future incidents, without assigning liability.
Step-by-step explanation:
When a reportable incident or accident occurs, the Transportation Safety Board (TSB) shall initiate an investigation to understand the root causes and to prevent future occurrences. The TSB's mandate involves enhancing transportation safety in aviation, marine, pipeline, and rail modes by conducting independent investigations, issuing safety recommendations, and publishing reports on their findings. Their primary focus is to improve safety and not to assign fault or determine civil or criminal liability.