What does the TSB classify missing aircraft as?

The Transportation Safety Board (TSB) classifies missing aircraft as a reportable aviation accident because the circumstances typically indicate a significant risk to safety. When an aircraft is reported missing, it suggests that there may have been an incident involving the aircraft that has serious implications for passengers, crew, and potentially the public. This classification is crucial as it triggers an investigation by the TSB to determine the causes and contributing factors of the incident, which is essential for improving aviation safety. The process of investigation and reporting is designed to prevent future occurrences, which emphasizes the severity and importance of such situations.