What criteria defines an aircraft accident?

The criteria that defines an aircraft accident focuses on significant events that result in serious injuries or fatalities, along with substantial damage to the aircraft. In this context, the correct answer highlights that an aircraft accident is defined by occurrences from the moment of boarding until disembarking, provided that there is serious injury involved. This includes not just events during flight but can encompass incidents occurring during the entire flight operation process.

Additionally, the emphasis on serious injuries provides clarity on the severity required to classify the event as an accident rather than a mere incident. This distinction is vital in aviation safety since it helps in analyzing and addressing the causes of such severe outcomes.

Understanding the broader definition of an aircraft accident helps stakeholders in aviation—like flight instructors, safety officials, and investigators—evaluate risks effectively and develop necessary safety measures. In contrast, options referencing lesser incidents or activities unrelated to the passenger experience during flight lack the severity and comprehensive scope required for classification as an accident.