Final answer:
Serious injuries in aircraft accidents/incidents are classified by the NTSB if an individual is hospitalized for more than 48 hours. These injuries can result in permanent brain damage and cause symptoms such as loss of consciousness and cognitive impairments.
Step-by-step explanation:
According to the National Transportation Safety Board (NTSB), an injury is classified as serious if the person is hospitalized for more than 48 hours. When an individual sustains a serious brain injury during an aircraft accident/incident, it typically results in permanent brain damage. Symptoms of severe brain injuries can include loss of consciousness, profound confusion, and difficulty with speech and body movements.