If an aviation accident results in substantial damage, when should the nearest NTSB field office be notified?

When an aviation accident results in substantial damage, the nearest National Transportation Safety Board (NTSB) field office must be notified immediately. This requirement is in place to ensure a prompt investigation into the accident, which is crucial for determining the causes and any contributing factors. Timely reporting allows the NTSB to gather essential evidence and witness statements while they are still available, and it facilitates a thorough investigation that can enhance aviation safety and prevent future incidents.

The 24 and 48-hour timelines presented in other options do not align with the need for instant reporting when significant aircraft damage occurs. Waiting for recovery of the aircraft could lead to loss of critical data and delay the investigation process, undermining the goals of safety and regulatory compliance that the NTSB aims to achieve.