During flight, if a fire burns insulation from a wire, what is the required action?

Immediate notification to the National Transportation Safety Board (NTSB) is essential in this situation because it represents a serious safety incident that could impact the safety of the flight and potentially involve significant regulatory consequences. Fires during flight can indicate severe issues with the aircraft that require immediate investigation to ensure the safety of future operations. The NTSB plays a critical role in investigating aviation accidents and incidents, so reporting such an event promptly allows for a thorough examination of the causes and contributes to overall aviation safety improvements.

The NTSB needs to be aware of incidents that could affect the safety of the flying public, as well as to gather data that might prevent future occurrences. The severity of a fire during flight means it's not simply a minor maintenance concern; it has implications for system reliability and passenger safety that must be addressed immediately.

Other options might suggest a lesser degree of urgency or importance regarding reporting procedures, which doesn't align with the critical nature of a fire incident involving aircraft wiring.