What is the function of an ADIZ?

The function of an Air Defense Identification Zone (ADIZ) is to require pilots operating in specific airspace to file Defense Visual Flight Rules (DVFR) flight plans, particularly for customs notification purposes. This requirement is crucial for national security as it helps authorities track and identify aircraft entering or operating within the zones that are typically near the borders of a nation or in areas with heightened security concerns. By mandating DVFR flight plans, the government can effectively monitor and manage air traffic in and out of these sensitive areas, ensuring that all aircraft are accounted for and appropriately cleared.

In contrast, other choices provided do not accurately represent the primary purpose of an ADIZ. For example, while temporary pilot training zones and controlling airspace during major events are relevant considerations in aviation, they do not pertain specifically to the function of an ADIZ. Monitoring restricted military activities can be a part of airspace management but is also not the direct purpose of ADIZ regulations. Therefore, the requirement for DVFR flight plans underscores the ADIZ's role in maintaining air security and compliance with legal protocols.