To alert customs when entering or leaving the U.S., what must pilots file in the ADIZ?

Filing a flight plan is the correct requirement for pilots when entering or leaving the U.S. in the Air Defense Identification Zone (ADIZ). This is important because the flight plan not only provides authorities with details about the flight route, altitude, departure, and arrival times but also ensures that appropriate measures can be taken if there are any deviations from the planned route or if there are safety concerns.

The filing of a flight plan serves as a mechanism for communication with air traffic control and assists in the identification of aircraft in the congested airspace around the U.S. This enhances both security and safety for air travel.

In contrast, the other options may not fulfill the specific legal or procedural requirements in the context of the ADIZ. Security authorizations or access requests are not the primary means of communicating flight intentions or movements to customs. Standard flight notifications may be applicable for certain types of operations but do not replace the formal requirement of filing a flight plan. Thus, filing a flight plan is the critical step for compliance with U.S. customs protocols in the ADIZ.