Which of the following is not a security measure developed by the FAA and NAAA?

The correct answer indicates that locking the hopper gate in the closed position is not specifically listed as a security measure developed by the FAA and the NAAA. The primary goal of security measures in aviation, particularly for aerial applications, is to protect both the aircraft and sensitive agricultural products from theft and unauthorized access.

The other options reflect common security practices in aviation. Using anti-theft devices and lockable control surface devices helps to prevent tampering or theft of aircraft components. Escorting visitors at all times ensures that access to sensitive areas is controlled, thereby enhancing security around aircraft and equipment. The use of FAA-approved hidden cutoff switches is another security measure aimed at preventing unauthorized operation of the aircraft, ensuring that only authorized personnel can access critical functions of the aircraft.

By understanding these measures, individuals involved in aerial application can better appreciate the importance of maintaining security around their operations and the specific recommendations set forth by authoritative bodies like the FAA and NAAA.