* * * * * By the middle of spring, 1973, World Associates had purchased a new Cessna 172, modified it as a Sky Sentinel , and was demonstrating it for various law enforcement agencies around the country – prompting the Albuquerque Police Department to place an order for one. Albuquerque PD’s Special Purpose Vehicles. About this same time Hugh C. McDonald’s brother-in-law, who had retired from the U.S. Border Patrol, arranged for the Sky Sentinel to fly a two-week test for the USBP in the San Diego area. I got tapped to perform this test, and moved our demonstrator-aircraft down to Brown Field Municipal Airport – five miles inland from the coast, 13 miles southeast of San Diego, and 1.5 miles north of the US/Mexican ...