ROCKVILLE, Md. — The passage of almost 60 years has done nothing to dim former Navy fighter pilot Everett Alvarez Jr.’s memories of the night that he was shot down in the South China Sea and began what would be the second-longest period of captivity for an American service member in the Vietnam War. At 85 years old, Alvarez still vividly remembers his Douglas A4 Skyhawk filling with smoke and coming apart as he had just a few seconds to make a series of life-or-death choices. “I was really low. I knew I had to get out right there,” he...