San Antonio Express-News Senior Reporter Sig Christenson discusses details on the Air Force's claim that a team of researchers has cracked the mystery of why dozens of pilots, some of them in San Antonio, have suffered midair blackouts or other physiological episodes this year while flying the T-6A Texan II, the service’s primary trainer. Find more of Sig Christenson's coverage of military issues at https://www.expressnews.com/author/sig-christenson/.