Just after 11:30 pm on Oct. 1, Air Force Maj. Charles Chesnut awoke to an alarming cryptic alert from Air Combat Command’s AtHoc Emergency Mass Notification System: Avoid downtown Las Vegas. An hour and a half earlier, at 10:08 pm 64-year-old Stephen Paddock had opened fire from his room on the 32nd floor of the Mandalay Bay casino and resort on a crowd of 22,000 revelers gathered below for a music festival.