10:15 a.m. September 11, 2001: NORAD Operations Center in Colorado Closes Its Blast Doors

The massive doors leading to NORAD’s operations center in Cheyenne Mountain, Colorado, designed to protect the center from a nuclear blast, are closed for the first time ever in a real-world, non-exercise event, though the reason for this is unclear. [Toronto Star, 12/9/2001; Aviation Week and Space Technology, 6/3/2002; BBC, 9/1/2002; North American Aerospace Defense Command, 9/9/2011] The two steel blast doors, one third of a mile inside the mountain, guard the heart of NORAD’s Cheyenne Mountain Operations Center (CMOC) and are intended to seal the complex to protect it from a nuclear strike. The doors are three feet thick, more than 10 feet high, and each weigh 25 tons. During an attack, they can swing shut in 30 to 40 seconds. [Airman, 1/1996; Nation, 5/5/2008; Colorado Springs Gazette, 5/10/2008]
Doors Are Shut for the First Time, except for Exercises – Air Force officer William Astore will later recall that when he worked inside Cheyenne Mountain between 1985 and 1988, the blast doors were kept open, “except, of course, during ‘exercises,’ when the mountain ‘buttoned up’ its self-contained world.” [Nation, 5/5/2008] Now is the first time since the CMOC opened in 1966 that the blast doors have been shut because of a real-world, non-exercise event. Lieutenant Colonel Steven Armstrong, NORAD’s chief of plans and forces, who is in the CMOC on this day, will later comment, “The fact that we closed the blast doors… was a significant event.” [Toronto Star, 12/9/2001; Colorado Springs Gazette, 6/14/2004; North American Aerospace Defense Command, 9/9/2011]
Accounts Conflict over Why the Doors Are Closed – The reason the blast doors are shut is unclear. According to the Toronto Star, they are closed because “no one yet knew who was behind the attack—or what else might be en route.” [Toronto Star, 12/9/2001] But Aviation Week and Space Technology magazine will report that “NORAD commanders ordered [the] massive steel doors be closed” after “someone—possibly President Bush—ordered the military to a Force Protection Condition Delta wartime posture” (see (Between 10:10 a.m. and 10:35 a.m.) September 11, 2001). [Aviation Week and Space Technology, 6/3/2002] Other reports will say the doors are shut due to a report the CMOC received about an aircraft that is incorrectly suspected of being hijacked and targeting Cheyenne Mountain (see (10:10 a.m.) September 11, 2001). [BBC, 9/1/2002; Grant, 2004, pp. 26; Colorado Springs Gazette, 6/14/2004; Washington Post, 7/29/2006] A NORAD representative on the Pentagon’s air threat conference call will report over the conference call that the blast doors are in fact shut in response to information received at the CMOC about a number of suspicious trucks that are supposedly heading toward the CMOC (see (Shortly After 1:05 p.m.) September 11, 2001). [US Department of Defense, 9/11/2001 ]
Doors Are Re-Opened Four Hours Later – The blast doors will be re-opened four hours after they are shut, “when officials learned the threat was bogus,” according to the Colorado Springs Gazette. [Colorado Springs Gazette, 6/14/2004]