The North American Aerospace Defense Command (NORAD), the military organization responsible for monitoring and defending US airspace, gradually reduces the number of aircraft it has on “alert”—armed and ready for immediate takeoff—in response to the changing nature of the threats it has to defend against, so that there will be just 14 fighter jets on alert across the continental United States when the 9/11 attacks take place. [Jones, 2011, pp. 7-8]
NORAD Has 1,200 Interceptor Aircraft in 1960 – NORAD is a bi-national organization, established by the US and Canada in 1958 to counter the threat posed by the Soviet Union. [9/11 Commission, 7/24/2004, pp. 16] It is initially responsible for intercepting any Soviet long-range bombers that might attack the Northern Hemisphere. By 1960, it has about 1,200 interceptor aircraft dedicated to this task. But during the 1960s, the Soviets become less reliant on manned bombers, and shift instead to ballistic missiles. In response to this changed threat and also budget constraints, the number of NORAD interceptor aircraft goes down to about 300 by the mid-1970s.
NORAD’s Mission Changes after Cold War Ends – With the collapse of the Soviet Union and the dissolution of the Warsaw Pact in 1991, the threats NORAD has to counter change significantly. During the early 1990s, NORAD’s mission consequently changes from one of air defense to one of maintaining “air sovereignty,” which NORAD defines as “providing surveillance and control of the territorial airspace.” The new mission includes intercepting suspicious aircraft, tracking hijacked aircraft, assisting aircraft in distress, and counterdrug operations. [General Accounting Office, 5/3/1994, pp. 14-15; 9/11 Commission, 2/3/2004 
; Jones, 2011, pp. 7] As this change takes place, the number of aircraft defending American airspace is reduced. In 1987, there are 52 fighters on alert in the continental United States. [Filson, 1999, pp. 112-113] But by December 1999, there are just 14 alert fighters remaining around the continental US. [Airman, 12/1999]
Number of Alert Sites Goes Down Prior to 9/11 – The number of NORAD “alert sites”—bases where the alert aircraft are located—is also reduced in the decades prior to 9/11. During the Cold War, there are 26 of these sites. [9/11 Commission, 6/17/2004; 9/11 Commission, 7/24/2004, pp. 16] By 1991, there are 19 of them, according to Major General Larry Arnold, the commander of NORAD’s Continental US Region from 1997 to 2002. [Filson, 2003, pp. v] By 1994, according to a report by the General Accounting Office, there are 14 alert sites around the US. [General Accounting Office, 5/3/1994, pp. 1] And by 1996, only 10 alert sites remain. [Utecht, 4/7/1996, pp. 9-10]
Military Officials Call for Eliminating Alert Sites – In the 1990s, some officials at the Pentagon argue for the alert sites to be eliminated entirely. [9/11 Commission, 7/24/2004, pp. 16-17] The Department of Defense’s 1997 Report of the Quadrennial Defense Review indicates that the number of alert sites around the continental US could be reduced to just four, but the idea is successfully blocked by NORAD (see May 19, 1997). [Filson, 2003, pp. iv-v, 34-36; 9/11 Commission, 2/3/2004 ] However, three alert sites are subsequently removed from the air sovereignty mission. These are in Atlantic City, New Jersey; Burlington, Vermont; and Great Falls, Montana. [American Defender, 4/1998]
Seven Alert Sites Remain – By December 1999, therefore, there are just seven alert sites around the continental US, each with two fighters on alert. These sites are Homestead Air Reserve Base, Florida; Tyndall Air Force Base, Florida; Portland Air National Guard Base, Oregon; March Air Reserve Base, California; Ellington Air National Guard Base, Texas; Otis Air National Guard Base, Massachusetts; and Langley Air Force Base, Virginia. Only two of these sites—Otis ANGB and Langley AFB—serve the northeastern United States, where the hijackings on September 11 will take place. [Airman, 12/1999; 9/11 Commission, 7/24/2004, pp. 17]
1990-2001: NORAD Regularly Launches Fighters to Intercept Suspicious Aircraft before 9/11
Fighter jets are regularly scrambled by the North American Aerospace Defense Command (NORAD) in response to suspicious or unidentified aircraft flying in US airspace in the years preceding 9/11. [General Accounting Office, 5/3/1994, pp. 4; Associated Press, 8/14/2002] For this task, NORAD keeps a pair of fighters on “alert” at a number of sites around the US. These fighters are armed, fueled, and ready to take off within minutes of receiving a scramble order (see Before September 11, 2001). [American Defender, 4/1998; Air Force Magazine, 2/2002; Bergen Record, 12/5/2003; Grant, 2004, pp. 14] Various accounts offer statistics about the number of times fighters are scrambled: 
A General Accounting Office report published in May 1994 states that “during the past four years, NORAD’s alert fighters took off to intercept aircraft (referred to as scrambled) 1,518 times, or an average of 15 times per site per year.” Of these incidents, the number of scrambles that are in response to suspected drug smuggling aircraft averages “one per site, or less than 7 percent of all of the alert sites’ total activity.” The remaining activity, about 93 percent of the total scrambles, “generally involved visually inspecting unidentified aircraft and assisting aircraft in distress.” [General Accounting Office, 5/3/1994, pp. 4] In the two years from May 15, 1996 to May 14, 1998, NORAD’s Western Air Defense Sector (WADS), which is responsible for the “air sovereignty” of the western 63 percent of the continental US, scrambles fighters 129 times to identify unknown aircraft that might be a threat. Over the same period, WADS scrambles fighters an additional 42 times against potential and actual drug smugglers. [Washington National Guard, 1998] In 1997, the Southeast Air Defense Sector (SEADS)—another of NORAD’s three air defense sectors in the continental US—tracks 427 unidentified aircraft, and fighters intercept these “unknowns” 36 times. The same year, NORAD’s Northeast Air Defense Sector (NEADS) handles 65 unidentified tracks and WADS handles 104 unidentified tracks, according to Major General Larry Arnold, the commander of the Continental United States NORAD Region on 9/11. [American Defender, 4/1998] In 1998, SEADS logs more than 400 fighter scrambles. [Grant, 2004, pp. 14] In 1999, Airman magazine reports that NORAD’s fighters on alert at Homestead Air Reserve Base in Florida are scrambled 75 times per year, on average. According to Captain Tom Herring, a full-time alert pilot at the base, this is more scrambles than any other unit in the Air National Guard. [Airman, 12/1999] General Ralph Eberhart, the commander of NORAD on 9/11, will later state that in the year 2000, NORAD’s fighters fly 147 sorties. [9/11 Commission, 6/17/2004 ] According to the Calgary Herald, in 2000 there are 425 “unknowns,” where an aircraft’s pilot has not filed or has deviated from a flight plan, or has used the wrong radio frequency, and fighters are scrambled 129 times in response. [Calgary Herald, 10/13/2001] Between September 2000 and June 2001, fighters are scrambled 67 times to intercept suspicious aircraft, according to the Associated Press. [Associated Press, 8/14/2002]
Lieutenant General Norton Schwartz, the commander of the Alaskan NORAD Region at the time of the 9/11 attacks, will say that before 9/11, it is “not unusual, and certainly was a well-refined procedure” for NORAD fighters to intercept an aircraft. He will add, though, that intercepting a commercial airliner is “not normal.” [Air Force Magazine, 9/2011 ] On September 11, 2001, NEADS scrambles fighters that are kept on alert in response to the hijackings (see 8:46 a.m. September 11, 2001 and 9:24 a.m. September 11, 2001). [New York Times, 10/16/2001; 9/11 Commission, 7/24/2004, pp. 20, 26-27]
Between 1991 and 2001: NORAD Exercise Simulates Crash into Famous US Building
At some point between 1991 and 2001, a regional NORAD sector holds an exercise simulating a foreign hijacked airliner crashing into a prominent building in the United States, the identity of which is classified. According to military officials, the building is not the World Trade Center or the Pentagon. The exercise involves some flying of military aircraft, plus a “command post exercise” where communication procedures are rehearsed in an office environment. [CNN, 4/19/2004]
February 1993-May 1994: US Military Head and GAO Recommend Reducing Units Dedicated to Continental Air Defense
Colin Powell, the chairman of the Joint Chiefs of Staff, recommends that the number of aircraft dedicated to defending US airspace be reduced, a recommendation echoed by the General Accounting Office (GAO) over a year later. The continental air defense mission, carried out by the North American Aerospace Defense Command (NORAD), was developed during the Cold War to protect against any Soviet bombers that might try to attack the US via the North Pole. In 1960, NORAD had about 1,200 fighter jets dedicated to this task, but now its US portion comprises 180 Air National Guard fighters, located in 10 units and 14 alert sites around the US. In February 1993, Powell issues a report in which he suggests that, due to the former Soviet Union no longer posing a significant threat, the air defense mission could be transferred to existing general-purpose combat and training forces. In May 1994, the GAO issues a report agreeing with Powell, saying that a “dedicated continental air defense force is no longer needed.” The report also says: “NORAD plans to reduce the number of alert sites in the continental United States to 14 and provide 28 aircraft for the day-to-day peacetime air sovereignty mission. Each alert site will have two fighters, and their crews will be on 24-hour duty and ready to scramble within five minutes.” [US Department of Defense, 2/12/1993; General Accounting Office, 5/3/1994] NORAD will play a key role in responding to the hijackings on 9/11. By then, it will have just 14 fighters available around the US on “alert”—on the runway, fueled, and ready to take off within minutes of being ordered into the air. [Code One Magazine, 1/2002; 9/11 Commission, 7/24/2004, pp. 17]
1995: FAA Runs Hijacking Exercise; NORAD Participates
The Federal Aviation Administration (FAA) holds a training exercise based on the scenario of an aircraft hijacking, which involves a real plane playing the part of the hijacked aircraft. The exercise will be described to the 9/11 Commission in 2004 by Major Paul Goddard, who is the chief of live exercises for the North American Aerospace Defense Command (NORAD) at the time of the 9/11 attacks. According to Goddard, the exercise, held in 1995, is called “Twin Star” and the FAA invites NORAD to participate in it, “since a real commercial airliner was to be shadowed by a fighter intercept.” Goddard will tell the 9/11 Commission his understanding is that the exercise involves the entire FAA system, and the National Military Command Center (NMCC) at the Pentagon also participates in it. [9/11 Commission, 3/4/2004] Colin Scoggins, the military operations specialist at the FAA’s Boston Center on 9/11, will describe what is apparently this exercise when he is interviewed by the 9/11 Commission in 2003. He will say he believes the exercise is “joint FAA/military” and is conducted “in 1995 or 1996.” According to Scoggins, the exercise involves “a military scramble to escort a hijacked aircraft,” but the fighter jets taking part are “unable to intercept” the mock hijacked plane. [9/11 Commission, 9/22/2003 ] Apparently describing the same exercise in a documentary film, Scoggins will say, “We had run a hijack test years before [9/11] and the fighters never got off on the appropriate heading, and it took them forever to catch up.” [Michael Bronner, 2006]
December 1997-2001: Number of Alert Air Bases Inadequate to Protect against Airborne Terrorism, NORAD Commander Says
Major General Larry Arnold, who became commander of the Continental United States NORAD Region (CONR) in December 1997, fights to preserve the resources assigned to US air sovereignty (see May 19, 1997 and Late August 2001). To emphasize the need for air bases with fighter jets on alert, Arnold frequently gives a presentation describing “asymmetric” threats and including a slide featuring Osama bin Laden. As Arnold will later recall: “[W]e thought that the biggest threat to the US in the briefing that I always gave… was going to come from an asymmetric threat, from a terrorist or a rogue nation, or maybe associated with the drug cartels to some degree. The picture that we used to have on one of our slides there, dating all the way back to 1997 and 1998, was Osama bin Laden.” [Filson, 2002] Colonel Alan Scott, who serves under Arnold at CONR, will later describe the “El Paso example” that Arnold uses to illustrate the need for more alert sites. Scott says: “We had fairly large gaps between our seven alert sites pre-9/11. The largest was between Riverside, CA, and Houston, TX. El Paso, TX, was in the middle of those two alert sites. There was no perceived ‘military’ threat from Mexico. As the threat of terrorism arose, General Arnold began to use the example in his talks to various groups. The example was that if a terrorist called and said in one hour he would overfly El Paso, TX, and spray deadly gas, we would watch it live on CNN because we could not get aircraft to that location in time to stop the attack.” [Filson, 7/14/2002]
1998-September 10, 2001: NORAD Operations Center Runs Five ‘Hijack Training Events’ Each Month
At its operations center in Cheyenne Mountain, Colorado, the North American Aerospace Defense Command (NORAD) practices dealing with hijackings five times per month, on average, during training exercises. A NORAD document produced a month after 9/11 will state that the Cheyenne Mountain Operations Center (CMOC) “routinely conducts the Amazon Arizona series of internal exercises that include hijack scenarios.” Prior to September 11, 2001, the document continues, “CMOC averaged five hijack training events each month.” Further details of these “Amazon Arizona” exercises are unstated in the document. [North American Aerospace Defense Command, 10/13/2001 ] But other sources provide additional information about what they might entail.
Exercises Are ‘One of the Busiest Times’ in Operations Center – According to a 1989 NORAD document, “Arizona” exercises are a “Cheyenne Mountain Air Force Base internal system training mission.” [North American Aerospace Defense Command, 8/25/1989] And in 2004, NORAD will state that its exercises before 9/11 that include hijacking scenarios test “track detection and identification; scramble and interception; hijack procedures; internal and external agency coordination; and operational security and communications security procedures.” [CNN, 4/19/2004] According to Stacey Knott, a technician at the CMOC, “One of the busiest times” in the operations center “is during exercises.… We have the battle staff and CAT [Crisis Action Team] in here; generals and admirals are running in and out.” Knott has said that exercises at the CMOC give her “an idea what things would be like if something were to go down,” and so, “[i]f something actually did happen, we’d be ready for it.” [Airman, 1/1996]
Operations Center Is ‘Focal Point for Air Defense Operations’ – It is unclear over what period up to 9/11 the CMOC averages five hijack training events per month. It appears to be at least going back to 1998: In 2003, Ken Merchant, NORAD’s joint exercise design manager, will tell the 9/11 Commission that his office keeps computer hard drive information about NORAD exercises “roughly” back to that year. Merchant will add that he “did not believe that his office retained other exercise information, such as after-action reviews, for exercises prior to 1998.” [9/11 Commission, 11/14/2003 ] According to NORAD’s website, “the Cheyenne Mountain Operations Center provides warning of ballistic missile or air attacks against North America, assists the air sovereignty mission for the United States and Canada, and, if necessary, is the focal point for air defense operations to counter enemy bombers or cruise missiles.” [North American Aerospace Defense Command, 11/27/1999] On the morning of 9/11, members of the battle staff at the CMOC will be participating in the exercise Vigilant Guardian (see (6:30 a.m.) September 11, 2001). [Airman, 3/2002; 9/11 Commission, 3/1/2004 ]
August 14, 1998: Richard Myers Becomes New NORAD Commander
General Richard B. Myers takes over as commander in chief of the North American Aerospace Defense Command (NORAD), commander in chief of the US Space Command, and commander of the Air Force Space Command. He replaces General Howell M. Estes III. [North American Aerospace Defense Command, 6/3/1998; Air Force News, 8/19/1998] Myers will serve in these positions until February 22, 2000, when he will be replaced by General Ralph E. Eberhart. [Air Force News, 2/22/2000] On 9/11, Myers will serve as the acting chairman of the Joint Chiefs of Staff. [Myers and McConnell, 2009, pp. 10]
Between August 15, 1998 and February 22, 2000: NORAD Radar System and Control Software Inadequate, Commander Finds
At some point during his tenure as commander in chief of NORAD (see August 14, 1998), General Richard Myers expresses concerns about the adequacy of the radar system over the US, which NORAD shares with the Federal Aviation Administration (FAA) in what is called the Joint Surveillance System. Myers will later tell the 9/11 Commission that NORAD is unable to “correlate” over 50 percent of the unknown radar tracks it picks up, either because it cannot launch an interceptor aircraft in time or because it cannot deal with the tracks appropriately. Some of them disappear from radar before NORAD can correlate them with the FAA. Myers makes Pentagon officials aware of the problem, telling them, “don’t think we’re providing 100 percent air sovereignty here… we’re looking outward, and a number of those tracks are never correlated.” He will recall that in connection with the internal radar issue, “I saw a letter I put out talking about a potential terrorist issue… that’s why you would want these radars up… it’s kind of a future issue.” According to Myers, there is talk about the future potential of a terrorist threat as a rationale for “trying to get people to address the FAA/[Air Force] radar funding issue in a more robust way.” Myers also finds NORAD’s command and control software inadequate. He will tell the 9/11 Commission that the “system was very old and was contracted to be replaced, but the contractor did not perform. The issue was how many tracks the system could handle at once; NORAD kept modifying the equipment to allow more inputs but it needed a new system.” However, Myers will also confirm to the 9/11 Commission that “from a technical radar standpoint, NORAD had pretty good coastal
range, and that the activity on 9/11 was within the radar area that was accessible to NORAD.” [9/11 Commission, 2/17/2004 ; 9/11 Commission, 6/9/2004]
December 2-4, 1998: NORAD Runs an Exercise in Which Simulated Information Is Injected into Its Radar Systems
The North American Aerospace Defense Command (NORAD) conducts an exercise, called Vigilant Virgo 99-1, in which simulated missiles are injected into its radar systems, apparently similar to the way simulated information will be injected onto its radar screens for a training exercise on the morning of September 11, 2001. [US Department of Defense, 1/15/1999; Toronto Star, 12/9/2001; Arkin, 2005, pp. 546] In August 1998, Secretary of Defense William Cohen directed the commanders in chief who are responsible for the Department of Defense’s unified combatant commands to plan, carry out, and report on a series of simulated Year 2000 “operational evaluations.” [United States General Accounting Office, 6/1999, pp. 8 ; United States General Accounting Office, 11/1999, pp. 15 ] Vigilant Virgo is the first in a series of NORAD operational evaluations that are going to be held in response to this order. [US Department of Defense, 1/15/1999; United States General Accounting Office, 6/1999, pp. 2 ; Military Operations Research Society, 6/22/1999, pp. 193 ]
Exercise Tests NORAD’s Year 2000 Preparedness – The three-day exercise is intended to evaluate if NORAD’s systems are vulnerable to the Year 2000 (Y2K) computer problem, which would be caused by computers being unable to properly read dates at the start of the new millennium. [US Department of Defense, 1/15/1999; New York Times, 2/9/1999] It evaluates the capability of NORAD’s systems to track and forward information about missile and space air threats when the command’s clocks are rolled forward to January 1, 2000. [United States General Accounting Office, 6/1999, pp. 8-9 ] The exercise is a collaborative effort in which NORAD is supported by personnel, equipment, and facilities belonging to the US Space Command and the US Strategic Command. [US Department of Defense, 1/14/1999; US Department of Defense, 1/15/1999]
‘Missile Events’ Are Injected into NORAD’s Sensors – Vigilant Virgo focuses on the missile warning element of NORAD’s integrated tactical warning and attack assessment function. [United States General Accounting Office, 6/1999, pp. 11 ; Military Operations Research Society, 6/22/1999, pp. 193 ] It involves “well over 30 missile events” being “injected” into NORAD’s sensors, according to Lieutenant Colonel Warren Patterson, a member of the Joint Staff Year 2000 Task Force. These simulated events involve data that is injected “as though it [is] being sensed for the first time by a radar site,” Deputy Secretary of Defense John Hamre will later describe. Some of the simulations involve mass attacks, while others involve attacks by a single missile. [US Department of Defense, 1/15/1999] The Y2K preparedness of the entire ground radar array network is analyzed during the exercise. [Bulletin of the Atomic Scientists, 3/1999]
Exercise Finds No Vulnerabilities in NORAD’s Systems – Vigilant Virgo will be considered a success. The exercise will find that there is “no degradation in any of the systems, whether they were in the Year 2000 environment, the virtual Year 2000 environment, or whether they were in the real world, 1998 environment,” Patterson will say. “We are highly confident now, at this point, that CINC [commander in chief] NORAD can do his early warning mission,” he will conclude. [US Department of Defense, 1/15/1999]
Exercise on 9/11 Will Use Simulated Radar Information – NORAD is the military organization responsible for monitoring and defending North American airspace. [9/11 Commission, 7/24/2004, pp. 16; Department of National Defence, 7/25/2017] Personnel at its Northeast Air Defense Sector (NEADS), based in Rome, New York, will be responsible for coordinating the military’s response to the 9/11 hijackings. [Shenon, 2008, pp. 203] It will be conducting an exercise on the morning of September 11, 2001, which, like Vigilant Virgo, involves simulated information being injected onto its radar screens (see (9:00 a.m.) September 11, 2001, 9:34 a.m. September 11, 2001, and 10:12 a.m. September 11, 2001). [Toronto Star, 12/9/2001] NORAD will conduct a follow-on exercise to Vigilant Virgo from February 15 to February 28, 1999, called Amalgam Virgo 99-2, which will involve a comprehensive evaluation of its systems for aerospace control, air warning, missile warning, and space warning. [United States General Accounting Office, 6/1999, pp. 11 ; Arkin, 2005, pp. 253-254] Whether that exercise will involve simulated information being injected onto radar screens is unclear.
