9-11: A Framework for Analysis


This article was updated on April 9, 2012, in order to add primary source audio to establish what was known and when about the impacts of AA11 and UA175 with the World Trade Center.  All the added material is at the end of the article.

Original Article

The 9/11 Commission and the Congressional Joint Inquiry before it determined that 19 terrorists in four groups  hijacked four commercial aircraft to use them as guided missiles to attack four buildings on September 11, 2001. Three attacks were successful; the fourth thwarted by passengers aware of their probable fate.  The Inquiry and Commission reports were published in the Spring 2003 and Summer 2004, respectively, and are generally accepted as an accurate accounting of what happened that day and in events leading up to that day.

The Commission and the Joint Inquiry gathered and considered a large body of evidence that considered the terrorist attack and the events leading up to the attack. In addition to pre-attack evidence and primary source evidence about the attacks, the Commission also examined post-attack information.

The dates and times in the following chart provide one way of defining the  pre-attack, attack and post-attack phases.

Phase Begins Ends
Pre-Attack Feb 26, 1993 5:45am Sep 11, 2001
Attack 5:45am 10:03am
Post-Attack 8:46am Present

The starting date for the Pre-Attack is the date of the first terrorist strike on the World Trade Center. Depending on one’s interest, different starting points can be taken—the bin Laden Fatwah, for example. The Pre-Attack ends as soon as Atta and one accomplice enter the National Airspace System (NAS) in Portland, Maine; the attack has begun. The attack ends when United Airlines Flight 93 (UA 93) plummets to ground near Shanksville, PA.

The commencement of the attack can be described in military terms. The Commission established the scheduled takeoff times of the four hijacked aircraft to be:

7:45 AA 11

8:00 UA 175

8:10 AA 77

8:00 UA 93

That establishes a line of departure (LD) at Boston Logan Airport between 7:45 and 8:00 a. m. for the attack against the World Trade Center and an LD at two locations, Newark Airport and Dulles Airport between 8:00 and 8:10 for the attack against Washington D. C. It is speculative but the timing suggests that the overall attack plan was synchronized with the four impacts to occur in a short span of time, but with the northern attack to precede the southern attack.

This description in military terms now allows us to place Atta’s departure from Portland Airport in perspective. Colgan Air flight 5930 departed at 6:00 a. m., on time. That became, then, an initial or preliminary line of departure. Actually, Atta entered into the National Airspace System at 5:45 a.m. when he passed through security and was free to board.

We can further speculate that Atta established that tactical procedure as a backup plan;  he only needed one plane to hit one target for the day to be a success. Anything else was simply value added. So, he, together with one accomplice, traveled as a team to enter the system at a remote location, with a backup plan to attempt to hijack AA 11 with just a two-man team. There is one piece of evidence that supports this speculation. Atta was, according to a Commission Staff Report of August 24, 2004, visibly upset when he learned he would have to pass through screening a second time at Logan Airport.

As it turned out, a backup plan was not needed. According to the same Staff Report. Atta received a phone call at 6:52 a.m. from Terminal C, the departure terminal for United Airlines Flight 175 (UA 175). By the time that three minute call ended all 10 hijackers for the attack against the World Trade Center had passed through security and were in the NAS. In military terms, they achieved tactical superiority; they were inside the decision cycle of their enemy. They were well on their way to demonstrating mastery of a key principle of war; surprise.

Surprise was achieved between 8:46 and 8:47 a.m.; the Post-Attack phase began with the impact of AA 11. It overlapped the Attack phase and it continues to this day. From that moment personal recall started and the reporting and telling of events were shaped by what people thought they saw, what they recalled doing, and what the media reported.

Added Information

How News of AA11 and UA 175 was Received

La Guardia and Newark Towers

La Guardia Tower, Class B airspace position,  was the initial Air Traffic Control facility to learn of the first collision at the World Trade Center.  The controller was in routine communication with a helicopter, Bravo Quebec, whose description of the event was brief.  That first description was that it “looks like somethin’ just collided [with the World Trade Center].”  0847 Looks Liike Something Just Collided 

Shortly thereafter, the La Guardia controller compared notes with a colleague at Newark Tower.  The latter reported that there was a huge amount of smoke coming from the top ten floors. “All of sudden a huge plume of smoke came out of the World Trade Center.  0848 Newark Huge Amount of Smoke

At that same time, 8:48,  an unidentified plane asked the Newark Tower Ground Control position  about the “smoke coming off the World Trade building.”  The controller advised that they were “calling the port right now about it , it just started.”  The plane reported that they saw it, “a couple minutes ago, big puff of smoke.”  The controller advised that “they werenot sure if something hit it or something happened inside.” 0848 Calling the Port Right Now

A few seconds prior, acknowledgement of a fire at the World Trade Center was recorded at the Newark Tower Local Control position.  That controller also told an unidentified plane that the Port Authority had been called. 0847 Fire at the World Trade Center

At 8:55, a law enforcement helicopter reported in with La Guardia and directed that all traffic above 2000 be diverted, “we possible have a plane into the World Trade.”  0855 Posslble Plane into the World Trade

Shortly after 9:00, the La Guardia controller compared notes with Teeterboro and speculated that “personally, I don’t think it was an airplane.”  He soon corrected the record in a discussion with, first, the police helicopter (PD 14) and then a news helicopter (Chopper 4)  The police helicopter reported “unknown size [of the airplane] at this time.”  The news helicopter reported, “can’t tell  how big [size of the airplane] it is right now.” 0900 Helicopter reports police and news 

At 9:03 the  La Guardia controller received a report from an unidentified caller [likely PD 14] that a 737 [UA175] hit the World Trade Center.  0903 A 737 Just Struck the World Trade Center

Immediately thereafter, La Guardia worked with the police helicopter to ensure that all aircraft under La Guardia control were exiting the airspace. That effort spanned two minutes during which it was not clear from observers in the sky or at La Guardia what planes and of what size had struck the two towers.  0904 La Guardia Traffic Control Sequence

At Newark Tower, the Local Control position acknowledged that they saw the impact as it occurred.  Within a minute the controller advised, “everbody just stand by.”  Within another minute he took action to stop all takeoffs;  “just stand by, there is a situation, just, all departures are stopped, stay with me.  Everybody just monitor my frequency, please don’t call me, I will call you.” 0903 Yes I Saw It

It is clear from this series of conversations recorded at New York area towers that observers closest to the scene did not have accurate situational awareness.  The helicopters in the vicinity and the Class B airspace controller  knew only that two aircraft, possibly 737s had flown into the World Trade Center and that they had an emergency situation on their hands.  And that became the focus of attention at that level.

The next entity in the air traffic control chain-of-command was New York TRACON and we next look at the situational awareness at that level.


New York TRACON first learned of a problem with AA11 shortly after 8:40 when it joined a telecon with Boston Center linked by the FAA’s Air Traffic Control System Command Center (Herndon Center).  That call was taken at the Traffic Management Unit, Departure Director position (TMUDD).  The call was a continuous exchange of information, first with Boston Center and Herndon Center, and then New York Center (ZNY), which broke into the conversation. The exchange lasted nearly three minutes.

The fear was that AA11 would land at Kennedy without advanced notice. However, the ZNY caller reported that he had learned that the aircraft was still at 29,000 feet and would bypass Kennedy.  Here is the conversation as recorded at New York TRACON. 0840 ZBW TRACON ZNY AA11 notification

At 8:51,  a caller asked for assistance in locating AA11 on the TMS (traffic management system).  the TMUDD specialist reported that he had lost the plane on radar and at 8:52 learned of the news.  “Hang on, what’s that?”  A background voice responded,  “An airplane crashed into the top of the World Trade Center.”  The response was at once cryptic and clear.  “What?”  “Wow?”  0852 Hang on Whats That 

Immediately thereafter, the Operations Manager in Charge of New York Center, Mike McCormick, called New York TRACON.  That nearly two minute call is important for three reasons.

  1. All key senior managers in the New York area; McCormick, his next in command, Bruce Barrett, and the Operations Manager in Charge at Newark TRACON, Bob Burch, participate.
  2. The initial alert about UA175 by the New York controller to Bruce Barrett is heard in background (amplified)
  3. Initial reporting information became conflated and confused at New York Center, New York TRACON, and at least one of the area towers, Newark.

McCormick stated that two things were going on, but he had not assimilated that UA175 was yet a third thing.  He conflated the alert about UA175 to pertain to AA11 as one thing.  The unidentified plane that struck the World Trade Center was the other thing.  Here is that call as recorded at New York TRACON. 0853 McCormick, Burch, Barrett in real time 

The TMUDD position then took two calls in sequence which, taken together, show the uncertainty in the National Airspace System.  The first caller, a traffic manager from U.S. Air called to see if the incident at the Word Trade Center involved one of their aircraft.  the New York TRACON traffic manager, Carl, said “we don’t know [what happened]” and “I guess we’ll have to turn on CNN to find out.”

The second caller was Wanda, a traffic manager from Herndon Center, who inquired about the impact on the air traffic control system.  Carl told her, “we’re just trying to figure out what actually occurred and what is going on, and what needs to be done.” 0855 TRACON called by US Air and Herndon Center