Chaos Theory: UA 93; disruptive feedback, an interesting analysis


The purpose of this short article is to document for the record an analysis of the final chapter in the UA 93 story.  In the language of chaos theory, UA 93 became disruptive feedback once Cleveland Center entered a new flight plan for the hijacked plane in the air traffic control system, with destination Reagan National Airport.  The disruptive feedback that United 93 was still in the air confounded the national level at the time and in the accounting in the aftermath.

UA 93 lost on TSD at 1028 EDT

Here is a clip from the F2 Position, National TRACON (1 DCA 101-102 Tape 1-2 F2 1327-1450 UTC, as archived by NARA as part of the Commission files)  The F2 Position controlled the Andrews fighters once airborne.  As of 1028 the F2 Position knew that there was no target associated with UA 93. 1028 UA 93 not in system

In previous articles I have dealt with disruptive feedback, primarily in terms of the false report of AA 11 still airborne and the erroneous report that Delta 1989 had been hijacked.  In the language of chaos theory feedback is disruptive if it results in “a gain” to a system.  Concerning events of 9-11 that “gain” was the addition of planes the either had ceased to exist or were not in distress.  By that measure, the introduction of a new flight plan for UA 93 by Cleveland Center became disruptive.  That action by Cleveland Center was beneficial to air traffic control, specifically Cleveland and Washington Centers.  It was not beneficial to the system at large as we shall see.

Here is a link to analysis done by Brian Stark (Boone870 on the web) some months ago.  That analysis included the audio clip from National TRACON.  Stark’s analysis remains the definitive work on the UA 93 Traffic Situation Display (TSD) story, as told in the primary source and secondary information material of the day, supplemented by later recall by Transportation Secretary, Norman Mineta. 

(Note: the link in the last slide is no longer active)

Even though UA 93 was reported down with an impact time of 1003 EDT the flight plan was displayed and updated in the Traffic Situation Display (TSD) system until the flight “landed” at 1028 EDT at Reagan National.  It was that “landing” that was concurrently reported to National TRACON by an FAA caller who was watching a TSD display. (In context, the FAA caller was likely either Baltimore or Dulles TRACON)

It was the “approach” to that landing that became the threat to the National Capital Region, as updated to Secretary Mineta by Monte Belger, according to Mineta’s interview the next year with MSNBC.

It would be nearly ten more minutes before the first Andrews fighter took off in pursuit of an airplane that no longer existed, in fact or in projected flight plan.

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