9-11: AA 77; independent investigation, validation and verification

Addendum, Feb 20, 2011

Warren Stutt has updated his AA77 FDR output files.

Addendum, Feb 19, 2011

An additional piece of research and analysis has come to me attention that adds to the work cited in my original post.  John (not Commission) Farmer has provided a link to a definitive, primary source-based, analysis of radar pertinent to 9-11.  His paper is titled, “Radar and NTSB Time Normalization for 9/11 Data Sources.”

Here is Farmer’s lead paragraph:

“Perhaps one of the most contentious aspects of the analysis of American Airlines Flight 77’s (AAL77) flight path is the reconciliation of the radar data released by the U.S. Air Force’s 84th Radar Evaluation Squadron (84 RADES), the Federal Aviation Administration (FAA), and National Transportation Safety Board (NTSB). However, this should not be the case since alignment of the individual data sets is rather straight- forward in the case of AAL77. Also, the abundance of data from such a wide spectrum of sources and measurement systems, from take-off to within seconds of the termination of flight, gives a complete and unequivocal historical record.”

Farmer’s work is technical and, based on my all-source knowledge of the radar issue, is definitive.  Taken together with the other sources I cited earlier the public has an articulate, rigorous, and nearly complete story of AA 77 and the Pentagon, one constructed independent of the work of the Commission.

This body of work is a logical extension of the work of the Commission and the Congressional Joint Inquiry before it.  The work stands on its own merit and can be replicated, a measure of its validity.  Historians and researchers now have available a body of work, one that can be used and cited with a high degree of confidence in its accuracy.


The purpose of this article is to acknowledge responsible research and investigation concerning AA 77 and the Pentagon.  A body of work has now been completed largely independent of the work of the Commission and the Joint Inquiry before it.  Taken together, three independent efforts comprise a valuable publicly available source of accurate information.

The three are the work of Legge and Stutt in reconstructing the data from the AA 77 flight data recorder, the work of the American Society of Civil Engineers in assessing the damage to the Pentagon, and the work of Creed and Newman in detailing the rescue and recovery efforts by first responders.  We start with the recent web publication of the work of Legge and Stutt

Frank Legge and Warren Stutt

Warren Stutt, a knowledgeable and dedicated researcher, spent months obtaining and analyzing the most critical and accurate primary source information available, the data from the Flight Data Recorder (FDR) for AA 77.  The result of that work, “Flight AA77 on 9-11: New FDR Analysis Supports the Official Flight Path Leading to Impact with the Pentagon,” resolves multiple issues that arose because the National Traffic Safety Board’s own work did not account for the final seconds of the flight of AA 77.

Legge and Stutt conclude that: “Previous analyses were…confounded by uncertainty of the position of the last data point; failure to consider possible calibration errors in the pressure altimeter data, caused by high speed and low altitude; and false information in the NTSB flight animation.  The recent complete decoding of the FDR file has enlarged and clarified the information available and has thereby enabled resolution of the contradictions. It is clear that this file supports the official account of the course of flight AA 77 and the consequent impact with the Pentagon. The file thus also supports the majority of eyewitness reports.”

The words “complete decoding” are important.  The authors took the raw data from the FDR and reconstructed every frame of data, to include data previously thought not to have been recorded.  Their dedicated effort completes the work of the National Traffic Safety Board (NTSB) which left the technical story hanging.

However, their work only takes the AA77 story up to the point it impacted the Pentagon.  For the rest of the story we turn to two previous studies, “The Pentagon Building Performance Report” and the Creed/Newman book Firefight: the Battle to save the Pentagon on 9-11. We begin with the building performance report.

The Pentagon Building Performance Report (PBPR)

The Performance Report, [PDF file available at this URL: http://fire.nist.gov/bfrlpubs/build03/PDF/b03017.pdf (copy/paste into browser] published in January 2003 under the auspices of the American Society of Civil Engineers and the Structural Engineering Institute, provides a detailed technical analysis of what happened once AA 77 penetrated the building.

According to the authors the purpose of the report was to “…examine the performance of the structure in the crash and the subsequent fire for the benefit of the building professions and the public.”  Their work extends the trajectory established by Legge and Stutt into the Pentagon and describes the resultant damage. 

Together, the two analyses so far discussed conclusively document the final moments of AA 77 and provide a technical account of what happened.  Although the Performance Report  did consider some eye witness testimony the human aspect of the story has best been told by Creed and Newman.

Creed and Newman

In their 2008 book, Firefight: Inside the Battle to Save the Pentagon on 9/11, Creed and Newman tell the story of the emergency response, what happened in the immediate aftermath once AA 77 slammed into the Pentagon.  According to the dust jacket summary, the authors were “Granted unprecedented access to the major players in the valiant response efforts, [the authors] take us step-by-step throught the harrowing minutes, hours, and days following the crash…into the Pentagon’s western facade.

According to Creed and Newman, “The instant its nose struck the outer wall of the Pentagon, Flight 77 ceased to be an airplane.”  At that moment physics [and chemistry, the laws of science] took over.  It became a “roaring mass of fluid and debris…a tidal wave…”  “The Pentagon finally arrested the forward movement of Flight 77. The mass plowed through the C Ring and blew a round hole, about 12 feet in diamenter, through the ring’s inner wall.”  From the moment of impact, the entire event had taken place in eight-tenths of a second.”

Independent of the 9-11 Commission

The three investigative efforts described, taken together, tell a complete story of the last moments of flight AA 77 and the Pentagon.  There work can be replicated and it stands apart from the work of the 9-11 Commission and the Joint Inquiry.  The work of Legge, Stutt, Creed, Newman, and the authors of the ASCE report is definitive and validates and verifies the work of the 9-11 Commission.

Moreover, it provides an independent baseline for assessing the multiple eye witness and participant recall accounts.  Some researchers have speculated, based on eye witness accounts that somehow something quite different happened to both AA 77 and the Pentagon.

Creed and Newman have this to say concerning eye witness accounts in their Epilogue:  “In addition to the documentary evidence we’ve cited as source material, we have relied on the memories and personal records of more than 150 people…Memories, of course, can be incomplete and faulty…We checked personal recollections against official documents wherever possible…”

Eye Witness Accounts

Eye witness and participant recall accounts are important but only when validated and verified by primary sources and secondary information.  Given the complete story of AA 77 and the Pentagon we can now add to the account an exceptional eye witness account, that of Penny Elgas.  Her detailed, articulate, and reflective narrative is consistent in its detail and provides a vivid picture to complement the technical work of Legge and Stutt.