Statistical Consultants Ltd

Text-Mining of US Pager Messages from 11 September 2001

Graphs, Text-Mining, Statistical Programming

Date posted: 2 December 2011

Brief Timeline of the 9/11 Attacks

8:14 AM	Flight 11 fails to heed air traffic controller's instruction to climb to 35,000 feet.
8:42 to 8:46 AM (approx.)	Flight 175 is hijacked.
8:46 AM	Flight 11 crashes into 1 WTC (North Tower).
8:50 to 8:54 AM (approx.)	Hijacking begins on Flight 77.
9:03 AM	Flight 175 crashes into 2 WTC (South Tower).
9:28 AM	Hijackers storm the cockpit on Flight 93.
9:37 AM	Flight 77 crashes into the Pentagon.
9:59 AM	2 WTC (South Tower) collapses.
10:03 AM	United Airlines Flight 93 crashes near Shanksville, Pennsylvania.
10:28 AM	1 WTC (North Tower) collapses.

Text-Mining of Pager Intercepts

A collection of US pager messages from 11 September 2011, are available as text files on Wikileaks:
http://911.wikileaks.org/files/index.html

The messages begin at 3:00 AM on 11 September 2001, and finish at 3:00 AM the following day. Each text file covers a 5 minute period.

The following graphs show the frequency of messages and certain keywords over that time period. The data displayed in the graphs, were extracted from the text files by programming.

Searches for each keyword weren’t limited to whole words and were case insensitive e.g. hijacking, hijacker, hijacked, HIJACK, Hijack, and hijack counted towards the total number of times the word 'hijack' was mentioned.

Total Message Counts

Keyword Counts: terror

The few instances of the word ‘terror’ in pager messages received before the terrorist attacks occurred, were from the joining of the words ‘detect’ and ‘error’ to form ‘DetectErrror’.

Keyword Counts: plane

Keyword Counts: hijack

The word ‘hijack’ was mentioned in a message before the first hijacking occurred. On closer inspection, the message was a news headline about the arrest of Patrick Dolan Critton, who hijacked a plane in 1971 and was a fugitive for almost 30 years. It is a very interesting story, but was overshadowed by the events of 9/11. A New York Times news article about it can be found here.