Analysis of 9/11 Pager Data Paints Chilling Picture

Desperate pleas for friends, family to call home were most common

An analysis of more than half a million pager messages reportedly sent on Sept. 11, 2001, provides a chilling narrative of the events as they unfolded on that fateful day.

"Please call home" was one of the most consistently used phrases in the messages, according to an analysis of data released by WikiLeaks last week.

The nonprofit activist group published 570,000 pager messages sent on Sept. 11 in an effort to "lead to a more nuanced understanding of the event and its tragic consequences." Now scientists are creating digital tools to make better sense of them.

Many of the messages aren't related to the attacks, but others clearly come from workers stuck in the towers, government officials inside the Pentagon and first responders in New York, Washington and Pennsylvania. The objective is to isolate and analyze the relevant ones.

The new tools weave a disturbing tale of what went on as the nation suffered the worst terrorist attack in history from the perspective of those on the front lines – emergency personnel, workers in the Towers, and families frantically trying to reach their loved ones.

One data visualization researcher, Jeff Clark, crafted a "word cloud" of sorts to dissect the messages. Clark analyzed 100 key phrases that sum up the events on that fateful day. Focusing on the time period from 8 a.m. until 8 p.m. on Sept. 11, he designed a video in which the phrases used most frequently pop out in larger text and the text brightens during times of high usage.

"This phrase burst visualization is basically a word cloud where the brightness of the words varies according to how prominent the words were during specific periods of time," Clark writes of of his research.

Clark also organizes the data in a timeline that produces a narrative of the events by putting key phrases in order of the time they most appeared in messages on Sept. 11.

"I recognized the pager data was very much like Twitter data, because it's basically a time stamp with a bit of text," Clark told The New York Times.

For example, the phrase "plane has crashed" was used most often at about 9 a.m., less than an hour after the hijackers flew two plans into the Twin Towers. "Unconfirmed reports" was also a common phrase at that time, as media scrambled to keep up with the developing events. Four of the most consistently used phrases throughout the entire day were "please call home," "call me ASAP," "call your mother" and "call your wife" as desperate families tried to make sure their relatives who worked in or near the World Trade Center had gotten out safely.

At about 8 p.m., the timeline demarcates a tangible shift from the breaking news to the aftermath of the terrorist attacks, with popular phrases consisting of things like "presumed dead," "police officers missing" and "Osama bin Laden."

The validity of the pager messages cannot be confirmed, in part because WikiLeaks refuses to disclose where it obtained the data. Programmers have said the pager data is the only information they've been relying on to conduct their analysis, but their findings have nonetheless been telling.

Another programmer, Colin Keigher, took a different approach. Keigher developed a searchable database of the messages to make them easier to sift through than the 40-megabyte file in which they were initially presented, according to the Times.

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