Ground Zero
By C.J. Kennedy, Fri Oct 05 00:00:00 GMT 2001

A report from Manhattan: How wireless technology was used to search for survivors after the World Trade Center disaster.

Living a mile across the East River from the Trade Centers, I watched the twin towers burn from the third floor window of my daughter's school. Outside on the Brooklyn sidewalk an old woman was wailing, and a young man was walking back and forth, shaking his arms in the air. "We are under attack!" he shouted. "You don't understand we are under attack!"

After my wife and I picked up our daughter from her school we walked two miles back to our house. Ash and smoke swirled through the air and coated the cars with a light snow. The subways had stopped, the busses were too crowded to board, and anyway the traffic wasn't moving. The streets filled up with people trudging along like refugees - glancing behind them at the burning buildings. Some pedestrians pressed the touch pads of their mobile phones and held them to their ears to check on friends and relatives.

No signals got through.

Major wireless transmitters for Manhattan had been located on top of the World Trade Centers. When the phone companies redirected calls through other transmitters, the networks were so jammed that even people using landlines by pay phones could not through. On one quiet morning in New York City the chatter of modern technology had been silenced.

Twenty-four hours after the World Trade Center attack various news agencies reported that survivors had called from within the rubble - using cell phones and pagers, or typing messages by laptops. Some victims had been rescued because of their wireless device. Telecommunications experts hurried to ground zero, set up the latest wireless technology, and searched as buildings burned around them. From satellite triangulation to radio frequency sniffers, the latest technology was used. The new team, named the Wireless Emergency Response Team (WERT), included technicians from companies such as Bell South, Lucent, AT&T Wireless, Nextel, Verizon Wireless, Sprint PCS, Voicestream, Arch Wireless, Motorola, Telecordia Technologies, Nortel and SkyTel.

Technology helping the rescue

The wireless rescue effort by WERT was divided into three parts. At the most basic level Bell South and FEMA (the Federal Emergency Management Agency) set up a phone bank for collecting phone number of people missing in the disaster.

WERT gathered information from members of the public who either received contact from a mobile device of a missing person or had mobile phone numbers of people missing. "What we did on Friday afternoon was to set up employees and volunteers," says Peg Bernhardt, spokesperson for Bell South. "Since then we have received over 4,000 calls. There have been two types. The majority are people with cell phone or pager numbers of those missing, and some have been from people who think they might have received calls from people trapped." Although this call center has not aided directly in saving anyone in the rubble, it has managed to connect families with people who were injured or near the accident site.

The second effort by WERT was to locate people using satellites to triangulate on signals. A Verizon spokesperson said that this team left after twenty-four hours. Triangulation can only pinpoint devices within 60-70 yards, offering only some specific information.

The third effort consisted of using Radio Frequency (RF) Sniffers at ground zero to search for signals. RF Sniffers have been used before to check wireless signals before, but never to locate people, states Peter Settles, spokesperson for Lucent. "There was a separate effort to detect frequencies coming out of the rubble, to see if there were any signals coming out," he says, describing the operation in the financial district of New York City. "We came to the site with test equipment in hand. This isn't new technology, but it was certainty a new application for the technology."

RF Sniffers are not able to locate a signal exactly, but they are more precise than satellite triangulation. "We cannot specifically pinpoint a signal," says Peter Settles. "You are not going to locate a signal within ten feet or so. But if we did detect something then the rescue efforts would search in that area." Still, they found no one. Only a small percentage of people in the collapsed buildings were even found. After the first four days, no one was pulled out of the rubble.

Desperate effort with frustrating results

The latest wireless technology could not detect what was not there - life in the wreckage. During the second weekend of the rescue effort, twelve days after the attack, the WERT team left ground zero for the crews to clean away the steel girders and the shattered concrete.

But the Wireless Emergency Response Team has not given up. "We are still doing basic monitoring," says Pete Settles. "We are not right at the site anymore. But we are monitoring the scene. Looking when the crews move steel to see if we get a signal. I don't want to get anyone's hopes up. We haven't found anything. We just tried to do what we could."

Lesson learned for future rescues

During the first few years of the emerging mobile industry, wireless technology has been criticized as either technology for technologies sake, or too focused on the bottom line. Location services have been promoted as a mobile "killer-app." For nearly two weeks after the WTC bombing they were seen in lower Manhattan as a "life-app."

The percentage of people using cell phones and pagers is growing and location technology is improving. The wireless industry should be able to assist again in finding people during other disasters. "I don't know if WERT will remain in place as a team," says Peter Settles. "But the lessons we learned here will be used in the future."

WERT should continue as a permanent team; it has been the greatest humanitarian use of mobile technology to date.

C.J. Kennedy is currently the senior staff writer for, and has covered the mobile industry for M-Business Magazine, The Wireless Developer Network, Wireless Business & Technology, Wireless Related, and The Industry Standard.