When Communication Systems Fail

On September 11, 2001, much of the telecommunications infrastructure in lower Manhattan was destroyed. The public and private radio networks used by the police, firefighters and emergency personnel were limited in their effectiveness because of catastrophic infrastructure damage. This severely limited the ability of emergency personnel to communicate effectively, thereby exacerbating the difficulties inherent in crisis management.

On September 18, 2002, The New York Times reported that 21 minutes before the second tower collapsed, police helicopters were hovering near the tower to check its condition. A pilot radioed: “About 15 floors down from the top, it looks like it's glowing red.” Seconds later a second pilot radioed, “I don’t think this has too much longer to go. I would evacuate all people within the area of that second building.”

That knowledge never reached the emergency personnel. This interoperability problem contributed to the failure to inform firefighters and police of the tower’s imminent collapse. The problem was most apparent when Mayor Rudy Giuliani attempted to coordinate the efforts of emergency agencies by speaking into an ad hoc assortment of microphones and radios.

Good communications are essential in any emergency. Today, the primary means of communication are the public switched network, cellular, broadband, and private radio networks. Landlines have the greatest network capacity, but their fixed location and lead time for installation make their use impractical in emergencies. Even with their redundant network capability, landlines are subject to blocking when extremely large volumes of traffic occur unexpectedly. For example, after an earthquake on the West Coast, it is not unusual for residents of the area to experience busy signals for hours as the result of blocking in an overloaded network.

The fastest-growing method of communication is the public cellular network. The wireless spectrum is limited and usage is growing, so it is not uncommon to experience delays and blocking during peak periods. Blocking occurs most often during emergencies when call completion is most important. On September 11, 2001, in New York City, more than 75 percent of the wireless calls were blocked. On that same day in Washington, 50 percent of the calls were blocked.

When emergency personnel, various media, and the cell-phone-equipped public converge at disaster sites, it is no wonder the cellular network experiences blocking almost immediately. While the telecommunications industry has established standards for the prioritization of service to emergency personnel, this action has not resolved the problem.

The public switched network has built-in redundancy and can reroute a majority of the traffic around a cable cut or central office failure. Cellular and PCS networks are much more fragile. An inoperable tower, base station or antenna means that thousands of people may lose coverage in a specific geographic area. The trend is for carriers to increase the strength of the point of presence (POP), particularly in metropolitan areas, rather than to create new POPs. This network architecture may be more cost effective, but it creates a brittle network that is more likely to suffer major outages.

The blackout of August 2003 demonstrates the viability of relying on cellular telephony for priority access or mission-critical communications. The cellular networks proved unreliable, since their battery backup systems are effective only for short power outages, and many transmitters were left without power after a short time. Even after electrical power was restored, call volumes of four times the norm contributed to many calls being blocked.

Narrowband personal communications service (PCS), also known as wireless messaging, may provide an alternative means of communication that can be used across all emergency departments and public agencies to provide mission-critical communications. Narrowband PCS is a two-way wireless short-messaging communication system that has been slow to develop because of the financial weakness in the telecommunications industry, and the popularity of digital cellular and broadband PCS. However, narrowband PCS is more reliable and more effective than the current voice networks used by many first responders.

Wireless messaging is proving to be a viable supplement or back-up for voice communications, and it may prove useful for homeland security. Narrowband PCS has network system features that should be of interest to all emergency personnel. Of particular interest is a feature called incommunicado delay time, which will force registration of the mobile user until the message is delivered. If the mobile user’s messaging device loses contact with the network for longer than the incommunicado delay time (set by the system administrator), the mobile device contacts the network and checks in, allowing the pending message to be sent. If the user’s device loses contact for a period less than the incommunicado delay time, the network searches for the device until it finds it and then sends the holding message. With a private radio or cellular system, by contrast, a voice call might be made to an emergency worker in the basement of a building. If the radio signals cannot penetrate to the worker’s location, the radio or cellular phone does not recognize the failure. The call is simply not received, and the worker has no idea someone is trying to communicate with him.

Simulcasting allows wireless messaging to transmit duplicate signals from multiple locations in a specific geographic area, thereby increasing the probability that a mobile user will receive the signal. Simulcasting is particularly effective in achieving excellent in-building penetration, since signals originate from different locations and have a better probability of penetrating structures at various angles through windows, doors, and walls.

Confirmation of message receipt can be requested to ensure that the message was successfully received or, if necessary, to resend the message. Message confirmation may be broken down into two features: (1) message delivery to the mobile device and (2) message read by the user. Additionally, narrowband PCS provides enhanced location ability using GPS technology. The system provides GPS fixes in difficult environments, such as in high-rise buildings.

The network features mentioned above should be enough to warrant a thoughtful consideration of wireless messaging as a component of a comprehensive communication network. Of course, there is a negative side: Communications occur via text messages. While this is not a perfect match to the needs of emergency responders, let us not ignore the good, in search of the perfect, particularly when lives are at stake.

One final point: Technology is not a silver bullet. No technology will ever solve all of the communications problems facing emergency responders. Organizational and cultural issues must be addressed to achieve the maximum benefit of any technological enhancement. We owe our police, firemen, and emergency medical teams the best equipment and communications systems we can provide.

Bob Wynn is the former director and state chief information security officer for the state of Georgia. His 20 years in the security field include experience in senior security management, infrastructure protection, computer crime investigations, policy writing, and achieving compliance with federal regulations, such as HIPAA and GLBA. For six years, Mr. Wynn has been an instructor at the FBI National Academy in Quantico, VA, specializing in cyber-terrorism, trends in computer crime, and the behaviors and the motivations of computer-aided criminals.

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