Rescue 21: Coast Guard’s modernized national distress call system

The U.S. Coast Guard is bringing its outdated National Distress and Response System into the 21st century with a new system that betters its ability to detect and pinpoint mayday calls and coordinate rescue operations.

Rescue 21 represents a significant leap forward in technology over the legacy VHF system installed in the 1970s.

Among the biggest advantages is its compatibility with Digital Selective Calling (DSC), which transmits a vessel’s name, location and nature of distress in conjunction with a GPS and Maritime Mobile Service Identity (MMSI) number. Rescue 21 also gives the Coast Guard radio direction-finding capability for non-DSC-enabled vessels, and will close 88 known coverage area gaps identified in the existing system.

“We took a look at the last 12 or 15 years or so, and found there were a couple of rather high-profile cases … that got some people thinking that we needed to do something,” said Eugene Lockhart, the Coast Guard’s acquisition project manager for Rescue 21.

It began as the National Distress and Response System Modernization Program, he said, and after a bidding process, Arizona-based General Dynamics C4 Systems was selected to design and support the new system.

“They brought in the name Rescue 21, and that’s what we’ve been running with ever since,” Lockhart said.

The system covers 42,000 nautical miles of U.S. coastline, certain interior waterways, and the Great Lakes, Guam, Hawaii and Puerto Rico, with 350 towers to be spread out across 46 Coast Guard sectors. A modified Rescue 21 system planned for sectors in Alaska and western rivers regions will have limited direction-finding capability and rely on DSC.

The first sectors came online in 2005, in Atlantic City, N.J., and the Delmarva Peninsula. The first life was saved with the system in November of that year. Since then the Coast Guard has reshuffled its sectors, but 26 are complete and online.

“Even with missing towers, those sectors have better capability than with the legacy system,” said Mike Monteilh, General Dynamics’ engineering manager for national communications and homeland security. “We try to find the best tower sites based on location, how high we can get and environmental impacts. A lot of our effort with the Coast Guard is determining where’s the best place to put a tower so we can get the best coverage.”

Tower location is critical to Rescue 21. Each tower contains directional antennas that measure the strength of radio waves — if a broadcast is within “sight” of two towers, broadcast location can be pinpointed to within two degrees of accuracy.

“Eighty percent of the coastline can see two towers coming in,” Monteilh said. “You draw a line from each, and where they intersect is where (the broadcast) is coming from.” That means signals can be located to within about seven-tenths of a mile, which narrows a search area considerably.

The direction-finding ability also helps eliminate human error. Lockhart cites a recent distress call in New Jersey in which mariners going into the water from a boat on fire reported a location taken from their GPS that didn’t correlate with the direction-finding system.

“What we suspect is that he was reading a waypoint off the GPS (rather than his current location),” he said. “Our direction-finding system pegged them 10 miles off their reported location.”

Lockhart said the time saved by not having to search an empty location may have meant the difference between life and death.

An added bonus of direction-finding is the ability to find and prosecute hoax callers, which cost taxpayers hundreds of thousands of dollars each year and pull resources away from legitimate distress calls.

“When a call origination point is over land, you know something is up,” Lockhart said. “We haven’t traditionally identified that as a major benefit, but it’s definitely added.”

Monteilh said about 95 percent of tower locations have been determined to date. His company and the Coast Guard are working together with landowners and other stakeholders to identify the remaining sites and secure permission.

Each tower contains six radios — one tuned to VHF channel 16, the international calling and distress channel, four to region-specific channels determined by the Coast Guard, and one UHF radio used for communications with the Department of Homeland Security and other federal, state and local agencies.

All five VHF radios can transmit and receive simultaneously, covering up to 20 nautical miles offshore. The system also ties into telephone networks, enabling radio-to-phone calls with emergency first responders and hospitals, and offers digital recording of distress calls for instant playback and archiving.

In addition to the towers, Coast Guard command centers in each sector are being upgraded.

Tower-monitoring under Rescue 21 is not dependent upon physical proximity, which means that in the event of natural disasters like hurricanes, command center crew can be moved to a safe location in another sector and monitor their coverage area from there.

“This happened recently in New Orleans,” Monteilh said. “We moved the physical watch-standers to West Virginia, where there was no hurricane, and they monitored the New Orleans system from West Virginia.”

Mobile hardware can also be brought in during disasters or other emergencies, preventing any lapse in coverage.

Currently Rescue 21 is operational on most of the Atlantic and Gulf coasts, and much of the Pacific Coast. Southern California and the Great Lakes are the next areas scheduled to come online. Full system installation is expected to be completed by 2012, with the Alaska and western rivers system online by 2017.

In all, Rescue 21 is expected to cost just over $1 billion.

By Professional Mariner Staff