Trouble ashore? Call 911 and tell the operator where to send help. Even if you can’t verbally tell an operator your location, chances are that “Enhanced 911” will do it for you. Using GPS or data from a wireless network, the system automatically associates a physical address with the calling party’s telephone number and routes the call to the most appropriate public safety answering point for that address. The caller’s address and information is displayed to the call-taker immediately upon call arrival, providing emergency responders with the location of the emergency without the person calling for help having to provide it.

Trouble afloat? Call “Mayday” on VHF radio Channel 16 and tell the U.S. Coast Guard (USCG) where to send help. But what if you don’t know your exact location or don’t have time to report it? Finding individuals in distress on the water is usually much harder than finding them on land. Until recently, mariners making Channel 16 distress calls could only give their position verbally, but with the advent of Rescue 21, information on their position can be determined more accurately than ever before.

Rescue 21 (R21) is an advanced command, control, and communications system created to better locate mariners in distress and save lives and property at sea and on navigable rivers. As of June 2010, the system is up and running in 26 Coast Guard sectors, covering 36,985 miles of U.S. coastline that includes the entire eastern seaboard, the Gulf Coast, and much of the West Coast.

In August, the Coast Guard hosted a Rescue 21 acceptance ceremony in Sector Baltimore. During the ceremony, U.S. Rep. Elijah E. Cummings, D-Md., who serves as chairman of the House Transportation and Infrastructure Committee’s Subcommittee on the Coast Guard and Maritime Transportation, remarked: “… Somebody got up this morning somewhere in America and doesn’t know that Rescue 21 is going to save their life. Perhaps there’s someone in a boat right now who doesn’t realize that in six months, it’s going to be Rescue 21, which is going to save their life. …”

Cummings is right. To date, R21 has been used in more than 21,270 search and rescue cases and helped the Service save lives and property. Its communications and direction-finding capability have proven invaluable in helping the USCG find and respond to mariners in distress in a timely fashion, Rescue 21 Program Manager Gene Lockhart said.

“The direction-finding, the greater clarity of the [distress] calls, all of these add up to us being able to locate and isolate the call to a specific area and send our assets there more quickly.”

R21 is based on a system of VHF-FM radio towers located along America’s shorelines that were erected as part of the National Distress and Response (NDRS) System in the 1970s. The NDRS towers received and transmitted voice and some data signals and provided limited direction-finding capability. In September 2002, the Coast Guard awarded General Dynamics a contract (now valued at approximately $730 million) to fully implement an enhanced distress system called Rescue 21 that would employ the latest in radio, computer processing, and software technology.

As part of Rescue 21, the number of radio towers has grown and they now connect with dedicated R21 workstations/consoles and operators at about 270 USCG facilities nationwide. The system provides better communication and interoperability in emergency situations and provides communications coverage out to a minimum of 20 nautical miles off the coastal zone.

Rescue 21 builds on its communication effectiveness with the ability to receive Digital Selective Calling (DSC) distress alerts. DSC alerts are automatically formatted digital data messages that include the name and description of the vessel and its location if its VHF radio is integrated with GPS. All a mariner need do is press and hold the red “distress” button on a maritime VHF radio (nearly all maritime VHF transceivers currently on the market have this DSC feature) and the distress alert is sent over marine emergency channel 70 to the Coast Guard and any other DSC-equipped boats within range.

The DSC alert shows up as a text message to a USCG operations specialist at a Rescue 21 workstation. If the vessel has registered its VHF radio’s maritime mobile service ID (MMSI) and integrated the radio with a GPS, the text message will include the vessel’s latitude and longitude position, the vessel’s characteristics, and the owner’s identity and contact information.

A DSC alert received by R21 can dramatically reduce the time needed to render assistance by taking the search out of search and rescue. That’s why the USCG stresses that mariners always have a good quality VHF radio.

“At a minimum, boaters should have a good quality VHF marine radio,” Lockhart said. “When the equipment is properly integrated, it allows for the inclusion of the position along with the basic distress call and ID information. That greatly facilitates reducing the Coast Guard’s response time.”

But Rescue 21 can reduce response time even in cases where no GPS position information is sent by those in peril.

“With our new direction-finding capability, which is also a very critical piece of Rescue 21, we can pick up lines of bearing over the VHF calls,” Lockhart said. “That helps us narrow our search. Even if we have just a single line of bearing, we can send a response asset along that line and employing traditional techniques, they can significantly reduce our search time. With two or more lines of bearing [the search] gets fairly precise.”

Unlike its NDRS predecessor, Rescue 21 can draw a line between the tower and the source of the transmission. As in the old system, areas where the lines cross would then be searched, but it’s a significantly smaller area. An important side benefit is that the improved accuracy also helps identify hoax calls or accidental calls generated from boats that are sitting on land. Rescue 21 also can be used to record calls, Lockhart explained.

“When the system captures a call, we have a play back capability that allows an operator to immediately play back the last few seconds so that they more accurately interpret what they heard if they didn’t pick it up the first time.”

The playback capability can be invaluable if, for example, a boater in distress can only make one verbal position report and the transmission or the caller is at first unclear. Additional phone lines can also be patched into the system, very helpful in instances where the Coast Guard may need to call up a translator or doctor to speak with a boater using a radio. The translator can be patched directly into the radio system, eliminating the need for a Rescue 21 operator to serve as a middleman. R21 not only provides better location and communication capability, but the information provided can also allow USCG to dispatch the right mix of assets, whether they be surface, aviation, or a combination of both.

To demonstrate, Lockhart describes a typical distress scenario, say 15 miles offshore, facilitated by R21.

“The system will pick the distress call up and in a very high number of cases we pick up the call the first time. Because we have some overlapping coverage in the majority of our [sectors], it’s not uncommon for us to pick that call up from two towers and sometimes more depending on weather and other factors. R21 will pick the call up and immediately the direction-finding system will acknowledge the call and put a line of bearing over the direction from which it originates.

“When it does, that gets the [USCG] operator’s attention, the operator responds and immediately tries to contact the distress party, asks the nature of the emergency, begins to get additional information if they still have contact, and work out a response solution. We’ve had a few cases over the last couple years wherein we get only one call. If the vessel is on fire or rapidly taking on water, we may only get one call before they abandon the vessel. You may also have a scenario in which there wasn’t time to even make a call but they managed to push the red DSC button on the radio, sending an alert out.”

A real-world emergency played out in May 2010 when multiple Coast Guard units from Group Humboldt Bay (Sector San Francisco) responded to a mayday call from the F/V Sea Clipper at 8:42 p.m. The vessel was fishing 13 miles off of Humboldt Bay when it suddenly rolled over and started flooding.

“The boat very quickly rolled 90 degrees and stayed there,” Lockhart explained. “The skipper quickly got off a distress message. Because he had all the right [emergency] gear properly integrated and registered, we put two lines of bearing over the vessel and we were able to dispatch an aviation and surface asset [to the scene].

Indeed, the Coast Guard’s report records that the master of Sea Clipper sent a terse Channel 16 transmission, saying, “MAYDAY, MAYDAY! Going over! 40.48N 124.32W!” Immediately after the position was passed, the radio went silent.

Using Rescue 21, the Coast Guard’s communications center in McKinleyville was able to replay the initial mayday call and decipher the almost unintelligible latitude and longitude broadcast during the desperate transmission. The direction-finding capabilities of the Rescue 21 system were also able to allow the watch standers to verify that the position received during the mayday call was accurate. The Coast Guard immediately issued an urgent marine information broadcast to alert other mariners to the distress. The fishing vessel Pacific Ram was near the position given during the call and headed for the scene. Also responding was the towing vessel Lion, south of the position given.

The CGC Dorado, homeported in Crescent City, Calif., was at anchor in Trinidad Bay and was under way minutes after receiving the call. An Air Station Humboldt Bay MH-65C Dolphin helicopter was launched and a 47-foot Motor Lifeboat was dispatched from Station Humboldt Bay.

With only a frenzied mayday call to go on, and with all radio calls responding to the mayday going unanswered, USCG units responded for a worst-case scenario. Nine minutes after the initial broadcast, Sea Clipper was able to make another radio broadcast. The fishing vessel confirmed that it was they who had made the initial mayday broadcast. Sea Clipper’s skipper said that he thought some of their fishing gear had snagged on the bottom of the sea floor and caused the boat to rapidly roll 90 degrees with little warning. The master only had time to issue the quick mayday before the crew raced to cut away the gear that had apparently gotten caught below the surface. The vessel had taken on water when it rolled and the bilge and engine room were flooded.

The Dolphin arrived overhead shortly thereafter and orbited the fishing vessel while the motor lifeboat and Pacific Ram came up alongside the Sea Clipper to render assistance. The Dorado then arrived and assumed escort duties. After transferring dewatering pumps to the vessel, Sea Clipper was righted and escorted to Humboldt Bay and its mooring at Woodley Island with all aboard safe and sound.

“It’s a remarkable thing to see,” Lockhart said. “It really does show that this direction-finding capability and the operator’s ability to look at those lines of bearing are pretty accurate. We spend a good bit of time ensuring that the system we install is tuned up and calibrated prior to turning it on.”

The Coast Guard and the contractor also continually assess and add updates to the system as advancements in the commercial technology are made. And the service keeps one eye continually on system security, performing updates on a monthly basis. Keeping Rescue 21 viable as America’s Maritime 9-1-1 and as a vital command and control system requires nothing less.

“We have a dedicated effort to ensure that the system is up and running,” Lockhart concluded. “Rescue 21 doesn’t just support the search and rescue mission, which is its prime mission. It supports all Coast Guard missions.”

This article first appeared in the Coast Guard Outlook 2011 Edition.