Anonymous distress messages hamstring Coast Guard

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A VHF DSC radio, like this Furuno FM4000, has a DSC “distress” button for sending an automated distress message. Some mariners are sending distress calls without a GPS  position or MMSI number attached.

When the VHF DSC radio system was first developed, the idea of automated distress calls seemed an idea with only upside. What could be better than a system that ensured a call for help got sent and received, even if you were too busy trying to save your boat to do more than push a button? Unfortunately, the law of unintended consequences has kicked in. Many of the automated distress calls the Coast Guard is receiving have no lat/long position or Maritime Mobile Service Identity (MMSI) number associated with them. Leaving Coast Guard watchstanders with no way of contacting the vessel sending the call.

Coast Guard Rear Admiral R.E. Day outlined the problem in a recent letter to National Marine Electronics Association president David Hayden, “Of the roughly 100 digital selective calling (DSC) distress alerts we are now receiving each month, approximately nine out of 10 do not have position information (i.e., do not have a GPS receiver interconnected to their DSC-equipped VHF radio), and approximately six out of 10 have not registered their Maritime Mobile Service Identity.” The result is frustration for Coast Guard personnel, “…there’s little … a watchstander can do after receiving a distress alert with no position information, using an unregistered MMSI, and having no follow up communications.” Regular Ocean Navigator contributor John Kettlewell describes the resulting confused and annoying chatter on the radio due to this problem:
“The DSC false alarms get so bad on some weekends in southern New England that I turn off the VHF radio if someone is trying to nap. I don’t believe I’ve ever heard any actual distress alert on the DSC — they all seem to be false alarms. Also, there is lots of wasted air time with the Coast Guard calling all around every few minutes trying to figure out who and where the alarm is coming from.”

If you think about, this problem rarely occurred before automatic distress calling. In the days before DSC, mariners calling “Mayday” on channel 16 were usually highly motivated to stay on the air and talk to any Coast Guard radio operator who responded. Now, however, after pushing the automated distress button, it appears that mariners leave the radio to deal with other pressing issues, or are pushing the distress button by mistake or think there is no effect when the button is pushed.

According to Joe Hersey, chief of Spectrum Management and Telecommunications Policy Division at Coast Guard headquarters in Washington, D.C., the USCG would love to know more about why mariners are sending these false or incomplete distress calls. “We don’t really have the data showing why the problem is (happening) with mariners,” Hersey wrote in an e-mail, “but we have some ideas.”

The first reason is simply a lack of knowledge by mariners about the problem. In fact, only a few years ago, the Coast Guard told mariners that it had no mechanism for receiving automated distress calls via DSC. Hence, pushing the distress button didn’t register on the Coast Guard VHF network. However, with the deployment of the Coast Guard’s Rescue 21 system, which updates the Coast Guard VHF communications network to operate with DSC, that situation has changed and now Coast Guard watchstanders are receiving these distress messages. The letter from Admiral Day to the NMEA is clearly part of an effort to get the word out to boaters that the VHF DSC radio’s distress button should not be pushed unless there is a bona fide emergency.

Another reason might be the lack of a “test” function on early VHF DSC radios. “When DSC was first developed, the international regulators prevented a test function from being included under the assumption that one could always test it by calling a VHF public coast station,” Hersey explained. “Ten years ago, when the regulators realized there were no public coast stations left, they allowed the test function to be specified and mandated. It took that long for radios to show up with that feature.” According to Hersey, effective this past March, radios must now have that capability. The Rescue 21 system is set up to correctly identify test messages. But, of course, older radios do not have a test capability.

The final reason for the problem is the lack of connection by many radios to the boat’s GPS system. This is partly because, as Hersey wrote, “…interconnecting a GPS and VHF radio on a recreational boat is a lot more difficult than we envisioned it would be.” Plus, many boaters are reluctant to permanently connect their radio and GPS because they remove their radios from their boat to prevent theft.

Mariners should take steps to correct this problem so they have a VHF DSC distress system that works when needed.

GPS interference?
Lately a coalition of GPS companies and user groups called Coalition to Save Our GPS (CSOG) has formed to protect GPS signals from the possibility of interference from a wireless Internet access firm called LightSquared. The wireless firm has plans to deploy a reported 40,000 ground stations that will transmit on a frequency adjacent to that used by GPS. According to CSOG, the LightSquared signals will be “one billion times more powerful than GPS signals as received on Earth.”

The fear for marine GPS users is that the LightSquared service will interfere with GPS signals in harbor or coastal situations. Offshore, there will be no LightSquared stations within range. But it’s the harbor and coastal situations where you want the best GPS coverage since that’s where the hard stuff tends to be located.

Some members of CSOG include: Garmin, Trimble, the International Air Transport Association, the Aircraft Owners and Pilots Association, Caterpillar Diesel, and a host more.

CSOG states emphatically that the LightSquared system represents a great potential danger to GPS, but so far, this conclusion is based on preliminary lab testing. More real world testing is clearly needed before the LightSquared system should be allowed to go forward. That seems prudent to avoid the possibility of 40,000 coverage holes, one of which just may include your harbor or favorite stretch of coast.