DSC: The red button that saves lives

In reference to the term red button, it’s historically been seen as a symbol of danger. However, in Coast Guard search and rescue cases, it can mean the difference between life and death for troubled mariners.

Petty Officer 3rd Class Jacob Gunderson communicates via VHF-FM radio systems while conducting boating operations.

Boaters who find themselves in trouble in Alaska may not have time to report their location by a call on the radio. A VHF-FM marine-band radio on board with Digital Selective Calling allows for a digital transfer between radios versus voice transmission, which allows mariners to instantly send an automatically formatted distress alert to the Coast Guard. All a boater has to do is push the red button labeled distress on the right-hand side of the radio.

In 1999, the Federal Communications Commission required that all new maritime radios be equipped with DSC. DSC uses digital data to increase the range of its signal and provides an automatically formatted distress alert to rescuers. Each radio equipped with a DSC has a unique number called a Mobile Maritime Service Identity, or an MMSI number. The vessel’s VHF radio must be registered for an MMSI number through Boat US.

As an emergency occurs and the distress button on the radio is pressed, a vessel’s information is broadcasted to the Coast Guard as well as to all vessels equipped with DSC within range. Also, if a DSC radio is connected to a GPS, that vessel’s location will be broadcasted as well. As a result, it is highly encouraged that the DSC radio be connected to the vessel’s GPS in order to send an accurate position to assist emergency responders in responding to the distress.

“However, DO NOT press the distress button to test the system,” said Chief Petty Officer David E. Bergman, a command duty officer at Coast Guard Sector Anchorage. “Instead, use the MMSI number of a friend or a local shore station. Enter their MMSI number into the radio as if you were using a phone. Then, choose a working channel, not channel 16.”

In non-emergency situations, boaters with DSC radios can hail one another directly by punching in the nine-digit MMSI number of the vessel they wish to hail. DSC minimizes the time necessary to establish communications and clears much of the chatter typically heard on channel 16. Additionally, it gives precedence to distress calls.

“A DSC-equipped VHF radio onboard is a lifeline to nearby boaters,” said Bergman. “The DSC allows a distress signal to be relayed to the closest available vessel, which increases the chances that the call for help will be heard. It is one of the most important radio systems a boater should have with them.”

All passenger and cargo ships are required to carry DSC-equipped radios. In June of 1997, the FCC adopted a Report and Order requiring radios accepted on or after June 17, 1999 to include DSC.

“It is crucial for mariners to have a DSC-equipped radio,” said Bergman. “Digital Selective Calling has the capability of taking the search out of search and rescue.”

Many modern VHF-FM radios are equipped with Digital Selective Calling (DSC). It is of utmost importance to note that the DSC radio must be properly registered with an MMSI number through Boat US and must be properly interfaced with the GPS in order to send an accurate position in the event of distress.