Distress flares are vital to boating safety, but pyrotechnic flares can pose a safety hazard to people not trained in their use. In addition, expired flares can create environmental hazards through leaching chemicals when disposed of in landfills or at sea. As an alternative, the Coast Guard has been researching the suitability of light emitting diode (LED) devices as effective distress signals through its Research, Development, Test and Evaluation Program.
The Coast Guard offices of Search and Rescue, Auxiliary and Boating Safety, and Design and Engineering Standards, Lifesaving and Fire Safety Division (CG-ENG-4) recognized that pyrotechnic distress signals are old technology. Existing distress signal requirements and electric distress signal specifications as set forth in the Code of Federal Regulations need to be revised to match the advanced technology and performance capabilities of newer devices, said Martin Jackson, a staff engineer with CG-ENG-4.
The Coast Guard Research and Development Center (RDC) in New London, Connecticut, initiated a multi-year project to develop a signal characteristic that could be used as an alternative to a pyrotechnic signal.
“The advancement of Coast Guard missions to enhance maritime safety, protect the environment, and provide better electronic visual distress signal devices for recreational boaters that are safer to use for search and rescue and allow easy recycling of batteries were the drivers for this project,” Jackson said. “RDC was the one place with the necessary expertise to assess the field of signal devices; test alternative signals; establish the critical characteristics that enhance visual detection, particularly for the recreational boater; and increase the probability of rescue in a distress situation.”
The project initially emphasized finding the right combination of conspicuous, nighttime, visual characteristics that could meet or exceed that of traditional signals. After a series of laboratory and field vision-research tests that included many colors and flash patterns, the project team recommended a group-flash, alternating cyan and red-orange color, 4 hertz characteristic.
“It was interesting to learn that at six miles, most observers thought a red flare looked like a vessel sidelight, while they easily identified the cyan and red-orange characteristic,” said project manager M.J. Lewandowski, who works in the Environment and Waterways Branch at RDC.
However, Coast Guard aviation representatives pointed out that the ideal visual signal might not be good for searchers using night-vision imaging systems with “minus-blue” filtering. An additional field test developed a near-infrared component to the characteristic, allowing full night-vision imaging system detectability.
During the RDC research project, the Office of Design and Engineering Standards requested the Radio Technical Commission for Maritime Services (RTCM) institute a special committee to develop a “standard” that incorporates the new signal characteristic into a producible device. Once manufactured, such a device could act as a substitute for pyrotechnic flare carriage requirements on recreational vessels.
Manufacturers had concerns about LED cost and power use, which led to more testing in 2017. Though results were similar to beforehand, observer test-results indicated that a red-orange/cyan, quick-flashing SOS pattern might be more identifiable as a distress signal.