Factors Influencing the Performance of Visual Distress Signals

John D Bullough PhD FIES
Lighting Research Center
Rensselaer Polytechnic Institute
Email bulloj@rpi.edu



The present paper summarizes efforts undertaken to review the performance characteristics of visual
distress signals using light emitting diodes that might replace pyrotechnic-based flare distress signals
in the future. Field photometric measurements were made on board a rescue vessel and near the
shore at a coastal station to ascertain typical visual environments under which visual distress signals
might be viewed, and to understand the visual tasks associated with searching for and detecting
these signals. With this information in mind, the literature was systematically reviewed to identify the
factors that are likely to influence the performance of visual distress signals, and to provide
preliminary guidance regarding the design of visual distress signals constructed with lighting emitting

KEY WORDS: Visibility, Color vision, Effective intensity, Visual search

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