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Light Emitting Diodes (LEDs) have the potential to replace incandescent bulbs currently used in aircraft anti-collision lighting. LEDs require less power to operate, and possess the ability to flash without the addition of moving parts. Compared to incandescent bulbs, however, LEDs yield a slightly different spectral output and a different intensity profile when flashing. The impact of these differences on the viewer’s ability to detect the light was examined to determine if LEDs can successfully replace incandescent bulbs on aircrafts and runways. Using an automated system to drive an LED with variable intensity and duration, the light source was displayed to naïve participants to establish visibility thresholds for solid and pulsed LEDs. Participants were asked to immediately respond as to indicate if a light was present. The data collected were examined and applied to the different models currently available for determining the effective intensity of a pulsed light.