Airborne Evaluation of Retro-Reflective Beads

Retro-reflective beads are designed to redirect and return light back to its source. The inclusion of retro-reflective beads in painted surface markings can increase their conspicuity. It has been suggested that Type III retro-reflective beads, which have a higher index of refraction (IOR) compared to Type I beads, will substantially increase the conspicuity of paint markings and could help prevent runway incursions. The FAA uses Federal Specification TT-B-1325D, “Beads (Glass Spheres) Retro-Reflective,” to specify retro-reflective beads.

The majority of the test subjects involved in the tests at both ACY and SAV stated they do not use runway markings as a visual cue on approach to a runway at night. They focus on the runway lights. Of the subjects participating, all but one reported no difference in ease of detection between Type I and Type III bead markings.

DOT/FAA/AR-TN10/8
Author: Anthony J. Previti*, Holly Cyrus, and Donald W. Gallagher