Evaluation of L-804 Elevated Runway Guard Light Fixtures

The number of inadvertent runway incursions has grown during recent years, increasing the importance of protective visual guidance systems for incursion prevention. One such visual system is the L-804 elevated runway guard light fixture. Also known as a wig-wag light, these fixtures contain two alternately flashing yellow lights and are used to help identify runway holding positions to pilots. Pilots, however, have indicated that the light intensity (600 candelas minimum average intensity) and flash rate (average of 35 flashes per minute per lamp) of the L-804s are inadequate.

The L-804s were examined under day and night visual flight rules (VFR) and instrument flight rules· (IFR) conditions from various distances and angles. . Particular attention was paid to performance characteristics such as intensity , flash rate, vertical and horizontal aiming angle, lamp separation, and the usefulness of providing a hood over each lamp.

As a result of the evaluation it was determined that the L-804 specifications needed to be modified. Flash rate should be increased to 45 to 50 flashes per minute per lamp. The light intensity of the Mode 1 (constant current) L-804 when energized at 6.6 amps and tested with one lamp in the steady burning mode and the other lamp masked out should be 4100 candelas. The light intensity of the Mode 2 (constant voltage)L-804 when energized at 120 volts and similarly tested should be 940 candelas.