Evaluation of L-866 Obstruction Beacon

This report describes and documents the results of flight testing and evaluation of various strobe lighting systems
(L-866) for possible use in identifying short skeletal towers of 500 feet or less during daylight conditions. Use of such lights for obstruction marking of towers might prove more economical than the current technique of painting for daytime identification and provide improved hazard warning..

Approximately 450 flight approaches were made to a 492-foot tall skeletal tower by subject pilots to determine whether they could first acquire the strobes provided, or the paint, or the tower structure itself. Many variables were considered including number of strobes, strobe aiming angles, types of weather, approach direct ions (upsun, downsun or sidesun), and descending approaches. Most of the evaluation was accomplished during the daytime, with a limited amount of testing at night. A requirement to test during low visibility conditions was satisfied by use of newly developed variable density goggles for the majority of the flights. It was concluded that, except for downsun conditions, the 20,000 candela strobe lighting system is more effective than paint for marking short skeletal towers of 500 feet or less. With respect to downsun conditions, strobe lighting is more effective up to 1 mile from the tower and essentially equally as effective between 1 and 2 miles; greater than 2 miles, painting is more effective. The concept of utilizing the L-866 strobe lighting system In place of painted tower markings appears operationally beneficial.

Author: Bret B. Castle