EVALUATION OF ILS CHECK LIGHT SYSTEM.

An optical system for flight checking the Instrument Landing System ILS was evaluated at the National Aviation Facilities Experimental Center in order to determine the utility of such a system as a source of position information during ILS flight checks. Two beams of light were projected. The top edge of one beam was aligned with the ILS glide slope the right edge of the other beam was aligned with the runway centerline. A flight check aircraft was navigated along these paths by visual reference to the light source. The accuracy with which an observer in the aircraft could identify the centerline and glide path by observing the check light was determined. Although the ILS Check Light System performed in accordance with the original design requirements, it was determined that this system was unsuitable in meeting the new ILS flight check requirements and it was recommended that the system not be adopted for operational use.