What lighting system consists of two parallel light rays used to direct the receiver pilot to the optimum contact position?

The Pilot Director Lights (PDL) system consists of two parallel light rays that guide the receiver pilot to the optimum contact position during aerial refueling or other similar operations. This system is designed to provide visual guidance, indicating the correct path for the pilot to follow as they maneuver into position.

The PDL delivers clear and straightforward cues that help improve situational awareness and precision during critical moments, enhancing safety and efficiency in the operation. By utilizing the parallel light rays, the system allows pilots to judge their alignment relative to the refueling aircraft or other pertinent targets, facilitating a smooth and accurate approach.

Other systems listed, such as Glide Slope Indicators or Visual Approach Slope Indicators, primarily focus on providing glide path information for landing approaches rather than direct lateral guidance, which differentiates their function from that of the PDL. Runway Threshold Lights primarily signal the end of the runway and do not offer the same operational guidance as the PDL.