What determines the distance between each set of marking lights (the distance between each TDP)?

• A. Wind speed
• B. Time of day
• C. The size of the aircraft
• D. Pilot preference

Answer: (C)

The spacing of marking lights is scaled to match the size of the aircraft that will land. Larger aircraft have longer touchdown footprints, so the lights are spaced farther apart to give the pilot proportional visual cues that help judge distance and alignment to the touchdown point. Smaller aircraft need shorter cues, so the lights can be spaced more closely to provide accurate reference within a shorter landing area. Wind speed or time of day mainly affect approach conditions and visibility but not how the lights are spaced. Pilot preference can influence handling or briefing, but the standard spacing is set by aircraft size to ensure consistent, safe guidance.