What colour are apron edge lights used to delineate the boundary of the apron?

Apron edge lights are essential for safety and operational clarity on the airside of an airport. They are specifically designed to delineate the boundary of the apron area. The correct answer is blue because blue lights indicate the transition between the apron and other areas, such as taxiways or runways. This helps guide pilots and vehicle operators by visually establishing the limits of the apron.

The use of blue lights is consistent with aviation standards that aim to prevent incursions and enhance situational awareness. This is particularly important during low visibility conditions or nighttime operations when distinguishing between different areas on the airfield can be challenging. By ensuring that the apron edge is marked with blue lights, it provides an effective visual cue to all users of the airside environment.