Where no barrettes are used, each centre line light position of a category I precision approach lighting system shall consist of:
A single light source
A capacitor discharge light
A single light source in the innermost 300 m, two light sources in the central 300 m and three light sources in the outer 300 m
A single light source in the outer 300 m, two light sources in the central 300 m and three light sources in the innermost 300 m