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All questions
Visual Aids

What does 'Fl(3) W 15s' mean on a chart?

Short answer

Group of 3 white flashes, period 15 seconds

Fl(3) W 15s = Group flashing (3 flashes per group), White colour, 15-second period (one complete cycle takes 15 seconds).

Quick check

What does 'Fl(3) W 15s' mean on a chart?