Observe and identify
Developing level, about 2 min. IALA worldwide marks.
The situation
A navigation light lies ahead. Start playback and watch at least one complete cycle. Its period is an illustrative charted example; identify the combination of colour and rhythm.
Which mark matches the light you observe?
- West cardinal
- North cardinal
- East cardinal
Answers and explanations
Lookout: Cones point together around the middle black band. West is nine o'clock: nine quick flashes.
The sound answer
West cardinal
Yellow–black–yellow, with cone points together. Groups of nine quick or very quick white flashes. Pass west of the mark, using the chart to determine the danger extent.
Why the other options fall short
North cardinal
Black above yellow, with two cones pointing up. White continuous quick or very quick flashes. The named northern side is the indicated side for passage; check the chart for the danger and clearance. Here the observed cue identifies west cardinal. Yellow–black–yellow, with cone points together. Groups of nine quick or very quick white flashes. Pass west of the mark, using the chart to determine the danger extent.
East cardinal
Black–yellow–black, with two cones pointing apart. White light in groups of three quick or very quick flashes. Pass on the eastern side and establish clearance from the chart. Here the observed cue identifies west cardinal. Yellow–black–yellow, with cone points together. Groups of nine quick or very quick white flashes. Pass west of the mark, using the chart to determine the danger extent.
Cardinal marks
Yellow–black–yellow, with cone points together. Groups of nine quick or very quick white flashes. Pass west of the mark, using the chart to determine the danger extent.