USCG Exam Practice · Light List, ranges, and light characteristics
A mariner observing a light notes that it appears to be continuously lit but is periodically extinguished for brief intervals, and the total time the light is visible is greater than the total time it is eclipsed over each full period. A second light in the same area shows a single brief flash per period, with the dark interval clearly longer than the flash. Which pair of designations, in the same order, correctly identifies these two lights?
- AFl for the first light; Oc for the second light
- BOc for the first light; Fl for the second light✓ correct
- CIso for the first light; FFl for the second light
- DFFl for the first light; Fl(3) for the second light
Why B is correct
The first light — continuously lit with brief eclipses and light duration exceeding dark duration — matches Occulting (Oc). The second light — a single brief flash with dark period longer than the flash — matches Flashing (Fl). The Light List explicitly states Occulting is the opposite of Flashing, and Flashing has a duration of light shorter than the duration of darkness.
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