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USCG Exam Practice · Light List, ranges, and light characteristics

A mariner observes a light that shows three flashes in a group, then a period of darkness, then repeats. This light is charted as which characteristic?

  1. AFl(4)
  2. BIso
  3. CFl(3)✓ correct
  4. DFFl

Why C is correct

Group Flashing — 3, charted as Fl(3), produces three flashes per group at a fixed period. Fl(4) would produce four flashes per group. Iso has equal light and dark periods with no grouping. FFl is a fixed light with a single superimposed brighter flash.

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A mariner observes a light that shows three flashes in a group, the… — USCG Exam Practice · CaptainsGround