ICS signal flags quiz
The International Code of Signals (ICS / ICOS) uses 26 alphabet flags (A–Z), 10 numeral pendants, and 4 substitute flags. Single-letter signals have specific urgent or important meanings under the ICS — for example, Flag O means man overboard and Flag Q means the vessel is requesting free pratique.
Two quiz modes: identify the letter for a given flag, or identify the single-letter meaning. Use this for STCW oral-exam revision or watchkeeping refresher.
Score
0 / 0
Which letter is this flag?
When to use this tool
STCW oral-exam revision, GMDSS operator refresher, bridge-team novel-signal recognition. Also used during pilot boardings + Suez Canal transits where flag hoists still supplement VHF.
Regulatory basis
International Code of Signals (ICS), published by IMO. Successor to the 1969 revision. Alphabet flags (A-Z), numeral pendants (0-9), substitute flags (3), + Code/Answer pendant. Single-letter urgent signals (e.g. B = dangerous cargo, H = pilot on board, O = man overboard, Q = free pratique requested).