Flag O (Oscar)
ICS · O code word: Oscar pronounced: OSS-CAH Morse: −−−
In short: Man overboard.
Single-letter meaning (Pub 102)
Man overboard.
Morse sign
−−−
Dot = short sound, dash = long (three times longer). Hear it in the Morse translator.
In plain English
A yellow and red flag (diagonal). Someone has fallen overboard: everyone nearby should watch the water and help.
Where you will really see it
Hoisted immediately after a man overboard; in parallel the ship raises the alarm and works the radio (the urgency signal Pan Pan or Mayday, depending on the situation).
Common mix-up
O does not call for medical help (that is W). O means: there is a person in the water.
Keep going
- All signal flags: the search box and the full grid.
- Interactive mast: build your own hoist.
- Single-letter signals cheat sheet A to Z on one page.
The single-letter meanings are quoted 1:1 from Pub 102 International Code of Signals (NGA, public domain); the plain-English explanations are our own. Flag graphics: signal-flag-images (Unlicense).