International Code of Signals – Nautical flag used by ships at sea and the U.S. Navy. The flag is described as having a swallowtail “V” shape with a vertical separation of white and blue contrasting colors. The flag represents the letter A or phonetic Alpha (The International Code of Signals refers to it as “alfa“).
Diver Down Flag Meaning
A – ALPHA (alfa – ICS), Diver Down
“I have a diver down near my location; keep clear at slow speed.” (when stationary)