Code Flag Alpha (A)
An International Code of Signals flag meaning “I have a diver down; keep well clear at slow speed” when flown alone.
Code flag Alpha is vertically divided white and blue, with a swallow-tailed blue fly. A vessel engaged in diving operations displays it where it can best be seen when the flag is an appropriate signal under the applicable rules.
The flag does not create a fixed universal exclusion distance or remove the need for the lights and shapes required by the collision regulations. Other vessels should proceed cautiously, keep a safe distance and comply with local diving rules.
