The International Code of Signals assigns each letter A–Z a distinct maritime flag with its own single-flag meaning — Alfa for 'diver down', Bravo for 'dangerous cargo'. Ships still fly them for legal signalling and naval ceremony.
Flags A-Z
A
Alpha
Diver down — keep clear and slow speed
B
Bravo
Dangerous cargo — loading/unloading explosives
C
Charlie
Yes / Affirmative
D
Delta
Keep clear — manoeuvring with difficulty
E
Echo
Altering course to starboard
F
Foxtrot
Disabled — communicate with me
G
Golf
Pilot required / I require a pilot
H
Hotel
Pilot on board
I
India
Altering course to port
J
Juliett
Fire on board — keep clear
K
Kilo
I wish to communicate with you
L
Lima
You should stop your vessel immediately
M
Mike
My vessel is stopped — making no way
N
November
No / Negative
O
Oscar
Man overboard
P
Papa
In port: about to sail
Q
Quebec
My vessel is healthy — request clearance
R
Romeo
Used in combinations only
S
Sierra
My engines are going astern
T
Tango
Keep clear — engaged in trawling
U
Uniform
You are running into danger
V
Victor
I require assistance
W
Whiskey
I require medical assistance
X
X-Ray
Stop your intention — watch for signals
Y
Yankee
I am dragging my anchor
Z
Zulu
I require a tug
Special Signals
NC together
International distress signal
Hoist November and Charlie together
Oscar alone
Man overboard
Most urgent single-flag signal
Alpha alone
Diver down — keep clear
Keep clear and slow speed
Bravo alone
Dangerous cargo
Explosives loading/unloading
Quebec alone
Request customs clearance
Yellow flag — request to enter port
How to Use
Single flag signals have specific meanings at sea — hoisting Flag A means I have a diver down, keep clear.
NC hoisted together (November + Charlie) = International distress signal.
Oscar alone = Man overboard — the most urgent single-flag signal at sea.
NC hoisted together (November + Charlie) = International distress signal.
Oscar alone = Man overboard — the most urgent single-flag signal at sea.