serious confusion at sea. Sound signaling in fog
should, therefore, be reduced to a minimum. Signals
other than the single-letter signals should be used only
in extreme emergency and never in frequented
The signals should be made slowly and clearly.
They may be repeated, if necessary, but at sufficiently
long intervals to ensure that no confusion can arise and
that one-letter signals cannot be mistaken for
Under international procedures, a transmitting
ship calls in the same manner as by flashing light;
the receiving ship replies with the answering sign.
(No call or answer is sent, however, when trans-
mitting single-letter signals.) The transmitting ship
then sends the entire message. Unless the receiving
ship misses a word or group, it does not answer until
the ending AR is made; it then indicates receipt by
If the receiving ship misses a word or group
during the transmission, it immediately signals RPT
to indicate the omission; the transmitting ship goes
back a few words or groups, then continues the
message. Ships do not exchange identities in this
form of communication despite use of the general
When using the International Code of Signals
in cases of language difficulties, the principles of the
Radio Regulations of the International Telecom-
munications Union then in force have to be
observed. Letters and figures are spelled out
according to phonetic spelling tables. When coast
and ship stations are called, the identity signals or
names shall be used.
The call consists of the call sign or name of the
station called, the group DE, and the call sign or name
of the calling station.
Difficult names of stations should be spelled.
After contact has been established, the call sign or
name need not be sent again.
The reply to a call consists of the call sign of the
calling station, the group DE, and the call sign or name
of the station called.
When calling all stations in the vicinity, the group
CQ is used.
To indicate that groups are from the International
Code of Signals, the word INTERCO is inserted. The
group YZ will be used when plain language is used in
The signal AS is used when the station called is
unable to receive traffic immediately.
To receipt for a transmission, the signal R is used.
Repetitions are obtained by RPT followed by
prowords if needed.
To end a transmission, the signal AR is used.
MORSE SIGNALING BY HAND
FLAGS OR ARMS
A station that desires to communicate with
another station by Morse signaling using hand flags or
arms may indicate the requirement by transmitting to
that station the signal K1 by any method. The call
signal AA may be made instead.
On receipt of the call, the station addressed should
make the answering signal or, if unable to
communicate by this means, should reply with the
signal YS1 by any available method.
The call signal AA AA AA and the signal T should
be used, respectively, by the transmitting station and
the addressed station.
Normally both arms should be used for this
method of transmission, but in cases where this is
difficult or impossible, one arm can be used.
All signals will end with the ending signal AR.
Figure 6-1 shows positions for Morse signaling by
hand flags or arms.
International single-letter signals, which may be
made by any method of signaling, have specific
meanings that in most cases do not parallel the same