Call Signs
The following call signs are authorized for use in
calling and answering: visual, international, tactical,
task organization, collective, and indefinite. Address
groups may be used as call signs by Coast Guard
and Navy commands (except in non-military
communications.)
Call signs and address groups in message headings
will ordinarily be arranged in alphabetical order in the
form in which they are transmitted, whether plain,
encrypted, or mixed. For this purpose, / (slant sign)
and figures 0 through 9 will be considered the
twenty-seventh through thirty-seventh letters of the
alphabet. Care must be taken to avoid separating
groups of related call signs or conjunctive address
groups, which are interdependent.
The different methods of visual signaling require
variations in procedure for calling and answering. The
necessary instruction for each method is prescribed
throughout this chapter.
FLASHING LIGHT PROCEDURES
LEARNING OBJECTIVES: Explain the
procedure for calling, answering, relaying,
verifying, repeating, correcting, and receipting
using directional and non-directional flashing
light. Identify procedures for communicating
with aircraft, with daylight signaling lantern
(DSL), and infrared.
The two forms of flashing light used are
directional and non-directional. Directional procedure
is always employed when using a directional light. It
is also employed when using a non-directional light
when the call is that of a single station.
Non-directional procedure is one station transmitting
to a number of other stations simultaneously by means
of a light showing over a wide area. See appendix II
for tips for sending and receiving flashing light.
USE OF SIGNAL LIGHTS
In wartime, the greatest care is to be taken when
signaling at night. Flashing light is to be used only
when necessary and a minimum of light employed
except when making recognition signals. Then, a light
of sufficient brilliancy must be used to ensure its being
immediately seen. You must, however, always
remember that in heavy weather small ships have
trouble reading dim lights.
The background must always be considered, and
care should be taken not to use a signaling light close
to or in line with navigation lights. No upper-deck
lighting should be visible on or in the vicinity of the
signal deck.
The use of signal lights at dusk and dawn must be
avoided whenever possible. If, however, their use is
unavoidable, you must pay constant attention to the
brilliancy of their light.
At night, a constant watch is to be kept on the ship
of the OTC by all other ships. It may be found, after
communication has been established, that the
brilliancy of the light can still be further reduced. It is
absolutely essential when using any type of directional
light to keep it trained accurately throughout the
transmission of the message.
At all times, ships are to inform other ships
signaling to them when their lights are observed to
be brighter than necessary, by use of the prosign D.
Frequently test sight arrangements of lights for
alignment. To prevent masthead and yardarm
signaling lights from being accidently lighted, the
switch in the power supply line should be kept open
until use of the light is actually required.
DIRECTIONAL PROCEDURE
The transmitting station waits for the receiving
station to make a flash for each word, prosign, coded
group, or operating signal. Should the receiving
station fail to flash for the group, it will be repeated
by the transmitting station until a flash is received
from the receiving station. An exception to this rule is
that a flash is not necessary to the prosign K when
there is an immediate response to K. A flash should be
made to K in the message ending when there will be a
delay while checking the message to ensure its
completeness.
NON-DIRECTIONAL PROCEDURE
This procedure permits one station to transmit to
a number of other stations simultaneously by means
of a light showing over a wide area. It is seldom used
at night in wartime because of the danger of enemy
interception. It may be used by day or night in
circumstances where the risk is negligible. The
procedure prescribed for the non-directional flashing
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