Radiotelephone procedure Page: 49
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RADIOTELEPHONE PROCEDURE
facilities, including CAA stations, to get information to pilot or to
reestablish contact.
105. Distress signals.-Listed below are extracts from the general
radio regulations pertaining to safety of aircraft:
a. In radiotelegraphy, the distress signal shall consist of the group
. . . ... transmitted as one signal, in which the dashes must
be emphasized so as to be distinguished clearly from the dots.. This
signal is often referred to as SOS. Actually SOS is meaningless.
VTB, 3B, STMS, or any other combination would produce the same
signal, but inasmuch as it has been customary to refer to the distress
signal as SOS no attempt is being made to eliminate it. It should be
borne in mind, however, that the signal is sent as one character. If
it is to be recorded it may be written as SOS.
b. In radiotelephony, the distress signal shall consist of the spoken
expression MAYDAY.
c. These distress signals shall announce that the ship, aircraft, or
any other vehicle which sends the distress signal is threatened by
serious and imminent danger and requests immediate assistance.
d. This call shall have absolute priority over other transmissions.
All stations hearing it must immediately cease all transmissions
capable of interfering with the distress traffic, and must listen on the
frequency used for the distress call.
e. The distress call must be followed as soon as possible by the
distress message. This message shall include the distress call followed
by the name of the ship, aircraft, or other vehicle in distress, informa-
tion regarding the position of the latter, the nature of the distress and
the nature of the help requested, and any other further information
which might facilitate this assistance.
J. When, in its distress message, an aircraft is unable to signal its
position, it shall endeavor after the transmission of the incomplete
message to send its call signal long enough so that the radio direction-
finding stations may determine its position.
g. As a general rule, a ship or aircraft at sea shall signal its position
in latitude and longitude (Greenwich) using figures, for the degrees
and minutes, accompanied by one of the words North or South and
one of the words East or West. A period shall separate the degrees
from the minutes. In some cases, the true bearings and the distance
in nautical miles from some known geographical point may be given.
h. As a general, rule, an aircraft flying over land shall signal its
position by the name of the nearest locality, its approximate distance
from this point, accompanied, according to the case, by one of the
words North, South, East or West, or, in some cases, words indicating
intermediate directions.530334 0---43----4
104-105
49
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United States. War Department. Radiotelephone procedure, book, March 20, 1943; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc96658/m1/51/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.