IMPORTANT NOTICE: This site is scheduled for closure in September 2016.
If you have any comments about the closure, please post them to the newsgroup. See this page for information about the newsgroup and how to post to it.
by Mark Israel
[This is a fast-access FAQ excerpt.]
SOS does NOT stand for "Save Our Ship/Souls", for "Stop Other
Signals", for "Send Our Saviour/Succour", for "Sure of Sinking", or
for the Russian Spasiti Ot Smerti (= "save from death"). The
signal "...---...", recommended for international distress calls at
the international Radio Telegraph Conference of 1906 and officially
adopted in 1908, was not chosen for any alphabetic significance.
Such a signal is now known as a "prosign" (from "procedural
signal"). Those prosigns (such as this one) that are transmitted
without interletter gaps are notated with an overbar. Since
"..." is S and "---" is O in Morse code, the distress signal is
conventionally represented as:
but since there are no interletter gaps, it could also be analysed
as various other combinations of Morse code letters.
Fred Bland writes: "Three of anything (e.g. gun shots, fires,
cairns) is a conventional signal of distress recommended in survival
guides. I don't know whether this convention or the use of three
dots and dashes is older."
Mark Brader writes: "The sign used before SOS was CQD, which
was composed of the usual 'calling' sign CQ, plus D for Distress.
Even in 1912 when the Titanic was sinking, its operator put out a
CQD first and only added SOS after being reminded."
Thomas Hamilton White (email@example.com) writes: "I have
read that the international distress call evolved from SOE (sent as
three letters), which had been used as a distress signal by German
companies. However, because the final E in this sequence consisted
of a single dot, the signal was modified to ...---... to be more
distinctive and symmetrical. [...] I can think of one very practical
reason for continuing to informally treat the distress signal as
SOS -- ever try to stamp ...---... in a snowbank?"
[See some additional "SOS" comments.]