Jan. 7, 1904: A Distress Call for Ships in Danger Upon the Sea

1904: "CQD" is adopted as the international distress signal for the operators of Marconi wireless installations.
The Morse code signal (dash-dot-dash-dot, dash-dash-dot-dash, dash-dot-dot), which became effective Feb. 1, was approved for maritime use by the Marconi International Marine Communications Company. Although widely used by Marconi operators, CQD never became a true international standard.
Two years later, members of the International Radiotelegraphic Convention meeting in Berlin adopted SOS as the standard distress signal, and CQD began fading from the scene.
CQD originated by combining CQ, which alerted stations that a message was incoming, with D for "distress." SOS, on the other hand, represents the Morse equivalents for those letters (dot-dot-dot, dash-dash-dash, dot-dot-dot). It does not stand for either "Save Our Ship" or "Save Our Souls." SOS was adopted because it's easy to send and easy to decipher.
SOS remained the maritime distress signal until 1999, when it was replaced by the Global Maritime Distress and Safety System.
The most famous maritime distress call of all time was sent by the RMS Titanic following its fatal collision with an iceberg in April 1912. In that instance, Marconi radio operator Jack Phillips began by sending the CQD signal, then still commonly used aboard British ships. On the suggestion of his junior, Harold Bride, Phillips began alternating between CQD and SOS.
Both signals were received, and the ships that could responded, but ...
(Source: Various)
ΠΗΓΗ ----->http://www.wired.com/science/discoveries/news/2008/01/dayintech_0107#

The RMS Titanic leaves Belfast, 1912.
Photo: Courtesy of U.S. National Archives and Records Administration