The Telegraph Office

The Telegraph Office Magazine

Volume II, Issue 1

"'SOS,' 'CQD' and the History of Maritime Distress Calls"

by Neal McEwen, K5RW

Copyright © 1997, 1999 Neal McEwen

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Welcome back to the Telegraph Office. This month we are going to diverge a little from talking about wire and wireless artifacts and talk about wireless telegraph distress signals.

Mystery, intrigue as well as misinformation surrounds the origin and use of maritime distress calls. The general populace believes that "SOS" signifies "Save Our Ship." Casual students of radio history are aware that "CQD" preceded the use of "SOS."  Why were these signals adopted? When were they used? Why did one replace the other? What is one likely to find by digging a little deeper? 

The practical use of wireless telegraphy was made possible by Guglielmo Marconi in the closing years of the 19th century. Until then, ships at sea out of visual range were very much isolated from shore and other ships. A ship could vanish from the high seas, and no one would know until that vessel failed to make a port connection. Marconi, seeing that wireless would not compete with wire telegraphy for land based communication, concentrated his efforts on ship to shore communications. Ships equipped with wireless were no longer isolated.

The first use of wireless in communicating the need for assistance came in March of 1899. The East Goodwin Lightship, marking the southeastern English coast, was rammed in a fog in the early morning hours by the SS R. F. Matthews. A distress call was transmitted to a shore station at South Foreland and help was dispatched.

By 1904 there were many Trans-Atlantic British ships equipped with wireless. The wireless operators came from the ranks of railroad and postal telegraphers. In England a general call on the landline wire was a "CQ."  "CQ" preceded time signals and special notices. "CQ" was generally adopted by telegraph and cable stations all over the world. By using "CQ," each station receives a message from a single transmission and an economy of time and labor was realized. Naturally, "CQ" went with the operators to sea and was likewise used for a general call. This sign for "all stations" was adopted soon after wireless came into being by both ships and shore stations.

At the first international congress of wireless telegraphy in 1903, the Italians recommended the use of "SSSDDD" to signal an emergency.  "D" had previously been used internationally as the signal for an urgent message. The origin of "S" is not known, but it may have come from the first letter of the word ship, indicating a ship in distress.  The sending of  "SSSDDD"  would signal all other stations to stop sending and leave the channel open for emergency traffic. Though discussed, it was not adopted. Deciding on a distress signal was put on the agenda for the next meeting in 1906.  "DDD" would later be adopted for the silent signal, indicating all stations must cease sending.

In 1904, the Marconi company filled the gap by suggesting the use of "CQD" for a distress signal.  It was established on February 1 of that year by Marconi Company's circular No. 57.  Although generally accepted to mean, "Come Quick Danger," that is not the case. It is a general call, "CQ," followed by "D," meaning distress. A strict interpretation would be "All stations, Distress."  In the U.S. Senate hearings following the Titanic disaster, interrogator Senator William Smith asked Harold Bride, the surviving wireless operator,  "Is CQD in itself composed of the first letter of three words, or merely a code?"  Bride responded, "Merely a code call sir."  Marconi also testified, "It [CQD] is a conventional signal which was introduced originally by my company to express a state of danger or peril of a ship that sends it."

At the second Berlin Radiotelegraphic Conference of 1906, the subject of a distress signal was again addressed. The distress signal chosen was "SOS."  (The American distress signal "NC" for "Call for help without delay" was not adopted, although it remains as the international flag symbol for distress to this day.)  Popular accounts  portray the adoption of "SOS" as being derived from "SOE," which the Germans had used as a general inquiry call.  These accounts suggest there was objection because the final letter of  "SOE" was a single dot, hard to copy in adverse conditions. The letter "S" was substituted accounts say,  for three dots, three dashes and three dots could not be misinterpreted.

Popular accounts of the origin of "SOS" fail to mention that the Germans had used "SOS" for a distress signal.  They adopted the signal "SOS" for distress as well as "SOE" for inquiry on April 1, 1905, a year before the Berlin conference.  The Electrician, May 5, 1905 published "German Regulations for the Control of Spark Telegraphy" which stated:

"...---..., "Distress" signal (Notzeichen).  This is to be repeated by a ship in distress until all other stations have stopped working."
Unfortunately, the 1906 Conference proceedings do not give an account of the discussions nor the origin of SOS.  The proceedings merely specify what the signal will be.  In the Service Regulations Affixed to the International Wireless Telegraph Convention, paragraph 6a, "Signals of Transmission" states::
"Ships in distress shall use the following signal:  ...---... repeated at brief intervals."
The Marconi Yearbook of Wireless Telegraphy and Telephony , 1918 states, "This signal [SOS] was adopted simply on account of its easy radiation and its unmistakable character. There is no special signification in the letter themselves, and it is entirely incorrect to put full stops between them [the letters]." All the popular interpretations of "SOS," "Save or Ship," "Save Our Souls," or "Send Out Succour" are simply not valid. Stations hearing this distress call were to immediately cease handling traffic until the emergency was over and were likewise bound to answer the distress signal.

Although the use of "SOS" was officially ratified in 1908, the use of "CQD" lingered for several more years, especially in British service where it originated. It is well documented in personal accounts of Harold Bride, second Radio Officer, and in the logs of the SS Carpathia, that the Titanic first used "CQD" to call for help. When Captain Smith gave the order to radio for help, first radio officer Jack Phillips sent "CQD" six times followed by the Titanic call letters, "MGY." Later, at Brides suggestion, Phillips interspersed his calls with "SOS."

In SOS to the Rescue, 1935, author Baarslag notes, "Although adopted intentionally in 1908, it [SOS] had not completely displaced the older "CQD" in the British operators' affections."   Marconi in his U.S. Senate testimony on the Titanic disaster said, "I should state that the international signal [SOS] is really less known that the Marconi Co.'s [CQD] signal."  (It is interesting to observe that Marconi was waiting in New York to return home to England on the Titanic.)

The first use of wireless in the rescue of an American ship was in 1905. Off Nantucket, the operator of Relief Ship No. 58, a light ship, sent "HELP" in International Morse and American Morse. (Trans-Atlantic ships used International Morse and coastal ships used American Morse. The use of American Morse on seagoing vessels ceased in 1912 although it survived for many years on the Great Lakes.) A Naval Radio Station in Rhode Island answered the "HELP" call.

The rescue of 1,500 passengers and crew from the Republic and the Florida by the Baltic in January of 1909, was the defining moment in wireless rescue history.  The White Star liner Republic was rammed in a dense fog by the Italian Florida.  Wireless operator Jack Binns of the Republic, sent out a "CQD."  (The Florida was not wireless equipped.)  The Baltic came to the rescue after hunting for the Republic in the fog for many hours.  Those concerned with the maritime industry now realized the importance of equipping ships with wireless.

The number of ships equipped with wireless grew rapidly after the Republic disaster.   For example, at the end of 1909 the Marconi Co. owned and operated 143 wireless stations on the high seas.  By the summer of 1911, the number grew to 303 stations.  By the end of 1912, there were 580 shipboard wireless installations.

The U.S. Department of Commerce, Bureau of Navigation publication, Important Events in Radio telegraphy, 1916, recorded  maritime disasters in which wireless played a part in rescue on the seas and the Great Lakes.  From 1899 to 1908, there were nine such events.  In 1909 there were 18 rescues and in 1915, 35 rescues.  The following quote, though not directly rescue related, demonstrates the extreme importance of shipboard wireless:

 "November, 1914 -- Great Lakes storms destroyed 19 vessels, none of which were equipped with wireless. All vessels having radio apparatus installed received warning of the coming storm and sought safety."

The first recorded use of "CQD" by an American ship was in 1908 by the steamer Santa Rosa off the coast of California. Commander Richard Johnstone records this in his memoir My San Francisco Story of the Waterfront and the Wireless, 1965. The first recorded American use of "SOS" was in August of 1909. Wireless operator T. D. Haubner of the SS Arapahoe radioed for help when his ship lost its screw near Diamond Shoals, sometimes called the "Graveyard of the Atlantic." The call was heard by the United Wireless station "HA" at Hatteras.

A few months later, the SS Arapahoe received an "SOS" distress call from the SS Iroquois. Radio Officer Haubner therefore has the distinction of being involved in the first two incidents of the use of "SOS" in America, the first as the sender and the second as the receiver.  Being slow to adopt international wireless standards, the U.S. did not officially adopt "SOS" until 1912.

Besides "CQD" and "SOS," "XXX" was used as an urgent signal, being less urgent than "SOS." "XXX" was used when there was concern for the safety of a ship or the safety of person on board or a person sighted from on board.  "TTT" was used as a safety signal to precede ice, storm and other navigational warnings including coastal artillery practice. "MEDICO" was used by ships without a doctor seeking medical advice from another ship or shore station.  During W.W.II, the signal "SSSS" was used for "submarine sited".

The distress call by radio telephone is the two words "MAY DAY." This corresponds to the French pronunciation for "m'aider", which means "help me."  On voice, the "XXX" (urgent) equivalent is the word "PAN." This corresponds to the French pronunciation for "panne", which means "mishap" or "accident."  The "TTT" (safety) equivalent is "SECURITY."  This corresponds to the French pronunciation for "sécurité", which means "safety." The calling frequency for voice was 2182 kilohertz.

During the investigation into the Titanic disaster, Guglielmo Marconi stated that he was experimenting with a device that could be used as an automated alarm for distress signals.  Upon hearing a series of signals, an alarm bell would ring.  Some European nations put these alarms into service.  A sequencing device was connected to the output of the receiver. Upon the reception of four or more dashes of exactly four seconds duration, a device rang an alarm bell in the radio shack, the radio officer's quarters and on the ship's bridge. The system was employed as a substitute for a second operator. Because the system could miss a call under adverse conditions or ring the bell in error, American radio authorities deemed it unreliable and not a substitute for another on duty operator.  Americans later mandated the used of automatic alarms with the Communications Act of 1934.

At the third international radiotelegraph conference in 1912, it was agreed that ships would listen for distress signals on a wavelength of 600 meters. This is a frequency of about 500 kilohertz.  (The calling and distress frequency for the Great Lakes was 410 kilohertz.)  International law required each ship to cease transmitting for three minutes at 15 and 45 minutes past the hour. During this interval they were required to listen for distress calls. At this conference, the recent Titanic disaster was fresh on the minds of the delegates, particularly the British. Consequently, many advances were made concerning the cooperative use of wireless for safety at sea.

It is interesting that the use of "CQ" as a general call was displaced by "QST" in 1911. Radio amateurs, or hams as they are more commonly called, continue to use both. "CQ" is used as "calling any station" and "QST" is used as "calling all stations"

Wireless and radio literature of the early and mid 20th century is rich in documenting the use of maritime distress signals. Only the surface of the subject is covered here. Yet, perhaps next time a reference to "SOS" is seen, there will be a little more appreciation of its lineage.

Special thanks to Thomas White for providing electronic copies of German Regulations for the Control of Spark Telegraphy, Important Events in Radiotelegraphy and International Wireless Telegraph Convention.  Without them, this article would not have been complete.


Baarslag, Karl. SOS to the Rescue. New York: Oxford University Press, 1935.

DeNeuf, Don. SSSDDD? SOE? CQD? SOS?.  Telecommunications, Old Timer's Bulletin, Vol. 30. No. 2, Antique Wireless Association, 1989.

End of SOS Recalls Early Origins. Dots and Dashes - Official Publication of the Morse Telegraph Club, Inc. Vol. 27. No. 1, 1999.

"German Regulations for the Control of Spark Telegraphy." The Electrician, May, 1905.

Hancock, H. E. Wireless at Sea, The First Fifty Years. Chelmsford, England: Marconi International Marine Communications Company, 1950.

Important Events in Radiotelegraphy, Department of Commerce, Bureau of Navigation, Radio Service, Washington: G.P.O., 1916.

International Wireless Telegraph Convention. Washington: G.P.O., 1907.

Johnstone, Richard. My San Francisco Story of the Waterfront and the Wireless. Larkspur, California: Richard Johnstone, 1965.

Kuntz, Tom. (editor) The Titanic Disaster Hearings: The Official Transcripts of the 1912 Senate Investigation.  Pocket Books, 1998.

"Marconi's Latest -- Wireless Distress Signal That Rings a Bell -- Titanic Commission Hears of New Invention."  Daily Sketch (British newspaper) 19 June 1912. from The Titanic Disaster - As Reported in the British National Press April - July 1912. compiled by Dave Bryceson. New York: Norton, 1997

Morgan, Alfred P. Wireless Telegraphy and Telephony. New York: Henley, 1920.

Nilson, Arthur R. and Hornung, J. L. Radio Operating Questions and Answers. New York: McGraw-Hill, 1940.

Olson, Hank and Orr, Bill. The KFS-Federal-MacKay Story: From CW Arc to Silicon Valley.  The AWA Review, Vol. 8, 1993.

Schroeder, Peter B. Contact at Sea, A History of Maritime Radio Communications. Ridgewood, N.J.: The Gregg Press, 1967.

Strichartz, M. H. Marine Radio Manual. New York: Cornell Maritime Press, 1944

The Year-Book of Wireless Telegraphy & Telephony 1918. London: The Wireless Press, LTD., 1918.


Collins, Francis A. The Wireless Man His Work and Adventures on Land and Sea (Boy Scout edition). Grosset & Dunlap, 1912 

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