Flag semaphore



Contemporary semaphore flag system

The current flag semaphore system uses two short poles with square flags, which a signalman holds in different positions to signal letters of the alphabet and numbers. The signalman holds one pole in each hand, and extends each arm in one of eight possible directions. Except for in the rest position, the flags do not overlap. The flags are colored differently based on whether the signals are sent by sea or by land. At sea, the flags are colored red and yellow (the Oscar flag), while on land, they are white and blue (the Papa flag). Flags are not required; their purpose is to make the characters more obvious.




The sender uses the "Attention" signal to request permission to begin a transmission. The receiver uses a "Ready to receive" signal not shown above to grant permission to begin the transmission. The receiver raises both flags vertical overhead and then drops them to the rest position, once only, to grant permission to send. The sender ends the transmission with the "Ready to receive" signal. The receiver can reply with the "Attention" signal. At this point, sender and receiver change places.

Japanese semaphore

The combination used for オ ("O")


Practical use in communication

Semaphore flags are also sometimes used as means of communication in the mountains where oral or electronic communication is difficult to perform. Although they do not carry flags, the Royal Canadian Mounted Police officers have used hand semaphore in this manner. Some surf-side rescue companies, such as the Ocean City Maryland Beach Patrol, use semaphore flags to communicate between lifeguards.[2] The letters of the flag semaphore are also a common artistic motif. One enduring example is the peace symbol, adopted by the Campaign for Nuclear Disarmament in 1958 from the original logo created by a commercial artist named Gerald Holtom from Twickenham, London.[3] Holtom designed the logo for use on a protest march on the Atomic Weapons Establishment at Aldermaston, near Newbury, England. On 4 April 1958, the march left Trafalgar Square for rural Berkshire, carrying Ban the Bomb placards made by Holtom's children making it the first use of the symbol. Originally, it was purple and white and signified a combination of the semaphoric letters N and D, standing for "nuclear disarmament," circumscribed by a circle.[4]

The album cover for the Beatles' 1965 album Help! was to have portrayed the four band members spelling "help" in semaphore, but the result was deemed aesthetically unpleasing, and their arms were instead positioned in a meaningless but aesthetically pleasing arrangement.[5] Along with Morse code, flag semaphore is currently used by the Navy and also continues to be a subject of study and training for young people of Boy Scouts. In a satirical nod to the flag semaphore's enduring use into the age of the Internet, on April Fools' Day 2007 the Internet Engineering Task Force standards organization outlined the Semaphore Flag Signaling System, a method of transmitting Internet traffic via a chain of flag semaphore operators.[6] The second episode in the second series of Monty Python's Flying Circus depicted famous stories retold using various communication systems, including Wuthering Heights in semaphore.

See also


  2. "Ocean City Beach Patrol Semaphore Alphabet" (PDF). Oceancitymd.gov.
  6. Hofmueller, Jogi; Bachmann, Aaron; Zmoelnig, IOhannes (1 April 2007). The Transmission of IP Datagrams over the Semaphore Flag Signaling Syst em (SFSS). IETF. doi:10.17487/RFC4824. RFC 4824. https://tools.ietf.org/html/rfc4824. Retrieved 20 March 2010.