Croydon Airport known as London Terminal Aerodrome or London Airport was the UK's major international airport during the interwar period, located in South London, England. At the launch of the first international air services after the First World War, it was developed as Britain's main airport. After the Second World War, it was replaced by Northolt Aerodrome, London Heathrow Airport and Gatwick Airport. In 1978, the terminal building and Gate Lodge were granted protection as Grade II listed buildings. In May 2017, Historic England raised the status of the terminal building to Grade II*. Owing to disrepair, the Gate Lodge is now classified as Heritage at Risk by Historic England. Funding would be received from John Power. In December 1915, Beddington Aerodrome was established – one of a number of small airfields around London that were created for protection against Zeppelin airship raids during the First World War. In January 1916, the first two aircraft, B. E 2C's, arrived at the aerodrome as part of Home Defence.
Waddon Aerodrome opened in 1918 as part of the adjoining National Aircraft Factory No. 1, to serve aircraft test flights. The two airfields were on each side of Plough Lane. Beddington Aerodrome became a large Reserve Aircraft and Training aerodrome for the Royal Flying Corps. At the end of the First World War the aerodrome was retained, becoming an important training airfield for the newly formed Royal Air Force. During 1919, HRH Prince Albert gained his "wings" here with No. 29 Training Squadron, the first member of the Royal Family to learn to fly. His elder brother, HRH Prince of Wales received flying training with No. 29 Training Squadron at Beddington during 1919. The two aerodromes were combined following the end of the First World War to become Croydon Aerodrome, the gateway for all international flights to and from London; the new aerodrome opened on 29 March 1920 replacing the temporary civil aerodrome at a Cavalry ground on Hounslow Heath. Plough Lane remained a public road crossing the site, road traffic was halted when necessary, first by a man with a red flag and by a gate.
The aerodrome stimulated a growth in regular scheduled flights carrying passengers and freight, the first destinations being Paris and Rotterdam. Two flights daily from Paris were scheduled for ease of communication with London during the Paris Peace Conference. In 1923, flights to Berlin Tempelhof Airport began. Penshurst Airfield was an alternative destination for airliners when Croydon was closed on account of fog. One such diversion was on 24 September 1921, when a de Havilland DH.18 aircraft was diverted to Penshurst. This situation lasted until Penshurst closed on 28 July 1936. Croydon was the first airport in the world to introduce air traffic control, a control tower, radio position-fixing procedures. On the formation of Britain's first national airline, Imperial Airways, on 31 March 1924, Croydon became the new airline's operating base. Imperial Airways was the British Government's chosen instrument to develop connections with the U. K.'s extensive overseas interests. It was therefore from Croydon that Britain first developed its European and longhaul routes to India, the Middle and Far East, Asia and Australia.
Following the Imperial Airways de Havilland DH.34 crash of December 1924, Britain's first major civil aviation accident, conditions at Croydon came under criticism from the public inquiry that investigated the causes. The inquiry was Britain's first into an aviation accident which led to an Act of Parliament, the Croydon Aerodrome Extension Act 1925; the Croydon Aerodrome Extension Act led to large scale expansion and construction of an improved new airport with airport buildings constructed adjacent to the Purley Way, Croydon. Under the provisions of the Croydon Aerodrome Extension Act 1925, the airport was enlarged between 1926 and 1928, with a new complex of buildings being constructed alongside Purley Way, including the first purpose-designed airport terminal and air traffic control tower, the world's first airport hotel, extensive hangars; the development cost £267,000. Plough Lane was closed permanently to depart safely; the airport's terminal building and control tower were completed in 1928, the old wooden air traffic control and customs building demolished.
The new buildings and layout began operations on 20 January 1928, were opened on 2 May 1928 by Lady Maud Hoare. Croydon was where regular international passenger services began using converted wartime bombers, the Croydon–Le Bourget route soon became the busiest in the world. Air traffic control was first developed here. Amy Johnson took off from Croydon on 5 May 1930 for her record-breaking flight to Australia. In 1927, Charles Lindbergh arrived in Spirit of St. Louis, to be greeted by an enthusiastic crowd of over 100,000 people. Winston Churchill took flying lessons. On the morning of 11 July 1936, Major Hugh Pollard, Cecil Bebb left Croydon Airport for the Canary Islands in a de Havilland Dragon Rapide aircraft, where they picked up General Francisco Franco, taking him to Spanish Morocco and thereby helping to trigger the outbreak of the Spanish Civil War. Imperial Airways used the Handley Page HP42/HP45 four-engined biplanes from Croydon, the Armstrong Whitworth Atalanta, the first monoplane airliner used by the airline, intended for use on the African routes.
In March 1937 British Airways Ltd operated from Croydon, moving to Heston Aerodrome in May 1938. Imperial Airways, serving routes in the British Empir
Sunshine Skyway Bridge
The Bob Graham Sunshine Skyway Bridge referred to as the Sunshine Skyway Bridge or the Skyway, is a cable-stayed bridge spanning the Lower Tampa Bay connecting St. Petersburg, Florida to Terra Ceia; the four-lane bridge carries Interstate 275 and U. S. Route 19, passing through Pinellas County, Hillsborough County, Manatee County; the current Sunshine Skyway is the second bridge of that name on the site. It was designed by the Figg & Muller Engineering Group and built by the American Bridge Company and is considered a symbol of Florida; the original bridge opened in 1954 and was the site of two major maritime disasters within a few months in 1980. In January 1980, the United States Coast Guard Cutter Blackthorn collided with the tanker Capricorn near the bridge, resulting in the sinking of the cutter and the loss of 23 crew members. In May 1980, the freighter MV Summit Venture collided with a bridge support during a sudden squall, resulting in the structural collapse of the southbound span and the deaths of 35 people whose vehicles plunged into Tampa Bay.
The original two-lane bridge was built by the Virginia Bridge Company and opened to traffic on September 6, 1954, with a similar structure built parallel and to the west of it in 1969 to make it a four-lane bridge and bring it to Interstate Highway standards. Opening of the newer span was delayed until 1971 for reinforcing of the south main pier, which had cracked due to insufficient supporting pile depth; the second span was used for all southbound traffic, while the original span was converted to carry northbound traffic. The old bridge replaced a ferry from Point Pinellas to Piney Point. US 19 was extended from St. Petersburg to its current end north; the southbound span of the original bridge was destroyed at 7:33 a.m. on May 9, 1980, when the freighter MV Summit Venture collided with a pier during a sudden squall, sending over 1,200 feet of the bridge plummeting into Tampa Bay. The collision caused six cars, a truck, a Greyhound bus to fall 150 feet into the water, killing 35 people. One man, Wesley MacIntire, survived when his Ford Courier pickup truck landed on the deck of the Summit Venture before falling into the bay.
He sued the company that owned the ship, settled in 1984 for $175,000. Several other drivers - including former major league baseball player Granny Hamner - were able to stop their vehicles before reaching the gap in the roadway. John Lerro, the harbor pilot, steering the ship, was cleared of wrongdoing by both a state grand jury and a Coast Guard investigation. A microburst had hit the freighter with torrential rains and 70 mile per hour winds as it was in the middle of a turn in the shipping channel nearing the bridge, cutting visibility to near zero and temporarily rendering the ship's radar useless. Lerro put the ship's engines into full reverse and ordered the emergency dropping of the anchor as soon as he realized that the freighter was out of the channel, but the bow still hit two support piers with enough force to cause a portion of the roadway to collapse; the south main pier withstood the ship strike without significant damage, but a secondary pier to the south was not designed to withstand such an impact and failed catastrophically.
After the Summit Venture disaster, the southbound span was used as a temporary fishing pier and the northbound span was converted back to carry one lane in either direction until the current bridge opened. Before the old bridge was demolished and hauled away in barges, MacIntire was the last person to drive over it, he was accompanied by his wife, when they reached the top of the bridge, they dropped 35 white carnations into the water, one for each person who died in the disaster. Both the main spans of both the intact northbound bridge and the damaged southbound bridge were demolished in 1993 and the approaches for both old spans were made into the Skyway Fishing Pier State Park; these approaches sit 1⁄2 mile to the west of the current bridge. The approaches of the 1950 span were demolished in 2008. Gov. Graham's idea for the design of the current bridge won out over other proposals, including a tunnel and a simple reconstruction of the broken section of the old bridge that would not have improved shipping conditions.
The new bridge's main span is 50% wider than the old bridge. The piers of the main span and the approaches for 1⁄4 mile in either direction are surrounded by large concrete barriers, called "dolphins", that can protect the bridge piers from collisions by ships larger than the Summit Venture like tankers, container ships, cruise ships. In 1990 FDOT awarded the winning bid to the Hardaway Company to demolish all steel and concrete sections of the Sunshine Skyway Bridge; the scope of the project required that all underwater piles and piers, surface roadway and beams be dismantled. Special care had to be taken in removing underwater bridge elements near the shipping channel. Additionally, the concrete material, deck sections and steel girders were to be collected in order to be placed offshore and along the remaining bridge approaches to become artificial reefs for the new planned state fishing park; the main bridge span had to be removed in one piece in order not to block the main shipping canal leading to the Port of Tampa.
During the disassembly work of the bridges’ structural steel members, several difficult engineering challenges had to be resolved: the order of disassembly, a safe method for detonating charges on concrete and steel members in a publicly open and difficult to control area such as the Tampa Bay, the development of a safe methodology for the removal in one piece
The Geneva Conventions comprise four treaties, three additional protocols, that establish the standards of international law for humanitarian treatment in war. The singular term Geneva Convention denotes the agreements of 1949, negotiated in the aftermath of the Second World War, which updated the terms of the two 1929 treaties, added two new conventions; the Geneva Conventions extensively defined the basic rights of wartime prisoners, established protections for the wounded and sick, established protections for the civilians in and around a war-zone. The treaties of 1949 were ratified, by 196 countries. Moreover, the Geneva Convention defines the rights and protections afforded to non-combatants, because the Geneva Conventions are about people in war, the articles do not address warfare proper—the use of weapons of war—which is the subject of the Hague Conventions, the bio-chemical warfare Geneva Protocol; the Swiss businessman Henry Dunant went to visit wounded soldiers after the Battle of Solferino in 1859.
He was shocked by the lack of facilities and medical aid available to help these soldiers. As a result, he published his book, A Memory of Solferino, on the horrors of war, his wartime experiences inspired Dunant to propose: A permanent relief agency for humanitarian aid in times of war A government treaty recognizing the neutrality of the agency and allowing it to provide aid in a war zoneThe former proposal led to the establishment of the Red Cross in Geneva. The latter led to the 1864 Geneva Convention, the first codified international treaty that covered the sick and wounded soldiers in the battlefield. On 22 August 1864, the Swiss government invited the governments of all European countries, as well as the United States and Mexico, to attend an official diplomatic conference. Sixteen countries sent a total of twenty-six delegates to Geneva. On 22 August 1864, the conference adopted the first Geneva Convention "for the Amelioration of the Condition of the Wounded in Armies in the Field".
Representatives of 12 states and kingdoms signed the convention: For both of these accomplishments, Henry Dunant became corecipient of the first Nobel Peace Prize in 1901. On 20 October 1868 the first, attempt to expand the 1864 treaty was undertaken. With the'Additional Articles relating to the Condition of the Wounded in War' an attempt was initiated to clarify some rules of the 1864 convention and to extend them to maritime warfare; the Articles was only ratified by the Netherlands and North America. The Netherlands withdrew their ratification; the protection of the victims of maritime warfare would be realized by the third Hague Convention of 1899 and the tenth Hague Convention of 1907. In 1906 thirty-five states attended. On 6 July 1906 it resulted in the adoption of the "Convention for the Amelioration of the Condition of the Wounded and Sick in Armies in the Field", which improved and supplemented, for the first time, the 1864 convention, it remained in force until 1970. The 1929 conference yielded two conventions that were signed on 27 July 1929.
One, the "Convention for the Amelioration of the Condition of the Wounded and Sick in Armies in the Field", was the third version to replace the original convention of 1864. The other was adopted after experiences in World War I had shown the deficiencies in the protection of prisoners of war under the Hague Conventions of 1899 and 1907; the "Convention relative to the Treatment of Prisoners of War" was not to replace these earlier conventions signed at The Hague, rather it supplemented them. Inspired by the wave of humanitarian and pacifistic enthusiasm following World War II and the outrage towards the war crimes disclosed by the Nuremberg Trials, a series of conferences were held in 1949 reaffirming and updating the prior Geneva and Hague Conventions, it yielded four distinct conventions: The First Geneva Convention "for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field" was the fourth update of the original 1864 convention and replaced the 1929 convention on the same subject matter.
The Second Geneva Convention "for the Amelioration of the Condition of Wounded and Shipwrecked Members of Armed Forces at Sea" replaced the Hague Convention of 1907. It was the first Geneva Convention on the protection of the victims of maritime warfare and mimicked the structure and provisions of the First Geneva Convention; the Third Geneva Convention "relative to the Treatment of Prisoners of War" replaced the 1929 Geneva Convention that dealt with prisoners of war. In addition to these three conventions, the conference added a new elaborate Fourth Geneva Convention "relative to the Protection of Civilian Persons in Time of War", it was the first Geneva Convention not to deal with combatants, rather it had the protection of civilians as its subject matter. The 1899 and 1907 Hague Conventions had contained some provisions on the protection of civilians and occupied territory. Article 154 provides that the Fourth Geneva Convention is supplementary to these provisions in the Hague Conventions.
Despite the length of these documents, they were found over time to be incomplete. In fact, the nature of armed conflicts had changed with the beginning of the Cold War era, leading many to believe that the 1949 Geneva Conventions were addressing a extinct reality: on the one hand, most armed conflicts had
Swissair Flight 111
Swissair Flight 111 was a scheduled international passenger flight from John F. Kennedy International Airport in New York City, United States to Cointrin International Airport in Geneva, Switzerland; this flight was a codeshare flight with Delta Air Lines. On 2 September 1998, the McDonnell Douglas MD-11 performing this flight, registration HB-IWF, crashed into the Atlantic Ocean southwest of Halifax International Airport at the entrance to St. Margarets Bay, Nova Scotia; the crash site was 8 kilometres from shore equidistant from the tiny fishing and tourist communities of Peggy's Cove and Bayswater. All 229 passengers and crew onboard the MD-11 were killed, making the crash the deadliest McDonnell Douglas MD-11 accident in aviation history; the search and rescue response, crash recovery operation, investigation by the Government of Canada took more than four years and cost $57 million CAD. The investigation carried out by the Transportation Safety Board of Canada concluded that flammable material used in the aircraft's structure allowed a fire to spread beyond the control of the crew, resulting in the crash of the aircraft.
Several wide-ranging recommendations were made which have been incorporated into new US Federal Aviation Administration standards. Swissair Flight 111 was known as the "UN shuttle" because of its popularity with United Nations officials; the aircraft, a 7-year old McDonnell Douglas MD-11, serial number 48448, registration HB-IWF, was manufactured in 1991, Swissair was its only operator. It bore the title of Vaud, in honour of the Swiss canton of the same name; the cabin was configured with 241 passenger seats. First and business class seats were equipped with in-seat in-flight entertainment systems from Interactive Flight Technologies; the aircraft was powered by three Pratt & Whitney 4462 turbofan engines and had logged over 36,000 hours before the crash. The in-flight entertainment system was the first of its kind equipped on the plane, it allowed the first and business class passengers to browse the web, select their own movies and games, gamble. The system was installed in business class one year before the incident, between 21 August and 9 September 1997.
It was installed in first class five months in February 1998, due to delivery delays. The pilot-in-command was 50-year-old Urs Zimmermann. At the time of the accident, he had 10,800 hours of total flying time, of which 900 hours were in an MD-11, he was an instructor pilot for the MD-11. Before his career with Swissair, he was a fighter pilot in the Swiss Air Force. Zimmermann was described as a friendly person with professional skills, who always worked with exactness and precision; the first officer, 36-year-old Stefan Löw, had 4,800 hours of total flying time, including 230 hours on the MD-11. He was an instructor on the MD-80 and A320. From 1982 to 1990, he had been a pilot in the Swiss Air Force; the cabin crew comprised a maître de cabine and eleven flight attendants. All crew members on board Swissair Flight 111 were qualified and trained in accordance with Swiss regulations under the Joint Aviation Authorities; the flight took off from New York's John F. Kennedy International Airport at 20:18 EDT on 2 September.
From 20:33 – 20:47 EDT, the aircraft experienced a radio blackout for thirteen minutes, found to be caused by communication radio tuning errors. At 22:10 AT, the flight crew detected an odor in the cockpit and determined it to be smoke from the air conditioning system. Four minutes the odor returned and smoke became visible, prompting the pilots to make a "pan-pan-pan" radio call to Moncton air traffic control, the area control center station in charge of air traffic over the Canadian province of Nova Scotia; the pan-pan-pan call indicated that there was an urgency due to smoke in the cockpit but did not declare an emergency as denoted by a "Mayday" call. The crew requested a diversion to Logan International Airport in Boston before accepting Moncton ATC's offer of radar vectors to the closer Halifax International Airport in Enfield, Nova Scotia, 66 nautical miles away. At 22:18 AT, Moncton Center handed over traffic control of the plane to Halifax terminal air traffic control, the ATC station in charge of controlling traffic in and out of Halifax International Airport.
Upon being advised by Halifax ATC that they were 30 nautical miles from the airport, the crew requested more flight distance to allow the aircraft to descend safely from its altitude of 21000 ft at the time. The crew requested to dump fuel to reduce their weight for landing. Halifax thus vectored the plane south toward St. Margaret's Bay where it was safe for the aircraft to dump fuel while remaining within 40 nautical miles of the airport. In accordance with the Swissair checklist'In case of smoke of unknown origin', the crew shut off power to the cabin, which turned off the recirculating fans in the cabin's ceiling; this allowed the fire to spread to the cockpit shutting off power to the aircraft's autopilot. At 22:24:28 AT, the crew informed Halifax that "we now must fly manually", followed by declaring an emergency. Ten seconds the crew declared an emergency again, saying "...and we are declaring emergency now, Swissair one eleven". The aircraft flight data recorder stopped operating at 22:25:40 AT, followed one second by the cockpit voice recorder.
The aircraft's transponder resumed transmission
MV Summit Venture
The M/V Summit Venture was a bulk carrier built in 1976, in Nagasaki, Japan. She was 579.8 feet long, beam of 85.5 feet, displacement of 19,734 tons. She would cruise at 10.9 knots at 50 % power. Summit Venture was involved in a fatal collision with a bridge in Tampa Bay, Florida, on May 9, 1980. While negotiating a required turn in the narrow channel during a storm, the radar failed, the freighter struck one of the piers on the southbound span of the original Sunshine Skyway Bridge. 1,400 feet of the steel cantilever highway bridge collapsed, causing a Greyhound bus, six other vehicles, to fall 165 feet into the bay. A total of 35 people died; the pilot of the Summit Venture on that day was John E. Lerro, he was cleared of wrongdoing by both a Coast Guard investigation. In 2016 the book titled Skyway: The True Story of Tampa Bay's Signature Bridge and the Man Who Brought It Down shed new light on what transpired on the day of the accident. Although Capt. Lerro resumed his shipping duties soon afterward, he was forced to retire months by the onset of multiple sclerosis, dying from complications caused by the disease on August 31, 2002, at the age of 59.
Wesley MacIntire was the only person. His vehicle hit the Summit Venture's deck before falling into Tampa Bay, he sued the company that owned the ship, settled for $175,000 in 1984. He died in 1989. A new bridge was completed in 1987 to replace the old. Several safeguards were included in the design to prevent a repeat occurrence of the Summit Venture incident, such as the installation of massive concrete bumpers or "dolphins" around the main span's piers to mitigate collisions; the Summit Venture, after having her hull repaired, continued service under the Liberian flag for another 13 years. Her last return to Tampa Bay was in 1990 for a Coast Guard inspection; the ship was sold to Greek interests in 1993, rechristened Sailor 1, predominantly plying the waters off the west coast of the U. S. In 2004, the ship was sold to a Singapore firm, it was renamed the KS Harmony, sailed in the Caribbean. It was sold to Jian Mao Intl. Renamed the Jian Mao 9 and was lost in a storm without loss of life off the coast of Vietnam in December 2010
Morse code is a character encoding scheme used in telecommunication that encodes text characters as standardized sequences of two different signal durations called dots and dashes or dits and dahs. Morse code is named for Samuel F. B. Morse, an inventor of the telegraph; the International Morse Code encodes the 26 English letters A through Z, some non-English letters, the Arabic numerals and a small set of punctuation and procedural signals. There is no distinction between lower case letters; each Morse code symbol is formed by a sequence of dashes. The dot duration is the basic unit of time measurement in Morse code transmission; the duration of a dash is three times the duration of a dot. Each dot or dash within a character is followed by period of signal absence, called a space, equal to the dot duration; the letters of a word are separated by a space of duration equal to three dots, the words are separated by a space equal to seven dots. To increase the efficiency of encoding, Morse code was designed so that the length of each symbol is inverse to the frequency of occurrence in text of the English language character that it represents.
Thus the most common letter in English, the letter "E", has the shortest code: a single dot. Because the Morse code elements are specified by proportion rather than specific time durations, the code is transmitted at the highest rate that the receiver is capable of decoding; the Morse code transmission rate is specified in groups per minute referred to as words per minute. Morse code is transmitted by on-off keying of an information carrying medium such as electric current, radio waves, visible light or sound waves; the current or wave is present during time period of the dot or dash and absent during the time between dots and dashes. Morse code can be memorized, Morse code signalling in a form perceptible to the human senses, such as sound waves or visible light, can be directly interpreted by persons trained in the skill; because many non-English natural languages use other than the 26 Roman letters, Morse alphabets have been developed for those languages. In an emergency, Morse code can be generated by improvised methods such as turning a light on and off, tapping on an object or sounding a horn or whistle, making it one of the simplest and most versatile methods of telecommunication.
The most common distress signal is SOS – three dots, three dashes, three dots – internationally recognized by treaty. Early in the nineteenth century, European experimenters made progress with electrical signaling systems, using a variety of techniques including static electricity and electricity from Voltaic piles producing electrochemical and electromagnetic changes; these numerous ingenious experimental designs were precursors to practical telegraphic applications. Following the discovery of electromagnetism by Hans Christian Ørsted in 1820 and the invention of the electromagnet by William Sturgeon in 1824, there were developments in electromagnetic telegraphy in Europe and America. Pulses of electric current were sent along wires to control an electromagnet in the receiving instrument. Many of the earliest telegraph systems used a single-needle system which gave a simple and robust instrument. However, it was slow, as the receiving operator had to alternate between looking at the needle and writing down the message.
In Morse code, a deflection of the needle to the left corresponded to a dot and a deflection to the right to a dash. By making the two clicks sound different with one ivory and one metal stop, the single needle device became an audible instrument, which led in turn to the Double Plate Sounder System; the American artist Samuel F. B. Morse, the American physicist Joseph Henry, Alfred Vail developed an electrical telegraph system, it needed a method to transmit natural language using only electrical pulses and the silence between them. Around 1837, therefore, developed an early forerunner to the modern International Morse code. William Cooke and Charles Wheatstone in England developed an electrical telegraph that used electromagnets in its receivers, they obtained an English patent in June 1837 and demonstrated it on the London and Birmingham Railway, making it the first commercial telegraph. Carl Friedrich Gauss and Wilhelm Eduard Weber as well as Carl August von Steinheil used codes with varying word lengths for their telegraphs.
In 1841, Cooke and Wheatstone built a telegraph that printed the letters from a wheel of typefaces struck by a hammer. The Morse system for telegraphy, first used in about 1844, was designed to make indentations on a paper tape when electric currents were received. Morse's original telegraph receiver used a mechanical clockwork to move a paper tape; when an electrical current was received, an electromagnet engaged an armature that pushed a stylus onto the moving paper tape, making an indentation on the tape. When the current was interrupted, a spring retracted the stylus and that portion of the moving tape remained unmarked. Morse code was developed so that operators could translate the indentations marked on the paper tape into text messages. In his earliest code, Morse had planned to transmit only numerals and to use a codebook to look up each word according to the number, sent. However, the code was soon expanded by Alfred Vail in 1840 to include letters and special characters so it could be used more generally.
Vail estimated the frequency of use of letters in the English language by counting the movable type he found in the type-cases of a local newspaper in Morristown. The shorter marks were called "dots" and the longer ones "dashes", the letters most used were assigned the shorter sequences of dots and dashes; this code was used since 1844 and became known as Morse lan
SOS is the International Morse code distress signal. It is used as a start-of-message mark for transmissions requesting help when loss of life or catastrophic loss of property is imminent. Other prefixes are assigned for mechanical breakdowns, requests for medical assistance, a relayed distress signal sent by another station; this distress signal was first adopted by the German government radio regulations effective 1 April 1905, became the worldwide standard under the second International Radiotelegraphic Convention, signed on 3 November 1906, became effective on 1 July 1908. SOS remained the maritime radio distress signal until 1999, when it was replaced by the Global Maritime Distress and Safety System. SOS is still recognized as a standard distress signal; the SOS distress signal is a continuous sequence of three dots, three dashes, three dots, with no spaces between the letters. In International Morse Code, three dots form the letter S, three dashes make the letter O, so "S O S" became a way to remember the order of the dots and dashes.
In modern terminology, SOS is a Morse "procedural signal" or "prosign", the formal way to write it is with a bar above the letters or enclosed in angle brackets: SOS or <SOS>. Though SOS does not stand for anything, in popular usage it became associated with such phrases as "Save Our Souls" and "Save Our Ship". SOS is only one of several ways; the use of the SOS signal was first introduced in Germany as part of a set of national radio regulations, effective 1 April 1905. These regulations introduced three new Morse code sequences, including the SOS distress signal. In 1906, at the second International Radiotelegraphic Convention in Berlin, an extensive collection of Service Regulations was developed to supplement the main agreement, signed on 3 November 1906, becoming effective on 1 July 1908. Article XVI of the regulations adopted Germany's Notzeichen as the international standard, reading: "Ships in distress shall use the following signal: ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ repeated at brief intervals".
The first ship to transmit an SOS distress call appears to have been either the Cunard liner RMS Slavonia on 10 June 1909, according to Notable Achievements of Wireless in the September 1910 Modern Electrics, or the steamer SS Arapahoe on 11 August 1909. The signal of the Arapahoe was received by the United Wireless Telegraph Company station at Hatteras, North Carolina, forwarded to the steamer company's offices. However, there was some resistance among the Marconi operators to the adoption of the new signal, and, as late as the April 1912 sinking of the RMS Titanic, the ship's Marconi operators intermixed CQD and SOS distress calls. However, in the interests of consistency and water safety, the use of CQD appears to have died out thereafter. In both the 1 April 1905 German law and the 1906 international regulations, the distress signal was specified as a continuous Morse code sequence of three dots / three dashes / three dots, with no mention of any alphabetic equivalents. However, in International Morse, three dots comprise the letter "S", three dashes the letter "O".
It therefore soon became common to refer to the distress signal as "S O S". An early report on The International Radio-Telegraphic Convention in the 12 January 1907, Electrical World stated that "Vessels in distress use the special signal, SOS, repeated at short intervals." In contrast to CQD, sent as three separate letters with spaces between each letter, the SOS distress call has always been transmitted as a continuous sequence dits and dahs, not as individual letters. There was no problem as long as operators were aware that the notation "SOS" is just a convenient way for remembering the proper sequence of the distress signal's total of nine dits and dahs. In years, the number of special Morse symbols increased. In order to designate the proper sequence of dits and dahs for a long special symbol, the standard practice is to list alphabetic characters that contain the same series of dits and dahs, in the same order, with a bar atop the character sequence to indicate that the sequence is a digraph and there should not be any internal spaces in the transmission.
Thus, under the modern notation, the distress signal becomes SOS. In International Morse Code, VTB, IJS, VGI, SMB, VZE all convert to the ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ distress-call sequence, but traditionally only SOS is used, it has sometimes been used as a visual distress signal – consisting of three short, three long, three more short flashes of light, such as from a survival mirror, or with "S O S" spelled out in individual letters. The fact that the letters "S O S" can be read right side up as well as upside down became important for visual recognition if viewed from above. Additional warning and distress signals followed the introduction of SOS. On 20 January 1914, the London International Convention on Safety of Life at Sea adopted the Morse code signal TTT, three letter Ts spaced as three letters so as not to be confused with the letter O, as the "Safety Signal", used for m