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Fair Isle

Fair Isle (Friðarey; Fara), sometimes Fairisle, is the southernmost Shetland island, situated roughly 38 km from the Shetland Mainland and about 43 km from North Ronaldsay (the most northerly island of Orkney).

The entire archipelago lies off the northernmost coast of Scotland, in the North Sea. As the most remote inhabited island in the United Kingdom (and among the most northerly settlements in Great Britain), Fair Isle is known for its wild bird observatory, interesting historic shipwrecks, Scottish and Shetland-style traditional music, and its traditional style of knitting. The island has been owned by the National Trust for Scotland since 1954.

History
Fair Isle has been occupied since Neolithic times, which is remarkable given the lack of raw materials on the island, although it is surrounded by rich fishing waters. There are two known Iron Age sites: a promontory fort at Landberg and the foundations of a house underlying an early Christian settlement at Kirkigeo.

Most of the place names date from after the 9th-century Norse settlement of the Northern Isles. By that time the croft lands had clearly been in use for centuries.

Between the 9th and 15th centuries, Fair Isle was a Norwegian possession. In 1469, Shetland, along with Orkney, was part of the dowry of the King of Denmark's daughter, Margaret, on her marriage to James III of Scotland.

On 20 August 1588 the flagship of the Spanish Armada, El Gran Grifón, was shipwrecked in the cove of Stroms Hellier, forcing its 300 sailors to spend six weeks living with the islanders. The wreck was discovered in 1970. The large Canadian sailing ship Black Watch was wrecked on Fair Isle in 1877.

In 1862 around 40% of the population migrated to New Brunswick.

Fair Isle was bought by the National Trust for Scotland in 1954 from George Waterston, the founder of the bird observatory. In that decade, electricity was not yet available to residents and only some homes had running water; the population was declining at a level that created concern.

The population decreased steadily from about 400 in 1900. There were around 55 permanent residents on the island in 2015, the majority of whom were crofters. In April 2021, the population was 48 and the island became the first place in the UK all of whose adult inhabitants had been vaccinated against COVID-19. The island has 14 scheduled monuments, ranging from the earliest signs of human activity to the remains of a Second World War radar station. The two automated lighthouses are protected as listed buildings.

The island houses a series of high-technology relay stations carrying vital TV, radio, telephone and military communication links between Shetland, Orkney and the Scottish mainland. In this respect it continues its historic role as a signal station, linking the mainland and the more remote island groups. In 1976, when television relay equipment was updated to permit colour broadcasts to Shetland, the new equipment was housed in former Second World War radar station buildings on Fair Isle. Many television signals are relayed from Orkney to Shetland (rather than from the Scottish mainland) via Orkney's Keelylang Hill transmitter station.

Wartime military role
During the Second World War, the Royal Navy built two radar stations on top of Ward Hill (712 ft), which operated from February and March 1940 and played an important role in detecting German bombers approaching Scapa Flow on 8 and 10 April 1940. The ruined buildings and Nissen huts are still present. A cable-operated narrow gauge railway lies disused, though it was once used to send supplies up to the summit of Ward Hill.

On 17 January 1941, a German Heinkel He 111 bomber, modified as a meteorological aircraft, crashed on the island; wreckage remains on the crash-site to the present day. The aircraft had been flying on a routine weather reconnaissance flight from its base at Oldenburg in Germany. It was intercepted by RAF Hawker Hurricane fighters from 3 Squadron, based at RAF Sumburgh; both of the aircraft's engines were damaged and several of the five crew were wounded. The pilot managed to make a crash-landing on Fair Isle to avoid ditching his crippled aircraft in the sea. Two crew died and three survived. The dead crew were buried in the island's churchyard; the survivors were detained by the islanders and remained for several days until weather conditions allowed them to be taken off the island by means of the Lerwick Lifeboat. Before the Lerwick boat reached the island, two separate boats from Orkney ran aground whilst making their way to collect the prisoners of war.

The South Light was a target. During raids, the wife of an assistant keeper was killed in 1941 and their daughter was injured; in 1942, the wife of another keeper and their daughter also died in a raid.

On 22 July 1941, Spitfire X5401 piloted by Flying Officer M. D. S. Hood crash-landed on Fair Isle returning from a reconnaissance mission over Ålesund, Norway. The pilot recalled the crash site to be adjacent to the track which crossed the airstrip. The cause of the crash proved to be a leak of coolant, which resulted in the engine overheating. The aircraft was recovered and flew again, and the pilot survived the war.

Geography

Fair Isle is administratively part of the parish of Dunrossness, Shetland, and is roughly equidistant from Sumburgh Head, some 38 km to the northeast on the Mainland of Shetland and North Ronaldsay, Orkney, some 43 km to the southwest. Fair Isle is 4.8 km long and 2.4 km wide. It has an area of 8 km2, making it the tenth-largest of the Shetland Islands. It gives its name to one of the British Sea Areas.

Most of the islanders live in the crofts on the southern half of the island, the northern half consisting of rocky moorland. The western coast consists of cliffs of up to 200 m in height, Ward Hill at 217 m being the highest point of the island and its only Marilyn. On the eastern coast the almost detached headland of Sheep Rock rises to 132 m.

Climate
Fair Isle experiences an oceanic climate (Köppen Cfb), bordering on a subpolar oceanic climate (Cfc), with cool summers and mild winters. This is especially pronounced because of its location far from any sizeable landmass; Fair Isle has the smallest overall temperature range (least continental) of any weather station in the British Isles: a maximum of 22.6 C and a minimum of -5.6 C since 1951. This 60+ year temperature span is actually smaller than many places in inland southern England will record within a given three-month period. To further illustrate how extreme the maritime moderation at Fair Isle is, a rural location near the coastline in Northern Stockholm County on a similar latitude in Sweden broke Fair Isle's then all-time records in both directions within a 48-hour period between 26 and 28 April 2014.

On 19 July 2022, a maximum temperature of 22.6 °C was registered in Fair Isle.

The lowest temperature recorded in recent years was -4.6 C in February 2010. Rainfall, at under 1000 mm, is lower than one might expect for somewhere often in the main path of Atlantic depressions. This is explained by a lack of heavy convective rainfall during spring and summer months due to the absence of warm surface conditions.

Fair Isle's ocean moderation is so strong that areas on the same latitudes in the Scandinavian inland less than 1000 km to the east have average summer highs 2 - 3 C-change higher than Fair Isle's all-time record temperature, for example the Norwegian capital of Oslo and the Swedish capital of Stockholm. The -5 C all-time low is uniquely mild for European locations on the 59th parallel north. The winter daily means are comparable to many areas as far south in the British Isles as south-central England, because of the extreme maritime moderation. It is in hardiness zone 9b or 10a (compared to 8b for the Faroes, 7b or 8a for Stockholm, and 1b for parts of Canada, all on or near the 60th parallel north. Central Florida (at 27-8 degrees north) has this hardiness zone.

Economy
Over the centuries the island has changed hands many times. Trading links with Northern Europe are reflected in Fair Isle Haa, a traditional Hanseatic trading booth located not far from the South Harbour, traditionally used by residents of the southern part of the island. Rent was usually paid to absentee landlords (who rarely visited) in butter, cloth and fish oil.

Fishing has always been an important industry for the island. In 1702, the Dutch, who were interested in Shetland's herring fisheries, fought a naval battle against French warships just off the island.

Fair Isle is noted for its woollen jumpers, with knitting forming an important source of income for the women of the islands. The principal activity for the male islanders is crofting.

In January 2004, Fair Isle was granted Fairtrade Island status.

Bird life
Many rare species of bird have been found on the island, with at least 27 species found on the island that were the first British records, and is probably the best place in western Europe to see skulking Siberian passerines such as Pechora pipit, lanceolated warbler and Pallas's grasshopper warbler. For example, in 2015, rare birds discovered on the island included pallid harrier, arctic warbler, Moltoni's warbler, booted warbler, paddyfield warbler, siberian thrush, and thrush nightingale.

The island is also home to an endemic subspecies of Eurasian wren, the Fair Isle wren Troglodytes troglodytes fridariensis.

Bird observatory
In 1948, George Waterston founded a permanent bird observatory on the island. Because of its importance as a bird migration watchpoint, it provided most of the accommodation on the island. The first director of the observatory was Kenneth Williamson. It was unusual amongst bird observatories in providing catered, rather than hostel-style, accommodation.

In 2010, a new observatory was built: a wooden lodge of two storeys, which cost £4 million and accommodated around 30 guests. The 2010 observatory building was destroyed by fire on 10 March 2019; the observatory's records had been digitised and were not affected. The cost of rebuilding was estimated at £7.4m.

Infrastructure

Other than the restaurant of the bird observatory, and its small evening-only bar, there are no pubs or restaurants on the island. There is one shop, one school and a community hall used for meetings and social events. There is no police station on the island; the main station is Lerwick and a section station is located in the village of Brae.

Passenger service to the island is provided by SIC Ferries on the vessel Good Shepherd IV or by a nine-seat passenger aeroplane from Tingwall Airport near Lerwick, operated by regional carrier Directflight.

Electricity supply
Fair Isle is not connected to the National Grid; electricity is provided by the Fair Isle Electricity Company. From the 1980s, power was generated by two diesel generators and two wind turbines. Diesel generators were automatically switched off if wind turbines provided sufficient power. Excess capacity was distributed through a separate network for home heating, with remote frequency-sensitive programmable relays controlling water heaters and storage heaters in the buildings of the community. Following the installation of three wind turbines, combined with solar panels and batteries, in a £3.5 million scheme completed in October 2018, the island has had a 24-hour electricity supply.

Communication
Fair Isle is home to two GSM 900 MHz base stations operated by Vodafone and O2. On 16 April 2019, an EE 4G antenna was turned on by Openreach. In 2023, the island became connected by a fibre submarine cable, as a spur off a cable linking Shetland and Orkney. This supplements and upgrades the long distance microwave link opened in 1979. Full fibre services then became available to all properties on the island.

Emergency services
Fair Isle has a fire station equipped with a single fire appliance, and staffed by a retained fire crew of local volunteers. It was originally part of the Highlands and Islands Fire and Rescue Service, which was absorbed into the national Scottish Fire and Rescue Service on 1 April 2013. A locally organised volunteer fire brigade was formed in 1996 by island residents. This was later absorbed into the statutory fire service, with professional training provided, and the local service designated a retained fire crew. The first purpose-built fire engine was stationed to the island in 2002.

In October 2011, a contract for the construction of a £140,000 purpose-built fire station was awarded to Shetland company Ness Engineering, who completed the construction and equipping of the fire station, including its connection to the island power and water supplies, and the installation of a rainwater harvesting system within the building. The new fire station was officially opened on 14 March 2013.

There is a small Coastguard cliff-rescue team on the island. Like the fire service, the Coastguard is a retained (volunteer) emergency service. The Fair Isle Coastguard cliff rescue team were the first British Coastguard unit to be equipped with a quad ATV. The quad is painted in HM Coastguard livery, with reflective Battenburg markings and has an optional equipment trailer.

There are no emergency medical services on Fair Isle. Routine medical care is provided by a community nurse. In the event of accident and emergency the community nurse provides first aid until casualties can be removed to Shetland Mainland, usually by helicopter air ambulance. In severe weather conditions or life-threatening emergencies, the Coastguard helicopter can undertake the patient evacuation.

Air

Fair Isle Airport serves the island with flights to Tingwall Airport near Lerwick, and weekly to Sumburgh Airport, both on Shetland Mainland. Flights to Kirkwall on Orkney were scheduled to begin in September 2017, provided by Loganair. Private aircraft use the facility and scheduled flights arrive twice daily, three days a week. There is a small terminal building providing limited services. Fire cover is provided by the island fire service.

There are two helipads on the island; one at the South Fair Isle lighthouse and used by Northern Lighthouse Board and HM Coastguard helicopters, and the other at the North Fair Isle lighthouse.

Sea
There are two main harbours, north harbour and south harbour; both formed naturally, being sheltered by the headland of Bu Ness. They are separated by a narrow isthmus of gravel. The north harbour is the main route for goods, provisions, and Royal Mail postal services arriving at and departing from the island. The ferry Good Shepherd IV plies between Fair Isle north harbour and Grutness on Shetland Mainland. In summer only, the ferry also runs from Lerwick once every two weeks.

Road
A road connects the populated areas of the island, along its full length.

Education
Fair Isle has one primary school, with two classrooms. There is a full-time head teacher, and a part-time assistant teacher. The number of pupils varies over time, but has generally been between five and ten, with three pupils as of 2021. Islanders of secondary school age are generally educated off-island, on Shetland Mainland, where they board in halls of residence, returning to Fair Isle during holiday periods.

Religion
Christianity is the only formally organised religion on Fair Isle. There are two churches, one Methodist, and one Church of Scotland (Presbyterian). The Methodist Church has a resident non-stipendiary minister, who reports to a full-time minister on Shetland Mainland. The Methodist Church was constructed in 1886.

The Church of Scotland church was built in 1892. The Church of Scotland parish which contains Fair Isle is Dunrossness, which is linked with Sandwick, Cunningsburgh and Quarff parishes. The congregation's minister is Reverend Charles H. Greig.

Conservation designations
Most of the island is designated by NatureScot as both a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SCA). The island and its surrounding seas are also designated by NatureScot as a Special Protection Area (SPA) due to the important bird species present.

In 2016 the seas around Fair Isle were designated as a Marine Protected Area (MPA). As of 2019 it is the only MPA in Scotland to be designated specifically as a "Demonstration and Research" MPA. The aims of this MPA designation are defined as being: To demonstrate and research the use of an ecosystem approach, which includes the following - a) the environmental monitoring of seabirds and of other mobile marine species; b) the environmental monitoring of the factors which influence the populations of seabirds and of other mobile species; c) the development and implementation of a local sustainable shellfish fishery; d) the development of a research programme into local fisheries which includes research on species composition, size, distribution and temporal and spatial changes in fish stocks; e) based upon the research undertaken under sub-paragraph (d), the development of a sustainable-use management programme for local fisheries.

— Scottish Government

Notable people

 * Ewen Thomson (born 1971 in Fair Isle), a Scottish luthier, specialising in violins, violas and cellos
 * Inge Thomson (born 1974 in Fair Isle), a singer and multi instrumentalist
 * Chris Stout (born 1976), a Scottish fiddle/violin player from Shetland; grew up in Fair Isle

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Four Feather Falls

Four Feather Falls is a British children's western television series, the third puppet TV show produced by AP Films (APF) in association with Granada Television. It was based on an idea by Barry Gray, who also wrote the show's music. The series was the first to use an early version of APF's Supermarionation puppetry. Thirty-nine 13-minute episodes were produced between April 1959 and April 1960, and the series was first broadcast on the ITV network from February to November 1960.

The setting is the late 19th-century fictional Kansas town of Four Feather Falls, where the hero of the series, Tex Tucker, is a sheriff. The four feathers of the title refers to four magical feathers given to Tex by the Indian chief Kalamakooya as a reward for saving his grandson. One of the feathers allowed Tex's guns to swivel and fire without being touched whenever he was in danger, two conferred the power of speech on Tex's horse and dog, and the fourth feather could summon Kalamakooya.

Tex's speaking voice was provided by Nicholas Parsons, and his singing voice by Michael Holliday. The series was sporadically repeated on British television until 1968, and was released on DVD in 2005.

Plot
The series is set in the fictitious late 19th-century Western town of Four Feather Falls, Kansas, and features the adventures of its sheriff, Tex Tucker.

In the first episode, Grandpa Twink relates the story of how it all began to his grandson, Little Jake. Tex is riding up from the valley and comes across a lost and hungry Indian boy, Makooya, and saves him. Tex is given four magic feathers by the boy's grandfather, Chief Kalamakooya, as a reward for saving his grandson. Two of the feathers allow his guns to swivel and fire automatically (often while Tex's hands are raised), and the other two allow his horse, Rocky, and his dog, Dusty, to speak. As Tex, his horse, and dog are very thirsty, Kalamakooya also makes a waterfall where there had been no water before, and so when the town was built it was named after Tex's feathers and the waterfall.

The characters of the town are Grandpa Twink, who does little but rest in a chair; his grandson Little Jake, the only child in town; Ma Jones, who runs the town store; Doc Haggerty; Slim Jim, the bartender of the Denison saloon; Marvin Jackson, the bank manager; and Dan Morse, the telegraphist. Other characters appeared from time to time for only one episode, often just visiting town.

The villains included Pedro, who was introduced in the first show and Fernando, who first appeared in the second episode as a sidekick and someone Pedro could blame when things went wrong, as they always did. Big Ben was another villain who appeared from time to time, as did Red Scalp, a renegade Indian. Other villains only appeared in single episodes.

Cast

 * Nicholas Parsons – Sheriff Tex Tucker (speaking voice) / Telegraph Operator Dan Morse / Various
 * Michael Holliday – Sheriff Tex Tucker (singing voice) / Various
 * Kenneth Connor – Dusty the Dog / Rocky the Horse / Pedro the Bandit / Big Chief Kalamakooya / Bank Manager Marvin Jackson / Doc Haggerty / Saloon Owner Slim Jim Denison / Various
 * David Graham – Grandpa Ebenezer Twink / Fernando the Bandit / Big Ben the Horse Rustler Bandit / Red Scalp the Renegade Indian / Various
 * Denise Bryer – Martha "Ma" Jones / Little Jake / Makooya the Little Indian Boy / Various

Denise Bryer had worked with Anderson on The Adventures of Twizzle, and he wanted her to play some of the voices in Four Feather Falls. Anderson visited Bryer at her home with some scripts and asked her husband, Nicholas Parsons, to help by reading some of the other parts, including the sheriff Tex Tucker. Anderson liked Parsons' interpretation and offered him the job of providing Tex's speaking voice.

Production
American Western TV shows such as Gunsmoke and Wagon Train were popular with British audiences, so APF's Gerry Anderson and Arthur Provis decided to make a cowboy series based on a story concept pitched to them by Barry Gray. According to Anderson, Four Feather Falls "was really me trying to make the sort of films I used to see in the cinema." APF offered Gray about £100 (£ in ) to buy his idea, which was originally titled Two Gun Tex Tucker. This was changed to Two Gun Tex of Texas, then The Sheriff of Four Feather Falls before the final title was chosen.

Development began in late 1958 while the first 26 episodes of Torchy the Battery Boy were still in production, and without the knowledge of APF's employer Roberta Leigh, with whom Anderson planned to sever ties in the aim of becoming an independent producer. The pilot episode, "How It Began", was produced in April 1959 on a budget of £6,000 (about £ in ). A full series of 39 episodes was commissioned by Granada after APF's intended distributor, Anglo Amalgamated, turned it down. Except for the pilot, which was made in APF's studios at Islet Park House in Maidenhead, all episodes were made in a converted warehouse on the Slough Trading Estate. Previously owned by special effects artist Les Bowie, this provided quadruple the floor space of Islet Park House, where the crew had been filming in a re-purposed ballroom. After moving to the Slough estate in June 1959, APF upgraded its new facilities with the installation of a director's control booth and video assist TV monitors to guide the puppeteers, who operated the marionettes from a Dexion bridge built several feet over the set. The model set representing the town of Four Feather Falls measured 30 x 15 ft. Filming in Slough ended in April 1960.

Anderson considered the puppets with static heads, made by Christine Glanville for his earlier productions, to be unacceptable because the viewer could not tell which character was talking unless its puppet moved up or down. For Four Feather Falls, the papier-mâché heads were replaced by interchangeable hollow fibreglass heads with internal rods that could move the eyes from side to side. The heads also contained sound-activated solenoids, which allowed the puppets' lips to move automatically in synchronisation with the dialogue. The electronics of the day required more space than would be available in a human-scale head, therefore all the puppets in Four Feather Falls had oversized heads, though the bodies as a whole were one-third life size. Anderson's aim was to make the puppets look as realistic as possible, the beginning of the Supermarionation puppetry process, although that term was not coined until his next series, Supercar.

The wires used to control the puppets were eight feet long and made of tungsten steel, an improvement on the curtain wire used in Anderson's two earlier puppet series (The Adventures of Twizzle and Torchy), and were only 1/200 of an inch thick. Being shiny, the wires had to be blackened. The horses moved by being pulled along on a trolley, which meant the viewer never saw their feet when they were moving.

The voice cast assembled to record each script without seeing the puppets, much like recording a radio series; synchronisation of each character's speech with the movement of its puppet's mouth was performed later. The tight budget precluded the use of sophisticated special effects, and less costly alternatives were used. For example, to achieve the effect of muzzle flashes, small specks of black paint were carefully applied to the 35 mm negatives so they would appear as white flashes on the finished prints. The production design and puppet costuming were more detailed than those of Twizzle and Torchy.

Continuity for the series was provided by Sylvia Thamm, who later married Gerry Anderson. Provis, who left APF mid-production due to disagreements over the direction of the company, was given a five per cent share of the profits from the series.

Music
The show's music and song lyrics were composed by Barry Gray. Michael Holliday provided Tex's singing voice, and Tommy Reilly performed the harmonica pieces. The best known song to come out of the series was "Four Feather Falls", sung in some episodes by Michael Holliday in the style of Bing Crosby and sometimes incorrectly described as the theme song to the series. The closing theme song was "Two Gun Tex of Texas." Holliday was paid £2,000 (about £ in ) for his singing work on the pilot episode – a significant part of the pilot's £6,000 budget. In all, Holliday recorded six songs for the series: "Four Feather Falls", "The Phantom Rider", "The Rick-Rick-A-Rackety Train", "Happy Hearts and Friendly Faces", "My Home Town", and "Two Gun Tex of Texas". The recording was conducted at Gate Studios in Borehamwood.

Syndication
Four Feather Falls was the first APF series to be fully networked on ITV, that is shown by all regional franchises of the network simultaneously. The series was repeated in some British TV regions on a sporadic basis up until 1968. In December 2004, it was announced that the rights had been acquired by Network, and it was released on three Region 2 DVDs in May 2005. It is the only Supermarionation series not yet released to DVD in North America as of January 2006. Sylvia Anderson wrote two British children's annuals based on the show, published by Collins in 1960 and 1961. The first book featured a short text story based on the pilot episode of the TV series.

Other media
The show was adapted into comics form and published as an ongoing strip in Polystyle Publications' TV Comic. The Four Feathers Falls strip was drawn by Neville Main, and appeared from issue #439 (14 May 1960) until issue #564 (6 October 1962). Sylvia Anderson wrote a Four Feather Falls annual. A tie-in board game was also released.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Four Feather Falls


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Talk:Free State Danzig

''Doesn't this belong under Gdansk? And a lot of the below sounds anti-Polish, and suffers from an excessive use of German.''

I suggest removing this page, almost all information it contains is also on Gdansk, and it was Free City not Free State anyway --Taw
 * The useful stuff needs to go under Gdansk,the rest just needs to go. JHK

This is a good example of where redirects don't work; if I hit the topic of "Free State Danzig", I end up in an article where the explanation of the term "Free State of Danzig" is waaaaaaay down the page. In fact the term "Free State" doesn't even appear in the article it's redirected to, only the German is given. This is bad. What we want is a little stub which quickly explains the history of the "Free State of Danzig" name (this history can be found in the Gdansk article), and then a suggestion to look in Gdansk for more information. GregLindahl

title: Talk:Free State Danzig


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Fly-by-wire

Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires, and flight control computers determine how to move the actuators at each control surface to provide the ordered response. Implementations either use mechanical flight control backup systems or else are fully electronic.

Improved fully fly-by-wire systems interpret the pilot's control inputs as a desired outcome and calculate the control surface positions required to achieve that outcome; this results in various combinations of rudder, elevator, aileron, flaps and engine controls in different situations using a closed feedback loop. The pilot may not be fully aware of all the control outputs acting to affect the outcome, only that the aircraft is reacting as expected. The fly-by-wire computers act to stabilize the aircraft and adjust the flying characteristics without the pilot's involvement, and to prevent the pilot from operating outside of the aircraft's safe performance envelope.

Rationale
Mechanical and hydro-mechanical flight control systems are relatively heavy and require careful routing of flight control cables through the aircraft by systems of pulleys, cranks, tension cables and hydraulic pipes. Both systems often require redundant backup to deal with failures, which increases weight. Both have limited ability to compensate for changing aerodynamic conditions. Dangerous characteristics such as stalling, spinning and pilot-induced oscillation (PIO), which depend mainly on the stability and structure of the aircraft concerned rather than the control system itself, are dependent on the pilot's actions.

The term "fly-by-wire" implies a purely electrically signaled control system. It is used in the general sense of computer-configured controls, where a computer system is interposed between the operator and the final control actuators or surfaces. This modifies the manual inputs of the pilot in accordance with control parameters.

Side-sticks or conventional flight control yokes can be used to fly FBW aircraft.

Weight saving
A FBW aircraft can be lighter than a similar design with conventional controls. This is partly due to the lower overall weight of the system components and partly because the natural stability of the aircraft can be relaxed (slightly for a transport aircraft; more for a maneuverable fighter), which means that the stability surfaces that are part of the aircraft structure can therefore be made smaller. These include the vertical and horizontal stabilizers (fin and tailplane) that are (normally) at the rear of the fuselage. If these structures can be reduced in size, airframe weight is reduced. The advantages of FBW controls were first exploited by the military and then in the commercial airline market. The Airbus series of airliners used full-authority FBW controls beginning with their A320 series, see A320 flight control (though some limited FBW functions existed on A310). Boeing followed with their 777 and later designs.

Closed-loop feedback control

A pilot commands the flight control computer to make the aircraft perform a certain action, such as pitch the aircraft up, or roll to one side, by moving the control column or sidestick. The flight control computer then calculates what control surface movements will cause the plane to perform that action and issues those commands to the electronic controllers for each surface. The controllers at each surface receive these commands and then move actuators attached to the control surface until it has moved to where the flight control computer commanded it to. The controllers measure the position of the flight control surface with sensors such as LVDTs.

Automatic stability systems
Fly-by-wire control systems allow aircraft computers to perform tasks without pilot input. Automatic stability systems operate in this way. Gyroscopes and sensors such as accelerometers are mounted in an aircraft to sense rotation on the pitch, roll and yaw axes. Any movement (from straight and level flight for example) results in signals to the computer, which can automatically move control actuators to stabilize the aircraft.

Safety and redundancy
While traditional mechanical or hydraulic control systems usually fail gradually, the loss of all flight control computers immediately renders the aircraft uncontrollable. For this reason, most fly-by-wire systems incorporate either redundant computers (triplex, quadruplex etc.), some kind of mechanical or hydraulic backup or a combination of both. A "mixed" control system with mechanical backup feedbacks any rudder elevation directly to the pilot and therefore makes closed loop (feedback) systems senseless.

Aircraft systems may be quadruplexed (four independent channels) to prevent loss of signals in the case of failure of one or even two channels. High performance aircraft that have fly-by-wire controls (also called CCVs or Control-Configured Vehicles) may be deliberately designed to have low or even negative stability in some flight regimes – rapid-reacting CCV controls can electronically stabilize the lack of natural stability.

Pre-flight safety checks of a fly-by-wire system are often performed using built-in test equipment (BITE). A number of control movement steps can be automatically performed, reducing workload of the pilot or groundcrew and speeding up flight-checks.

Some aircraft, the Panavia Tornado for example, retain a very basic hydro-mechanical backup system for limited flight control capability on losing electrical power; in the case of the Tornado this allows rudimentary control of the stabilators only for pitch and roll axis movements.

History

Servo-electrically operated control surfaces were first tested in the 1930s on the Soviet Tupolev ANT-20. Long runs of mechanical and hydraulic connections were replaced with wires and electric servos.

In 1934, Karl Otto Altvater filed a patent about the automatic-electronic system, which flared the aircraft, when it was close to the ground.

In 1941, Karl Otto Altvater, who was an engineer at Siemens, developed and tested the first fly-by-wire system for the Heinkel He 111, in which the aircraft was fully controlled by electronic impulses.

The first non-experimental aircraft that was designed and flown (in 1958) with a fly-by-wire flight control system was the Avro Canada CF-105 Arrow, a feat not repeated with a production aircraft (though the Arrow was cancelled with five built) until Concorde in 1969, which became the first fly-by-wire airliner. This system also included solid-state components and system redundancy, was designed to be integrated with a computerised navigation and automatic search and track radar, was flyable from ground control with data uplink and downlink, and provided artificial feel (feedback) to the pilot.

The first electronic fly-by-wire testbed operated by the U.S. Air Force was a Boeing B-47E Stratojet (Ser. No. 53-2280)

The first pure electronic fly-by-wire aircraft with no mechanical or hydraulic backup was the Apollo Lunar Landing Training Vehicle (LLTV), first flown in 1968. This was preceded in 1964 by the Lunar Landing Research Vehicle (LLRV) which pioneered fly-by-wire flight with no mechanical backup. Control was through a digital computer with three analog redundant channels. In the USSR, the Sukhoi T-4 also flew. At about the same time in the United Kingdom a trainer variant of the British Hawker Hunter fighter was modified at the British Royal Aircraft Establishment with fly-by-wire flight controls for the right-seat pilot.

In the UK the two seater Avro 707C was flown with a Fairey system with mechanical backup in the early to mid-60s. The program was curtailed when the air-frame ran out of flight time.

In 1972, the first digital fly-by-wire fixed-wing aircraft without a mechanical backup to take to the air was an F-8 Crusader, which had been modified electronically by NASA of the United States as a test aircraft; the F-8 used the Apollo guidance, navigation and control hardware.

The Airbus A320 began service in 1988 as the first airliner with digital fly-by-wire controls.

Boeing chose fly-by-wire flight controls for the 777 in 1994, departing from traditional cable and pulley systems. In addition to overseeing the aircraft's flight control, the FBW offered "envelope protection", which guaranteed that the system would step in to avoid accidental mishandling, stalls, or excessive structural stress on the aircraft. 777 used ARINC 629 buses to connect primary flight computers (PFCs) with actuator-control electronics units (ACEs). Every PFC housed three 32-bit microprocessors, including a Motorola 68040, an Intel 80486, and an AMD 29050, all programmed in Ada programming language.

Analog systems
All "fly-by-wire" flight control systems eliminate the complexity, the fragility and the weight of the mechanical circuit of the hydromechanical or electromechanical flight control systems – each being replaced with electronic circuits. The control mechanisms in the cockpit now operate signal transducers, which in turn generate the appropriate electronic commands. These are next processed by an electronic controller—either an analog one, or (more modernly) a digital one. Aircraft and spacecraft autopilots are now part of the electronic controller.

The hydraulic circuits are similar except that mechanical servo valves are replaced with electrically controlled servo valves, operated by the electronic controller. This is the simplest and earliest configuration of an analog fly-by-wire flight control system. In this configuration, the flight control systems must simulate "feel". The electronic controller controls electrical feel devices that provide the appropriate "feel" forces on the manual controls. This was used in Concorde, the first production fly-by-wire airliner.

Digital systems

A digital fly-by-wire flight control system can be extended from its analog counterpart. Digital signal processing can receive and interpret input from multiple sensors simultaneously (such as the altimeters and the pitot tubes) and adjust the controls in real time. The computers sense position and force inputs from pilot controls and aircraft sensors. They then solve differential equations related to the aircraft's equations of motion to determine the appropriate command signals for the flight controls to execute the intentions of the pilot.

The programming of the digital computers enable flight envelope protection. These protections are tailored to an aircraft's handling characteristics to stay within aerodynamic and structural limitations of the aircraft. For example, the computer in flight envelope protection mode can try to prevent the aircraft from being handled dangerously by preventing pilots from exceeding preset limits on the aircraft's flight-control envelope, such as those that prevent stalls and spins, and which limit airspeeds and g forces on the airplane. Software can also be included that stabilize the flight-control inputs to avoid pilot-induced oscillations.

Since the flight-control computers continuously feedback the environment, pilot's workloads can be reduced. This also enables military aircraft with relaxed stability. The primary benefit for such aircraft is more maneuverability during combat and training flights, and the so-called "carefree handling" because stalling, spinning and other undesirable performances are prevented automatically by the computers. Digital flight control systems (DFCS) enable inherently unstable combat aircraft, such as the Lockheed F-117 Nighthawk and the Northrop Grumman B-2 Spirit flying wing to fly in usable and safe manners.

Legislation
The Federal Aviation Administration (FAA) of the United States has adopted the RTCA/DO-178C, titled "Software Considerations in Airborne Systems and Equipment Certification", as the certification standard for aviation software. Any safety-critical component in a digital fly-by-wire system including applications of the laws of aeronautics and computer operating systems will need to be certified to DO-178C Level A or B, depending on the class of aircraft, which is applicable for preventing potential catastrophic failures.

Nevertheless, the top concern for computerized, digital, fly-by-wire systems is reliability, even more so than for analog electronic control systems. This is because the digital computers that are running software are often the only control path between the pilot and aircraft's flight control surfaces. If the computer software crashes for any reason, the pilot may be unable to control an aircraft. Hence virtually all fly-by-wire flight control systems are either triply or quadruply redundant in their computers and electronics. These have three or four flight-control computers operating in parallel and three or four separate data buses connecting them with each control surface.

Redundancy
The multiple redundant flight control computers continuously monitor each other's output. If one computer begins to give aberrant results for any reason, potentially including software or hardware failures or flawed input data, then the combined system is designed to exclude the results from that computer in deciding the appropriate actions for the flight controls. Depending on specific system details there may be the potential to reboot an aberrant flight control computer, or to reincorporate its inputs if they return to agreement. Complex logic exists to deal with multiple failures, which may prompt the system to revert to simpler back-up modes.

In addition, most of the early digital fly-by-wire aircraft also had an analog electrical, mechanical, or hydraulic back-up flight control system. The Space Shuttle had, in addition to its redundant set of four digital computers running its primary flight-control software, a fifth back-up computer running a separately developed, reduced-function, software flight-control system – one that could be commanded to take over in the event that a fault ever affected all of the computers in the other four. This back-up system served to reduce the risk of total flight-control-system failure ever happening because of a general-purpose flight software fault that had escaped notice in the other four computers.

Efficiency of flight
For airliners, flight-control redundancy improves their safety, but fly-by-wire control systems, which are physically lighter and have lower maintenance demands than conventional controls also improve economy, both in terms of cost of ownership and for in-flight economy. In certain designs with limited relaxed stability in the pitch axis, for example the Boeing 777, the flight control system may allow the aircraft to fly at a more aerodynamically efficient angle of attack than a conventionally stable design. Modern airliners also commonly feature computerized Full-Authority Digital Engine Control systems (FADECs) that control their jet engines, air inlets, fuel storage and distribution system, in a similar fashion to the way that FBW controls the flight control surfaces. This allows the engine output to be continually varied for the most efficient usage possible.

The second generation Embraer E-Jet family gained a 1.5% efficiency improvement over the first generation from the fly-by-wire system, which enabled a reduction from 280 ft.² to 250 ft.² for the horizontal stabilizer on the E190/195 variants.

Airbus/Boeing
Airbus and Boeing differ in their approaches to implementing fly-by-wire systems in commercial aircraft. Since the Airbus A320, Airbus flight-envelope control systems always retain ultimate flight control when flying under normal law and will not permit the pilots to violate aircraft performance limits unless they choose to fly under alternate law. This strategy has been continued on subsequent Airbus airliners. However, in the event of multiple failures of redundant computers, the A320 does have a mechanical back-up system for its pitch trim and its rudder, the Airbus A340 has a purely electrical (not electronic) back-up rudder control system and beginning with the A380, all flight-control systems have back-up systems that are purely electrical through the use of a "three-axis Backup Control Module" (BCM).

Boeing airliners, such as the Boeing 777, allow the pilots to completely override the computerised flight-control system, permitting the aircraft to be flown outside of its usual flight-control envelope.

Applications

 * Concorde was the first production fly-by-wire aircraft with analogue control.
 * The General Dynamics F-16 was the first production aircraft to use digital fly-by-wire controls.
 * The Space Shuttle orbiter had an all-digital fly-by-wire control system. This system was first exercised (as the only flight control system) during the glider unpowered-flight "Approach and Landing Tests" that began on the Space Shuttle Enterprise during 1977.
 * Launched into production during 1984, the Airbus Industries Airbus A320 became the first airliner to fly with an all-digital fly-by-wire control system.
 * With its launch in 1993 the Boeing C-17 Globemaster III became the first fly-by-wire military transport aircraft.
 * In 2005, the Dassault Falcon 7X became the first business jet with fly-by-wire controls.
 * A fully digital fly-by-wire without a closed feedback loop was integrated 2002 in the first generation Embraer E-Jet family. By closing the loop (feedback), the second generation Embraer E-Jet family gained a 1.5% efficiency improvement in 2016.

Engine digital control
The advent of FADEC (Full Authority Digital Engine Control) engines permits operation of the flight control systems and autothrottles for the engines to be fully integrated. On modern military aircraft other systems such as autostabilization, navigation, radar and weapons system are all integrated with the flight control systems. FADEC allows maximum performance to be extracted from the aircraft without fear of engine misoperation, aircraft damage or high pilot workloads.

In the civil field, the integration increases flight safety and economy. Airbus fly-by-wire aircraft are protected from dangerous situations such as low-speed stall or overstressing by flight envelope protection. As a result, in such conditions, the flight control systems commands the engines to increase thrust without pilot intervention. In economy cruise modes, the flight control systems adjust the throttles and fuel tank selections precisely. FADEC reduces rudder drag needed to compensate for sideways flight from unbalanced engine thrust. On the A330/A340 family, fuel is transferred between the main (wing and center fuselage) tanks and a fuel tank in the horizontal stabilizer, to optimize the aircraft's center of gravity during cruise flight. The fuel management controls keep the aircraft's center of gravity accurately trimmed with fuel weight, rather than drag-inducing aerodynamic trims in the elevators.

Fly-by-optics

Fly-by-optics is sometimes used instead of fly-by-wire because it offers a higher data transfer rate, immunity to electromagnetic interference and lighter weight. In most cases, the cables are just changed from electrical to optical fiber cables. Sometimes it is referred to as "fly-by-light" due to its use of fiber optics. The data generated by the software and interpreted by the controller remain the same. Fly-by-light has the effect of decreasing electro-magnetic disturbances to sensors in comparison to more common fly-by-wire control systems. The Kawasaki P-1 is the first production aircraft in the world to be equipped with such a flight control system.

Power-by-wire
Having eliminated the mechanical transmission circuits in fly-by-wire flight control systems, the next step is to eliminate the bulky and heavy hydraulic circuits. The hydraulic circuit is replaced by an electrical power circuit. The power circuits power electrical or self-contained electrohydraulic actuators that are controlled by the digital flight control computers. All benefits of digital fly-by-wire are retained since the power-by-wire components are strictly complementary to the fly-by-wire components.

The biggest benefits are weight savings, the possibility of redundant power circuits and tighter integration between the aircraft flight control systems and its avionics systems. The absence of hydraulics greatly reduces maintenance costs. This system is used in the Lockheed Martin F-35 Lightning II and in Airbus A380 backup flight controls. The Boeing 787 and Airbus A350 also incorporate electrically powered backup flight controls which remain operational even in the event of a total loss of hydraulic power.

Fly-by-wireless
Wiring adds a considerable amount of weight to an aircraft; therefore, researchers are exploring implementing fly-by-wireless solutions. Fly-by-wireless systems are very similar to fly-by-wire systems, however, instead of using a wired protocol for the physical layer a wireless protocol is employed.

In addition to reducing weight, implementing a wireless solution has the potential to reduce costs throughout an aircraft's life cycle. For example, many key failure points associated with wire and connectors will be eliminated thus hours spent troubleshooting wires and connectors will be reduced. Furthermore, engineering costs could potentially decrease because less time would be spent on designing wiring installations, late changes in an aircraft's design would be easier to manage, etc.

Intelligent flight control system
A newer flight control system, called intelligent flight control system (IFCS), is an extension of modern digital fly-by-wire flight control systems. The aim is to intelligently compensate for aircraft damage and failure during flight, such as automatically using engine thrust and other avionics to compensate for severe failures such as loss of hydraulics, loss of rudder, loss of ailerons, loss of an engine, etc. Several demonstrations were made on a flight simulator where a Cessna-trained small-aircraft pilot successfully landed a heavily damaged full-size concept jet, without prior experience with large-body jet aircraft. This development is being spearheaded by NASA Dryden Flight Research Center. It is reported that enhancements are mostly software upgrades to existing fully computerized digital fly-by-wire flight control systems. The Dassault Falcon 7X and Embraer Legacy 500 business jets have flight computers that can partially compensate for engine-out scenarios by adjusting thrust levels and control inputs, but still require pilots to respond appropriately.

title: Fly-by-wire