A Sector clock or colour change clock was a round colour-coded clock used at military airfields and observation posts in the United Kingdom to help track the movements of enemy aircraft and control friendly aircraft.
A Sector clock or colour change clock was a round colour-coded clock used at military airfields and observation posts in the United Kingdom to help track the movements of enemy aircraft and control friendly aircraft.
Originally known as "colour change clocks", they were introduced during the First World War by the Royal Flying Corps in 1917 to monitor the movements of German aircraft. Later, during the Second World War they played a significant role in the Battle of Britain and continued to be used by the Royal Air Force and Royal Observer Corps (ROC) as simple clocks and keepsakes, until the end of the Cold War period. These clocks are now sought after by collectors of aeronautica.
There were two versions of the clock issued, either for RAF Sector use or for the ROC. The RAF Sector Clock has an old style "King's Crown" RAF Warrant Officer's insignia under the "24" at top centre. [1] The ROC clock has a plain face with no insignia.
Clocks were either electrical or mechanical. Electric clocks usually have the coloured segments pointing inwards, mechanical clocks have the segments pointing outwards. [2]
The United States Army Air Force (USAAF) also adopted the RAF sector clock with a coloured block pattern rather than triangles. [3]
The Sector Clock was a fundamental part of Ground-controlled interception (GCI) before modern computerized systems were put in place for airspace control. The clock face is marked with five-minute red, yellow and blue triangular segments. [4] It has an outer 12-hour ring and an inner 24-hour dial.
Aircraft position was recorded along with the colour of the triangle beneath the minute hand at the time of sighting. This was reported to sector headquarters, where counters of the relayed colour were used to represent each air raid on a large table with a map of the UK overlaid with a British Modified Grid. As the plots of the raiding aircraft moved, the counters were pushed across the map by magnetic "rakes". This system enabled "Fighter Controllers" to see very quickly where each formation was heading and allowed an estimate to be made of possible targets. The age of the information was readily apparent from the colour of the counter. Because of the simplicity of the system, decisions could be made quickly and easily.
RAF Fighter Command was one of the commands of the Royal Air Force. It was formed in 1936 to allow more specialised control of fighter aircraft. It served throughout the Second World War. It earned near-immortal fame during the Battle of Britain in 1940, when the Few held off the Luftwaffe attack on Britain. The Command continued until 17 November 1943, when it was disbanded and the RAF fighter force was split into two categories; defence and attack. The defensive force became Air Defence of Great Britain (ADGB) and the offensive force became the RAF Second Tactical Air Force. Air Defence of Great Britain was renamed back to Fighter Command in October 1944 and continued to provide defensive patrols around Great Britain. It was disbanded for the second time in 1968, when it was subsumed into the new Strike Command.
RAF Bentley Priory was a non-flying Royal Air Force station near Stanmore in the London Borough of Harrow. It was the headquarters of Fighter Command in the Battle of Britain and throughout the Second World War. The Royal Air Force station closed its operations on 30 May 2008, with all units relocating to new accommodation at RAF Northolt, a few miles away.
The Pathfinders were target-marking squadrons in RAF Bomber Command during World War II. They located and marked targets with flares, at which a main bomber force could aim, increasing the accuracy of their bombing. The Pathfinders were normally the first to receive new blind-bombing aids such as Gee, Oboe and the H2S radar.
RAF Carlisle was a Royal Air Force establishment, now closed after being used for a variety of roles over a period of fifty eight years and formerly located 2 mi (3.2 km) north of Carlisle city centre in Cumbria, England.
The Royal Observer Corps (ROC) was a civil defence organisation intended for the visual detection, identification, tracking and reporting of aircraft over Great Britain. It operated in the United Kingdom between 29 October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down. Composed mainly of civilian spare-time volunteers, ROC personnel wore a Royal Air Force (RAF) style uniform and latterly came under the administrative control of RAF Strike Command and the operational control of the Home Office. Civilian volunteers were trained and administered by a small cadre of professional full-time officers under the command of the Commandant Royal Observer Corps; latterly a serving RAF Air Commodore.
The United Kingdom Warning and Monitoring Organisation (UKWMO) was a British civilian organisation operating to provide UK military and civilian authorities with data on nuclear explosions and forecasts of fallout across the country in the event of nuclear war.
The officer ranks of the Royal Air Force, as they are today, were introduced in 1919. Prior to that Army ranks were used.
Aircraft recognition is a visual skill taught to military personnel and civilian auxiliaries since the introduction of military aircraft in World War I. It is important for air defense and military intelligence gathering.
Adlertag was the first day of Unternehmen Adlerangriff, an air operation by Nazi Germany's Luftwaffe intended to destroy the British Royal Air Force (RAF). The operation came during the Battle of Britain after Britain rejected all overtures for a negotiated peace with Germany. However, Adlertag and subsequent operations failed to destroy the RAF or gain local air superiority.
Royal Air Force Barton Hall or more simply RAF Barton Hall is a former Royal Air Force station situated between the villages of Barton and Broughton, near Preston, Lancashire, England.
Air Commodore Finlay Crerar, was a senior Royal Air Force officer during the Second World War who served as the fourth Commandant of the Royal Observer Corps (ROC). He led the ROC through the final two years of the war and the difficult period of the V-1 flying bomb raids on southern England.
Air Commodore Raymond John Offord, AFC was a senior Royal Air Force officer in the Cold War period, and the seventeenth Commandant Royal Observer Corps. Offord was Station Commander of RAF Lossiemouth from 1974 to 1975 and held the dual appointments of Air Officer Commanding Air Headquarters Cyprus and Deputy Commander, British Forces Near East / Cyprus from 1983 to 1985.
The Dowding system was the world's first wide-area ground-controlled interception network, controlling the airspace across the United Kingdom from northern Scotland to the southern coast of England. It used a widespread dedicated land-line telephone network to rapidly collect information from Chain Home (CH) radar stations and the Royal Observer Corps (ROC) in order to build a single image of the entire UK airspace and then direct defensive interceptor aircraft and anti-aircraft artillery against enemy targets. The system was built by the Royal Air Force just before the start of World War II, and proved decisive in the Battle of Britain.
Royal Air Force Harlaxton or more simply RAF Harlaxton is a former Royal Air Force station near the village of Harlaxton, 3 mi (4.8 km) south west of Grantham, Lincolnshire, England. The airfield was located in a triangle of flat fields midway between Harlaxton Manor and the nearby village of Stroxton.
The Battle of Britain Bunker is an underground operations room at RAF Uxbridge, formerly used by No. 11 Group Fighter Command during the Second World War. Fighter aircraft operations were controlled from there throughout the War but most notably during the Battle of Britain and on D-Day. Today it is run by Hillingdon Council as a heritage attraction with attached museum. The museum was opened in 1985, with an above ground visitor centre opened in March 2018.
Plotters were employed on an early form of air traffic monitoring that played a vital role in World War II, including during the Battle of Britain, The Blitz and the bombing of British cities that followed. They worked at individual RAF stations' Sector Control Rooms or in the central Group Control Rooms that directed the operations of RAF fighters. The majority of plotters were female, members of the Women's Auxiliary Air Force (WAAFs).
The Royal Observer Corps Orlit Post is an observation post used by the Royal Observer Corps during the Cold War to recognise enemy aircraft. Many Orlit Posts can be found near ROC Monitoring Posts.
Pip-squeak was a radio navigation system used by the British Royal Air Force during the early part of World War II. Pip-squeak used an aircraft's voice radio set to periodically send out a 1 kHz tone which was picked up by ground-based high-frequency direction finding receivers. Using three HFDF measurements, observers could determine the location of friendly aircraft using triangulation.
Lieutenant commander is a senior officer rank in the Royal Navy of the United Kingdom. It is immediately junior to commander and immediately senior to the naval rank of lieutenant.