page_title: Night fighter
section_title: World War II
hierarchical_section_title: Night fighter / History / World War II
caption_attribution_description: Deutsch: Das Anzeigerät für Funknavigation AFN2 enthält zwei Drehspuhlmeßwerke, von denen das einen auf eninen waagerecht, das andere auf einen senkrecht angeordneten Zeiger wirkt. Der senkrechte zeiger wird für Kursanzeige, der waagerechte für die Anzeige der Empfänger-Ausgangsspannung benutzt. Die in der Mitte der Skala sichtbare, in den Anschlußstecker des AFN2 eingebaute Anzeigeglimmlampe, bleibt unbenutzt für EZ6.
context_page_description: A night fighter is a fighter aircraft adapted for use at night or in other times of bad visibility. Night fighters began to be used in World War I and included types that were specifically modified to operate at night.
  During World War II, night fighters were either purpose-built night fighter designs, or more commonly, heavy fighters or light bombers adapted for the mission, often employing radar or other systems for providing some sort of detection capability in low visibility. Many WW II night fighters also included instrument landing systems for landing at night, as turning on the runway lights made runways into an easy target for opposing intruders. Some experiments tested the use of day fighters on night missions, but these tended to work only under very favourable circumstances and were not widely successful.
  Avionics systems were greatly miniaturised over time, allowing the addition of radar altimeter, terrain-following radar, improved instrument landing system, microwave landing system, Doppler weather radar, LORAN receivers, GEE, TACAN, inertial navigation system, GPS, and GNSS in aircraft.
context_section_description: The war opened on 1 September 1939, and by this time, the RAF were well advanced with plans to build a radar – then called 'RDF' in Britain – equipped night-fighter fleet. The Airborne Interception Mk. II radar (AI Mk. II) was being fit experimentally to a small number of Bristol Blenheim aircraft and the first prototype system went into service in November 1939, long before the opening of major British operations. These early systems had significant practical problems, and while work was underway to correct these flaw, by the time the Blitz opened in August 1940 the night fighter fleet was still in its infancy.
  Through this period, the RAF experimented with many other aircraft and interception methods in an effort to get a working night fighter force. One attempt to make up for the small number of working radars was to fit an AI to a Douglas Havoc bomber which also carried a searchlight in its nose. These Turbinlite aircraft were intended to find the targets and illuminate them with the searchlight, allowing Hurricanes adapted for night flying to shoot them down visually. This proved almost impossible to arrange in practice, and the Cat Eye fighters had little luck during the closing months of 1940.
  By early 1941 the first examples of a production-quality radar, AI Mk. IV, were beginning to arrive. This coincided with the arrival of the Beaufighter, which offered significantly higher performance than the pre-war Blenheims. Over the next few months, more and more Beaufighters arrived and the success of the night fighters roughly doubled every month until May, when the Luftwaffe ended their bombing efforts. Although night bombing never ended, its intensity was greatly decreased, giving the RAF time to introduce the AI Mk. VIII radar working in the microwave band, and the de Havilland Mosquito to mount it. This combination remained the premier night fighter until the end of the war.
  As the German effort wound down, the RAF's own bombing campaign was growing. The Mosquitos had little to do over the UK, so a number of squadrons were formed within No. 100 Group RAF and fit with special systems  such as Perfectos and Serrate, for homing-in on German night fighters. The British also experimented with mounting pilot-operated AI Mark 6 radar sets in single-seat fighters, and the Hurricane II C(NF), a dozen of which were produced in 1942, became the first radar-equipped, single-seat night fighter in the world. It served with 245 and 247 Squadrons briefly and unsuccessfully before being sent to India to 176 Squadron, with which it served until the end of 1943. A similarly radar-equipped Hawker Typhoon was also produced, but no production followed.
  German airborne interception radar efforts at this point were about two years behind the British. Unlike in Britain, where the major targets lay only a few minutes' flight time from the coast, Germany was protected by large tracts of neutral territory that gave them long times to deal with intruding bombers. Instead of airborne radar, they relied on ground-based systems; the targets would first be picked up by radar assigned to a "cell", the radar would then direct a searchlight to "paint" the target, allowing the fighters to attack them without on-board aids. The searchlights were later supplanted with short-range radars that tracked both the fighters and bombers, allowing ground operators to direct the fighters to their targets. By July 1940, this system was well developed as the Kammhuber Line, and proved able to deal with the small raids by isolated bombers the RAF was carrying out at the time.
  At the urging of R.V. Jones, the RAF changed their raid tactics to gather all of their bombers into a single "stream". This meant that the ground-based portion of the system was overwhelmed; with only one or two searchlights or radars available per "cell", the system was able to handle perhaps six interceptions per hour. By flying all of the bombers over a cell in a short period, the vast majority of the bombers flew right over them without ever having been plotted, let alone attacked. German s
caption: Luftwaffe instrument landing system indicator, built 1943
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