Question: When did the company that made the AA.20 end by merging?

full_context: Document 1: Anti-aircraft warfare: Poland's AA defences were no match for the German attack and the situation was similar in other European countries. Significant AA warfare started with the Battle of Britain in the summer of 1940. 3.7-inch HAA were to provide the backbone of the groundbased AA defences, although initially significant numbers of 3-inch 20-cwt were also used. The Army's Anti-aircraft command, which was under command of the Air Defence UK organisation, grew to 12 AA divisions in 3 AA corps. 40-mm Bofors entered service in increasing numbers. In addition the RAF regiment was formed in 1941 with responsibility for airfield air defence, eventually with Bofors 40mm as their main armament. Fixed AA defences, using HAA and LAA, were established by the Army in key overseas places, notably Malta, Suez Canal and Singapore.
Document 2: Dassault Aviation: Dassault Aviation SA () is an international French aircraft manufacturer of military, regional, and business jets, and is a subsidiary of Dassault Group.
Document 3: SS.11: SS.11 is the designation of the Nord Aviation MCLOS wire-guided anti-tank missile. In American service, the missile was designated the "AGM-22". The missile entered service with the French Army in 1956. Production of the SS.11/SS.12 series ceased some time in the 1980s, by which time over 170,000 had been sold. The price of the SS.11 in the late 1960s was stated at approximately $1,900 U.S. dollars.
Document 4: Nord 1500 Griffon: The Nord 1500 Griffon was an experimental ramjet-powered fighter aircraft designed and built in the mid-1950s by French state-owned aircraft manufacturer Nord Aviation. It was part of a series of competing programs to fill a French Air Force specification for a Mach 2 fighter.
Document 5: Sabena: The Societé Anonyme Belge d'Exploitation de la Navigation Aérienne (French; "Belgian Corporation for Air Navigation Services"), better known internationally by the acronym Sabena or SABENA, was the national airline of Belgium from 1923 to 2001, with its base at Brussels National Airport. After its bankruptcy in 2001, the newly formed SN Brussels Airlines took over part of Sabena's assets in February 2002, which became Brussels Airlines after a merger with Virgin Express in March 2007. The airline's corporate headquarters were located in the Sabena House on the grounds of Brussels Airport in Zaventem.
Document 6: AA.20: The AA.20 was a French air-to-air missile, developed by Nord Aviation, and was one of the first of such missiles adopted into service in Western Europe. Production began at Chatillon, France in 1956. Approximately 6,000 missiles of the type were produced, remaining in service until 1960.
Document 7: Nord Aviation: The company was based in the centre of France, on the site of Bourges airport, in the département of Cher. In 1970, Nord Aviation merged with Sud Aviation to create "Société nationale d'industrie aérospatiale" (SNIAS), later renamed Aérospatiale and ultimately merged into European aerospace corporation Airbus in 2000.
Document 8: Tupolev Tu-22: The Tupolev Tu-22 (NATO reporting name: Blinder) was the first supersonic bomber to enter production in the Soviet Union. Manufactured by Tupolev, the Tu-22 entered service with the Soviet military in the 1960s. The last examples were retired during the 1990s. Produced in comparatively small numbers, the aircraft was a disappointment, lacking the intercontinental range that had been expected. Later in their service life, Tu-22s were used as launch platforms for the Soviet Kh-22 standoff missile, and as reconnaissance aircraft. Tu-22s were sold to other nations, including Libya and Iraq. The Tu-22 was one of the few Soviet bombers to see combat; Libyan Tu-22s were used against Tanzania and Chad, and Iraqi Tu-22s were used during the Iran–Iraq War.
Document 9: Anti-aircraft warfare: Initially sensors were optical and acoustic devices developed during the First World War and continued into the 1930s, but were quickly superseded by radar, which in turn was supplemented by optronics in the 1980s. Command and control remained primitive until the late 1930s, when Britain created an integrated system for ADGB that linked the ground-based air defence of the army's AA Command, although field-deployed air defence relied on less sophisticated arrangements. NATO later called these arrangements an "air defence ground environment", defined as "the network of ground radar sites and command and control centres within a specific theatre of operations which are used for the tactical control of air defence operations".
Document 10: Scottish Aviation: In November 1958, redundancies affecting almost 800 of their 2,500 staff were announced. Scottish Aviation merged with the British Aircraft Corporation, Hawker Siddeley Aviation, and Hawker Siddeley Dynamics to form British Aerospace in 1977. Much of the former Scottish Aviation assets now belong to Spirit AeroSystems.
Document 11: British Aerospace: The GEC merger to create a UK company compared to what would have been an Anglo-German firm, made the possibility of further penetration of the United States (US) defence market more likely. The company, initially called "New British Aerospace", was officially formed on 30 November 1999 and known as BAE Systems.
Document 12: MILAN: MILAN (; , "milan" is French for kite) is a European anti-tank guided missile. Design of the MILAN started in 1962, it was ready for trials in 1971, and was accepted for service in 1972. It is a wire guided SACLOS (semi-automatic command to line-of-sight) missile, which means the sight of the launch unit has to be aimed at the target to guide the missile. The MILAN can be equipped with a MIRA or MILIS thermal sight to give it night-firing ability.
Document 13: ANF Industrie: Ateliers de Construction du Nord de la France was a French locomotive manufacturer, based at Crespin in the Arrondissement of Valenciennes, northern France. Later known as ANF Industrie or ANF the company was acquired by Bombardier Transportation in 1989 and is now part of Bombardier Transport France S.A.S.
Document 14: Anti-aircraft warfare: The introduction of the guided missile resulted in a significant shift in anti-aircraft strategy. Although Germany had been desperate to introduce anti-aircraft missile systems, none became operational during World War II. Following several years of post-war development, however, these systems began to mature into viable weapons systems. The US started an upgrade of their defences using the Nike Ajax missile, and soon the larger anti-aircraft guns disappeared. The same thing occurred in the USSR after the introduction of their SA-2 Guideline systems.
Document 15: Paris: Orly Airport, located in the southern suburbs of Paris, replaced Le Bourget as the principal airport of Paris from the 1950s to the 1980s. Charles de Gaulle Airport, located on the edge of the northern suburbs of Paris, opened to commercial traffic in 1974 and became the busiest Parisian airport in 1993. Today it is the 4th busiest airport in the world by international traffic, and is the hub for the nation's flag carrier Air France.  Beauvais-Tillé Airport, located 69 km (43 mi) north of Paris' city centre, is used by charter airlines and low-cost carriers such as Ryanair.
ground_truth: 1970
sub_queries: Which corporation created AA.20? Answer: Nord Aviation
Which year did Nord Aviation end? Answer: 1970