Operational Conversion Unit (OCU). Typhoon T1 The Typhoon T1 is a Tranche 1, batch 1 two-seat trainer. The first Typhoon T1 is one of the Instrumented Production Aircraft (IPA1) and remains part of the BAE fleet. The aircraft's maiden flight was on April 15, 2002. The official in service date for the first RAF Typhoon T1, serial ZJ803, was June 30, 2003. Formal delivery occurred on December 18 at which point 17 Sqn began a full flying programme. The first squadrons, No. 17 OEU and No. 29 OCU Sqns, moved to RAF Coningsby in 2005 to begin establishing an initial operational capability (IOC). In 2001, it was announced that the Royal Air Force (RAF) would not use the aircraft's internal 27 mm Mauser cannon. This was due to a desire to save money by removing gun support costs, ammunition stocks, training costs, etc. The gun was also deemed unnecessary since the missile armament was believed to be adequate in the Typhoon's fighter role. However, because removal of the cannon would affect the aircraft's flight characteristics, requiring modification of the aircraft's flight software the RAF decided all its Typhoons would be fitted with the cannon but that it would not be used or supported. The service argued that this would save money by reducing the requirement for ground equipment, removing training costs and avoiding the fatigue effects of firing the cannon. The RAF maintained the option to activate the cannons at very short notice were operational requirements to change. However, in a third change of policy, The Daily Telegraph reported on 3October 2006 that the RAF will fully utilise the cannon. Typhoon T1A Typhoon T1As are Tranche 1, batch 2 two-seat trainers. There would not normally be a different designation for a different aircraft batch; however, the Batch2 aircraft has a fuel system modification to fix a fuel gauge problem identified in the development aircraft fleet. Typhoon F2 The F2 is the single-seat fighter variant. The first F2 is IPA5 and also remains with BAE, its first flight was June 6, 2002. The first operational squadron, No. 3, formed at RAF Cottesmore on March 31, 2006 and moved to its new base RAF Coningsby the following day. No. 11 squadron, the second operational squadron received its first aircraft (ZJ931) on October 9, 2006. As of June 2018, the RAF had bought 53 Tranche 1 Typhoons. The UK agreed to approve production