On 1 October 1966 the IAF established its first Operational Training Unit (OTU) at Jamnagar with 24 Hunter aircraft (four trainers and 20 fighters) drawn from the six Hunter Mk.56 equipped squadrons, as was also the ground equipment and most of its human resources. The OTU was given a dual role: ‘training’ for which it came under HQ WAC at Palam and ‘operations’ for which it came under HQ WI (Western India) in Poona. Operational Conversion Units (OCU), The Young Ones’. On 1 Oct 66, BA313 , 02 officers (Wg Cdr Parker and Flt Lt TR Patel) and 06 airmen setup the establishment. Its purpose was to ensure the smooth transition of young pilots from training into the front line squadrons. The first intake showed up on 11 Oct 1966 and included pilots from 95 PC and were sent to squadrons on 1 May 1967. During the 1971 Indo-Pak War it operated a four aircraft detachment from Jaisalmer and was temporarily known as 122 Squadron. On the 5th December 1971 a regiment of Pakistan Army T59 Tanks crossed the border near Tanot, with the aim of capturing Jaisalmer by sun down. Following a request to help from the Indian Army, the detachment destroyed or damaged 29 tanks in 48 hours. This action stopping the enemy advance in its tracks and earning the Units the battle honour of ‘Longewala’. During the 1971 War the OCU flew 256 sorties and apart from Longewala also carried out interdiction strikes against enemy railheads and counter air strikes against airfields and radar stations. Flying training resumed in February 1972 and in April 1975 the Units moved to Kalaikunda and was renamed the OCU. It was also for most of the 80s called HOFTU (Hunter Operational Flying Training Unit). On 31st March 1991 the OCU was numberplated and all its assets were transferred to 20 Squadron. On 1st January 1998 it was resurrected at Chabua to implement the MOFT Syllabus on the MiG-21 FL/U, taking over aircraft from 20 Sqn. It moved out from Chabua to Kalaikunda in 2009. In December 2013 the OCU phased out MiG-21 FL's which it had been flying since 1998.