Control (OPCON) is delegated to the Joint Helicopter Command, under Army Command, who will task assets in accordance with Permanent Joint Headquarters or Front Line Command requirements. Organisation The Commando Helicopter Force has three Naval Air Squadrons with separate roles: 845 Naval Air Squadron – Medium-lift front line operations – Merlin HC4/4A 846 Naval Air Squadron – Medium-lift Operational Conversion Unit and Maritime Counter Terrorism Air Group (MAG) – Merlin HC4 847 Naval Air Squadron – Light-lift and battlefield reconnaissance – Wildcat AH1 A Combat Service Support Squadron and Commando Mobile Air Operations Team also form part of CHF. 845 and 846 NAS received Merlin HC3s/HC3As to replace the retiring Sea Kings in 2014 and 2015. 846 NAS took their Merlin HC3s on 30 September 2014; 845 NAS followed on 9 July 2015. These are being upgraded to the Merlin HC4/4A as part of the Merlin Life Sustainment Programme (MLSP). The Merlin HC4 has a grey colour scheme, not the dark green colour of the "Junglie" Sea Kings. Concurrently, 847 NAS has come to the end of the process of upgrading to the AgustaWestland AW159 Wildcat. 845 Naval Air Squadron 845 NAS operated the Westland Sea King HC Mk4 helicopter; a variant that has been specially modified for medium-lift transport and flying in all sorts of weather conditions and terrains. 845 had at least two of it Sea Kings deployed to the Bosnian theatre since 1992. Besides Bosnia, they have operated in Albania, Egypt, Honduras, Nigeria, Sierra Leone, Iraq and Afghanistan. 845 NAS was temporarily stationed at RAF Benson in Oxfordshire as part of the Merlin transition until it relocated back to RNAS Yeovilton on 20 June 2016. 846 Naval Air Squadron 846 NAS operates with 845 NAS, but has not seen action in Bosnia, being more focused on the Northern flank of the NATO theatre. Until recently, 846 maintained a base in Northern Ireland that allowed it to become very proficient in cold weather and winter operations. However, squadron operations are not limited to northern flying conditions and it has operated in South East Asia, Australia, the United States, and Germany. Two of the squadron's aircraft were sent to Turkey following the major earthquake it suffered in November 1999. 846 NAS was temporarily stationed at RAF Benson in Oxfordshire as part of the Merlin transition until it relocated back to RNAS Yeovilton on 26 March 2015. In March 2016,