is achieved by: maintaining general airspace control preventing unauthorised airspace intrusion through round the clock radar coverage (to be expanded by activation of ground based air defence (GBAD) units) a 24/7 air policing as an active airspace protection. Its secondary missions are executing airlift, reconnaissance operations, and gathering and interpreting intelligence for the Swiss political and military leadership. Status Through the years, the Swiss Air Force traditionally had been a militia-based service, including its pilots. Its inventory existed of approximately 450 aircraft whose operational service life overlapped several eras. Beginning with its separation from the army in 1966 the Air Force has been reduced in size (currently about 230 fixed and rotary-wing aircraft) moving towards a small professional cadre with fewer reserves and conscripted supporting personnel. Currently the Swiss air force has a peacetime strength of 1,600 career military and about 20,000 reservists on call. Its air defence consists of 30 McDonnell Douglas F/A-18 Hornets and 53 Northrop F-5 Tiger IIs (110 purchased in 1978–85). The F/A-18 pilots are career military; the F-5 pilots however are reservists (mostly air- or freight-liner pilots with F-5 rating). During reserve duty periods they are assigned to military duties refreshing their operational live flying training and rating. In 2008, the Swiss F-18 component reached its 50,000 flight hour milestone. Due to the RUAG Upgrade 21 (UG21) programme between 2004 and 2009 and the Mid-Life Update (MLU) its operational lifecycle will be guaranteed until 2022. From 2011 the air force intended to start the Partial F-5 Tiger Replacement programme for 22 new aircraft with the JAS 39 Gripen, Eurofighter Typhoon and Dassault Rafale as replacement candidates. In November 2011 the Swiss government announced its decision to buy 22 Gripen New Generation fighters. The contract for the 22 aircraft was signed at 3.1 billion Swiss francs. On 25 August 2012, the order was confirmed by both the Swedish and Swiss authorities. The first new aircraft would be delivered in 2018 and the intention was to lease 11 current generation (eight JAS 39Cs/3 JAS 39Ds) Gripen fighters from 2016 to 2020 in order to train Swiss fighter pilots while avoiding expensive upkeep of the F-5s. However, in a national referendum in May 2014 a majority of Swiss rejected the purchase of the Gripen. This included continued operation of the Patrouille Suisse on F-5E. To reduce the risk of a negative referendum outcome the Swiss defence ministry revised