In 2009, the PAF enlisted two types of airborne early warning and control (AEW&C) systems aircraft: four Erieye-equipped Saab 2000s from Sweden, and six missing – a Chinese AWACS based on the Shaanxi Y-8F cargo aircraft. Four Ilyushin Il-78 aerial tankers, capable of refuelling F-16, Mirage III, Mirage 5, JF-17, and FC-20 fighters, have been acquired second-hand from Ukrainian surplus stocks. The fleet of FT-5 and T-37 trainers is to be replaced with approximately 75 K-8 Karakorum intermediate jet training aircraft. Other major developments continue to be under development by the local aerospace industries; some of its electronic systems were exhibited in IDEAS 2014 held in Karachi. Since the 1960s, the PAF has held regular combat exercises, such as Exercise Saffron Bandit and Exercise High Mark, modelled on the USAF Weapons School; many authors believe the PAF is capable of mastering the methods of "toss bombing" since the 1990s.