backbone of the training fleet, however, is built around 20 Pilatus PC-9M advanced trainers which also constitute the most numerous type of aircraft in Croatian service. These were ordered in 1997 (3 were former RAAF PC-9A examples converted to PC-9M standard immediately upon delivery) and entered full service a year later. The deal was worth around $100 million. They are also operated by the national aerobatic team called Krila Oluje / Wings of Storm. The fleet size and facilities at Zemunik airbase allow the Croatian Air Force to offer advanced pilot training to other countries but the lack of HUDs, HOTAS and weapon stations on Croatia's PC-9Ms, however, limits the usefulness of Croatia's advanced training programme. Such upgrades might be financially plausible once surplus PC-9Ms get sold. Nonetheless, on March 5, 2014, representatives of the Croatian Air Force signed an agreement with their partners from the Royal Air Force of Oman for the future training and education of 16 Omani pilots on the Croatian fleet of Pilatus PC-9Ms. The training itself started on March 10, is planned to be concluded by December 26, 2014 and will see each pilot log 150 flight hours during the ten-month period. As a cost-saving measure, the Croatian government has announced in its long-term defence plan that it plans to downsize the PC-9M fleet to a "suitable level" for the current air force fleet, substantially reduced since the mid-1990s. Consequently, six oldest units are offered for sale while the 14 remaining aircraft are due to remain active and possibly undergo an upgrade. The Croatian Air Force operated two Antonov An-32B tactical transports (built in 1991 and 1993) until 2013. Both aircraft underwent a two-stage modernisation in 2004 and 2007. They were fitted with NATO-standard navigational and communication equipment, additional systems for loading/unloading and flare dispensers. They had performed humanitarian and paratrooper missions as well as supporting Croatia's international military commitments such as for ISAF and KFOR. Due to budget limitations both aircraft have been offered for sale. In the draft of the strategic defence review, the Croatian government announced that no new tactical transport aircraft would be purchased before 2020 leaving Croatia reliant on its NATO partners for fixed-wing transport. The helicopter fleet is equipped mainly with Russian-built Mi-17s and its derivates. The fleet includes three Mi-8 and 11 Mi-8MTV-1 (also known as Mi-17-1V) cargo helicopters, which underwent overhauls between 2003 and 2005. A batch