comprise two VHF/UHF radios; the VHF radio has the capacity for data linking for communication with ground control centers, airborne early warning and control aircraft and combat aircraft with compatible data links for network-centric warfare, and improved situation awareness. The aircraft uses RLGs along with GPS for navigation. The aircraft is equipped with an IFF Transponder which allows it to differentiate between friendly aircraft and enemy aircraft. The ACMI aids in aerial combat for maneuvering. Engine The first two blocks of JF-17 is powered by a single Russian RD-93 turbofan engine, which is a variant of the Klimov RD-33 engine used on the MiG-29 fighter. The engine gives more thrust and significantly lower specific fuel consumption than turbojet engines fitted to older combat aircraft being replaced by the JF-17. The advantages of using a single engine are a reduction in maintenance time and cost when compared to twin-engined fighters. A thrust-to-weight ratio of 0.99 can be achieved with full internal fuel tanks and no external payload. The engine's air supply is provided by two bifurcated air inlets (see airframe section). The RD-93 is known to produce smoke trails. The Guizhou Aero Engine Group has been developing a new turbofan engine, the WS-13 Taishan, since 2000 to replace the RD-93. It is based on the RD-33 and incorporates new technologies to boost performance and reliability. A thrust output of , a lifespan of 2,200 hours, and a thrust-to-weight ratio of 8.7 are expected. An improved version of the WS-13, developing a thrust of around (22,450 lb), is also reportedly under development. During the 2015 Paris Air Show, it was announced that flight testing of a JF-17 equipped with the WS-13 engine had begun. In 2015, a representative of PAC said that Pakistan would continue to use the RD-93 engine on their fighters. Local media reports in January 2016 said that Russia was planning to sell engines for JF-17 directly to Pakistan. According to a PAC representative, Pakistan is looking to collaborate with Russia in developing and repairing engines. Fuel system The fuel system comprises internal fuel tanks located in the wings and fuselage with a capacity of ; they are refuelled through a single point pressure refuelling system (see turbine fuel systems). Internal fuel storage can be supplemented by external fuel tanks. One drop tank can be mounted on the aircraft's centerline hard point under the fuselage and two 800-litre or