The performance and emission levels of a 160 N (35 lbs) thrust gas micro-turbine, running on blends of kerosene and waste cooking oil (methyl ester), were investigated over the take-off, cruise and idle phases of a typical flight profile. We considered three blends with biofuel volume fractions of 15%V (B15), 30%V (B30) and 90%V (B90). Relevant quantities such the thrust, the specific fuel consumption (SFC), the exhaust gas temperature (EGT), the unburned hydrocarbons (HC), and the production of O2, CO, CO2, NOx, were analyzed. Their time-weighted behavior was then plotted as a function of the blend type. It was found that an optimal fuel blend may be approximately defined by the equilibrium between two main contending factors: a) the production of thrust, and b) the amount of gas emissions. Also, it was observed that low blends (e.g. B15) produced thrust and SFC levels similar to those of kerosene, while high blends (e.g. B90) significantly reduced the gas emission levels at the expense of thrust production.