Testing novel concepts in the allocation and use of aircraft is commonly done in air traffic simulators. Current day simulators rely on proprietary models and often propose questionable solutions. This paper uses BlueSky as simulator, in cooperation with performance models OpenAP and BADA. BlueSky aims to provide the user with full freedom to simulate any scenario. Improving BlueSky and adding functionality further aids in this goal. By expanding logic of the simulator, the user should attain more functionality without compromising the user-friendliness of BlueSky. This paper treats the implementation of thrust setting and flight path angle in BlueSky. This enables continuous descent operations to become part of the possibilities within BlueSky. The challenge was to prepare a set of ADS-B data using Fuzzy logic to validate the new model. Its robustness was then be demonstrated using a large number of flights.