The Icing Encounter Flight Simulator is one part of the Smart Icing System project at the University of Illinois at Urbana-Champaign. The goal of the Smart Icing System project is to develop technology necessary to improve the safety of aircraft flying in icing conditions. The icing simulator is used as a platform to integrate different components of the Smart Icing System and to test the effectiveness of the components. To create an Icing Encounter Flight Simulator, functionality and Smart Icing System components were added to the FlightGear flight simulator, an open source flight simulator available on the internet. A reconfigurable aircraft model, an autopilot, and an icing model were some of the functionality added to FlightGear. Smart Icing System components integrated into the simulator include the neural-network-based icing characterization, envelope protection system, ice protection system, and an Ice Management System enhanced glass cockpit. To ensure a real-time simulation, computationally extensive processes have been distributed over several computers linked together by a local network. A tailplane stall scenario and a roll upset scenario have been designed to demonstrate the effectiveness of the Smart Icing System components on a nonlinear aerodynamics model of a DHC-6 Twin Otter aircraft in clean and iced conditions.