The fidelity of a rotorcraft flight simulator is influenced by many factors, such as the vehicle dynamic model and the motion cueing algorithm (MCA). To quantify the fidelity of a simulator objectively requires detailed knowledge of human pilot perception and control behaviour that is not yet available. As a consequence, subjective assessments made by qualified pilots remain the most important way to assess flight simulation fidelity. The use of standardized rating scales during such assessments can increase the level of objectivity above that provided by less structured evaluations. The current paper describes the result of an experiment performed on the Desdemona simulator to evaluate two rating scales, namely the Simulator Fidelity Rating (SFR) scale and the Motion Fidelity Rating (MFR) scale, as suitable indicators of flight simulation fidelity. In this experiment, two characteristics of the simulated environment were varied, namely rotorcraft dynamics and MCA configuration, and the type of rating scale used was treated as an additional independent variable. The primary results of the experiments suggest that pilots are able to recognize a strong decline in flight simulation fidelity when both rotorcraft dynamics and motion are degraded simultaneously. However, when either one of these characteristics are varied independently of the other, the results are inconclusive. The paper presents a more detailed review of the various results gathered during the experiment and formulates recommendations for future experiments in rotorcraft flight simulation fidelity assessment that involve the use of pilot ratings.@en