*It is important to note that many simulators may contain specific features or abilities not explicitly stated in their level of certification. Every simulator, especially custom built designs, are able to be customized in order to fit any facility needs even if a desired level of certification does not necessarily require it. Any ambiguities with respect to the capabilities of the simulator are finalized in the sales contract and technical specifications document prior to the simulator deal closing.
The FFS, or Full Flight Simulators, is the most advanced category for flight simulation. This category is broken up into four categories, Level A, B, C, and D. Typically, these simulators cost millions of dollars and are targeted at airlines and airline training facilities. Level A is a motion system with at least three degrees of freedom. This category is reserved for airplanes only. Level B is a three-axis motion system and a higher-fidelity aerodynamic model than Level A. The lowest level of helicopter flight simulator is Level B. Level C is a motion platform with six degrees of freedom, also a lower transport delay (latency) over levels A or B. The visual system must have an outside-world horizontal field of view at least 75 degrees for each pilot. Level D is the king of simulators. This is the highest level of FFS qualification available. All the previous requirements for Level C are required, and the motion platform must have all six degrees of freedom, and the visual system must have an outside-world horizontal field of view at least 150 degrees, with a collimated (distant focus) display. Realistic sounds in the cockpit are required, as well as a number of special motion and visual effects. This simulator category is used for professional airlines to train in jet aircraft generally.