Flight Models and FAA Approval of Training Devices

Many pilots and flight instructors obsess about the fidelity of the “flight models” (the more formal term is “flight dynamics”) of PC-based simulations and flight training devices (FTDs). They equate detailed, accurate flight dynamics for specific aircraft with FAA approval, but the FAA actually imposes few specific requirements on the flight modeling for ATDs and BATDs [see AC 61-136 – FAA Approval of Basic Aviation Training Devices (BATD) and Advanced Aviation Training Devices (AATD)].

ATDs and BATDs often use Microsoft Flight Simulator or X-Plane as the core of the software component of the training device. [The requirements for more sophisticated FTDs (which are approved at several levels) are spelled out in detail in Appendix B to Part 60—Qualification Performance Standards for Airplane Flight Training Devices of the FARs.]

For example, Appendix 2 of AC 61-136 includes detailed requirements about the controls and displays required for FAA approval, but about flight dynamics it (in paragraph e) says only:

(1) Flight dynamics of the ATD should be comparable to the way the represented training aircraft performs and handles. However, there is no requirement for an ATD to have control loading to exactly replicate any particular aircraft. . .

(2) Aircraft performance parameters (such as maximum speed, cruise speed, stall speed, maximum climb rate, hovering/sideward/forward/rearward flight) should be comparable to the aircraft or family of aircraft being represented.

(3) Aircraft vertical lift component must change as a function of bank, comparable to the way the aircraft or family of aircraft being represented performs and handles.

(4) Changes in flap setting, slat setting, gear position, collective control or cyclic control must be accompanied by changes in flight dynamics, comparable to the way the aircraft or family of aircraft represented performs and handles.

(5) The presence and intensity of wind and turbulence must be reflected in the handling and performance qualities of the simulated aircraft and should be comparable to the way the aircraft or family of aircraft represented performs and handles.

Note the language about “the aircraft or family of aircraft.” As long as the simulated airplane reacts to control inputs as a typical airplane of that category and class does, the FAA is satisfied. There’s no requirement that a BATD or ATD model a specific aircraft or even use a detailed aerodynamic model.

In fact, with regard to FTDs and all ATDs and BATDs, the FAA is most concerned with the controls, instruments, and switches in the cockpit and the visual displays than it is with the handling qualities of the simulation–provided the virtual aircraft, in general, behaves, for example, like a generic single-engine or multiengine airplane.

Now, this isn’t to suggest that flight dynamics aren’t important, or that flight simulations shouldn’t strive for high fidelity. But implicit in the FAA approval standards is the idea that FTDs, ATDs, and BATDs can play many roles in aviation training without having to replicate a specific make, model, or type of aircraft.

That’s a central theme of my two books about using PC-based simulations in flight training, Scenario-Based Training with X-Plane and Microsoft Flight Simulator: Using PC-Based Flight Simulations based on FAA and Industry Training Standards (published January 2012) and Microsoft Flight Simulator as a Training Aid (published in January 2007).

If you’re considering using a simulation to complement your training, focus on what PC-based simulations, including BATD and ATD, do best–help you learn and master important skills and procedures–how to think like a pilot. Don’t dismiss a simulation just because it doesn’t exactly reproduce the aircraft you fly.

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