Stimulation vs Emulation – The Fidelity Issue

Due to the advantages mentioned in our previous posts, emulation is favored over stimulation in nearly all modern simulator applications.  However, there is one additional concern associated with the use of emulation versus stimulation. Particularly for the Apache crew training, where most trainers use stimulation.

This issue is the concern that any deficiencies in the fidelity of the simulation may introduce negative training. The assumption then becomes that by utilizing aircraft operational software, despite the significant drawbacks as outlined above, the fidelity of the trainer is the highest that can be realized.  

Reverse Engineering Methodology

The potential for improper behavior training using emulation is addressed by the utilization of a proven reverse engineering methodology. This is to ensure the most accurate and highest fidelity simulation. Also, to realize the significant advantages of implementing the simulation approach while avoiding the many drawbacks to the stimulated approach.

This engineering methodology uses significant processing power in commercial computers. This is needed to provide an emulation of actual system performance in every practical operating mode.

This emulation is based on system documentation, data, photographs, and analysis of the actual operation of the aircraft. It is also based on direct feedback from pilots and Subject Matter Experts. This is to ensure that the emulation matches the OV at the user interface.  Use cases have been developed which accurately and thoroughly describe the operation of the aircraft software. As well as the capabilities based on all these sources of information.

The implementation of these use cases categorizes the operation of the aircraft and its various subsystems from the crewmembers’ perspective. Both what the crewmember observes and how the aircraft responds. These are captured in each use case to achieve an accurate simulation.   

The methodology has been refined over several years and has resulted in a highly accurate emulation of most aircraft. This includes the Apache attack helicopter.  The British Army and the United Arab Emirates Land Forces both employ Apache Longbow simulators that utilize emulations of their aircraft configuration with great success.


While the stimulation approach claims to minimize improper behavior and negative training there are several significant disadvantages to utilizing operational aircraft equipment.  These disadvantages include aircraft concurrency which itself introduces negative training.

In contrast, the several advantages to the emulation, or “simulated” approach now present a favorable solution for the trainer application.  As past successful programs have proven, this approach can be used effectively for the most demanding training applications which include the demanding training tasks of Apache attack helicopters.

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Initially, Applied Visual Technology Inc., AVT has been developing modeling and simulation expertise through engineering services since 1998. This is due to our founder who has accumulated over 30 years of military MS&T expertise in aviation applications. Nonetheless, everyone at AVT specializes in making old training systems new again and making new ones for less. Consequently, for 20 years AVT has served our Air Force, Army, Navy, and Marine customers by providing the highest quality of service and solutions. Following its inception, AVT’s highly specialized staff of engineers has included some of the top leaders in the simulation industry. With over 20 years of simulation experience, our dedicated team provides specialized solutions for customers with complex problems.