SIMULATIONS Changing the Paradigm

Although the month of May 2000 was ordinary by most standards, it was extraordinary for the Air Defense Artillery Test Directorate, U.S. Army Operational Test Command. During the Patriot Advanced Capabilities Configuration-3(PAC-3) Limited User Test (LUT) conducted at Fort Bliss, Texas, simulation took its place as the main vehicle in an air defense operational test. Over the course of approximately four weeks of test time, crews of the test player unit, the 2nd Battalion, 1st Air Defense Artillery, 35th ADA Brigade, Fort Bliss, engaged multiple simulated Air-Breathing Threat (ABT) and Tactical Ballistic Missile (TBM) targets in 120 realistic threat air battle scenarios. During this phase of operational testing, not a single live aircraft or missile took to flight. At the same time, however, all testing was effective in terms of data adequacy and cost reduction. In fact, with simulation at the helm via the PAC-3 Mobile Flight Mission Simulator (MFMS) test tool, the cumulative cost of creating and engaging the enemy totaled approximately $600 thousand--less than the cost of firing a single Patriot missile.

The MFMS Tool
At first glance, the MFMS appears to be an ordinary military vehicle (see figure 1), but its capabilities extend far beyond that. The PAC-3 Configuration 3 MFMS is a hardware-in-the-loop (HWIL) test system for Patriot that is able to simulate a variety of enemy air vehicles through pre-programmed threat air battle scenarios. These threats include various types of TBMs, ABTs, and Air-to-Surface Missiles (ASMs). The threat targets have multiple arrival times and designated ground impact points (GIPs) that require the Patriot system to engage multiple targets simultaneously. The scenarios are not a random generation of targets, but they are rather a true-to-life representation of known Patriot threats across the globe. This feature significantly increases the realism factor of the air battle in each scenario developed.

While the mobility aspect of the simulator is relatively new, the origins of the system are not. The Raytheon Corporation Patriot Program Office originally conceived the Flight Mission Simulator (FMS) in 1974 with the purpose of creating a tool for engineering and development. Eventually, Raytheon intended to use the FMS tool for system developmental testing. The idea was to exercise and test the Patriot system without altering its tactical configuration. The fire unit equipment would be set up in normal configuration and simply connected via the Patriot radar to the FMS for artificial target insertion. Initial success came later that year; this first version of the FMS was able to inject Radio Frequency (RF) signals into the system radar for one simulated target. Within four years, the FMS had the capability to stimulate the radar with up to 10 targets. Numerous software and hardware improvements have followed. The test tool is now capable of stimulating the Patriot system with the maximum number of targets allowed by the tactical system software. Raytheon added mobility in 1995 by creating a truck-mounted FMS; this was the evolution of the MFMS. Although engineering, development, and developmental testing were the original intentions of the FMS, this mobility allowed for tactical use and a bridge to the realm of operational testing. After an extensive verification, validation, and accreditation process according to Army Regulation 5-11 and Operational Test Command Handbook 73-21, the MFMS was certified as a viable test tool.

The test bed configuration is depicted photographically in figure 2 and diagrammatically in figure 3. The Engagement Control Station (ECS) is hardwired to the Radar Set (RS) and the RS is hardwired to the MFMS. Additionally, the Communications Relay Group (CRG) van links by wire to the ECS.

The Information Coordination Central (ICC) communicates with the ECS via Patriot Digital Information Link (PADIL), and it also communicates with the Communications, Control, and Command Engineering Environment System (C3EES) via Tactical Digital Information Link (TADIL) J. This is done to emulate a Joint Defense Network and ensure the system is capable of communicating in a joint environment via the TADIL-J messaging system. The Battery Maintenance Center wires into the ECS to collect system maintenance and status data via its Remote Maintenance Monitor (RMM) on the Patriot Automated Logistics System (PALS) computer. Simulating the Patriot Launching Stations are two Data Transfer Units (DTU). One DTU in the ECS simulates local launchers, and the other DTU, located in the CRG, simulates remote launchers which, in reality, may be in excess of 10KM from the rest of the fire unit.

In order to create the scripted targets for each scenario, the MFMS stimulates the RS by inserting the RF signals necessary to emulate an actual track of that type in the RS search sector.

When the radar is operating in "active radiate" mode, a combination of both MFMS-generated and real tracks will appear on the Patriot manstations (operator scopes). Visually, the graphic representations of MFMS tracks are no different than those of actual tracks. The operator makes the differentiation between real and simulated tracks by observing the Identify-Friend-or-Foe response of the track. Simply, a real aircraft will generate an interrogation response whereas the simulated aircraft will return no response.

Why Simulation?
With the testing of any new weapon system or upgrade to a fielded system, there come two inevitable requirements. First, testing must accurately mirror the system's operational environment, as it would exist in its wartime mission. Second, and perhaps more challenging, is that the first requirement must support the data collection required for system evaluation and the corresponding test schedule. In the case of the PAC-3 system, the absolute best test environment would be one of multiple live TBM, ABT, and ASM targets in flight under tracking and engagement by live PAC-3 missiles. This meets the first requirement as it mirrors Patriot operations in a wartime environment. The stumbling block is that costs would be monumental. With live missiles and aircraft flights as costly as they are, simulation is the natural alternative. Additionally, the continued proliferation of threat TBMs since Operation Desert Storm makes the development of accurate threat representative targets even more costly and challenging. The one simulation tool that effectively satisfies much of the two operational testing requirements for PAC-3 is the MFMS.

The Bottom Line
The basic costs incurred differ immensely for one live Patriot missile firing and the execution of one MFMS scenario. Based on PAC-3 Fiscal Year 2001 live fire test projected costs, the funding required to fire a single Patriot missile at White Sands Missile Range, New Mexico, is approximately $2 million. This includes firing range time, cost of the Patriot missile, and equipment maintenance primarily. Due to the proximity of White Sands and Fort Bliss, equipment transportation is not costly. Live missile firings at alternate locations, such as Kwajalein Missile Range in the South Pacific, require as much as three times the funding due to increased transportation and range operations costs. The table below show additional expenditures that cause overall costs to swell even further:

Additional Expenditures

Costs due to research and developmental testing of the target missile flight profile.

Requirement for multiple types of target missiles and target aircraft.

Extensive aircraft flying time requirements.

Significant wear-and-tear on the system as a result of live missile firings would mandate extra repair parts and maintenance personnel.

Increased time requirements due to multiple missile reloads.

Significant coordination requirements and many points of failure.

Based on PAC-3 LUT figures, the cost of one MFMS scenario with eight to 30 simulated target engagements is approximately $45 thousand. This includes the operational costs of the equipment and the creation, verification, and validation of the scenario for target adequacy. The table below lists the multiple factors that result in significant resource conservation.

Resource Conservation Factors

Much simpler and more cost-effective verification and validation of target flight profile for both missiles and aircraft; threat missile motion modeling is much easier than reproducing a real flying vehicle.

Significantly less system wear-and-tear and maintenance personnel requirements.

No physical reloads.

No flying time requirements .

The Outcome and Lessons Learned
The success of PAC-3 Limited User Test reinforces the strength of simulation in operational testing. The MFMS test tool allowed for required data collection and enabled the conservation of multiple resources. With test costs always being a factor throughout the projected fielding and evaluation of any system, funding consistently weighs heavily on the mind of any Test Officer. As in the case of PAC-3 and numerous other Department of Defense systems-under-test, exact wartime conditions may not always be feasible in terms of funding and manpower.

The MFMS has demonstrated a proven capability to correctly simulate the flight of threat aerial vehicles that, in turn, allows the operational tester to collect system performance data. Additionally, the only critical limitations of the MFMS are an incapability to simulate track clutter and an incapability to stimulate more than one fire unit at a time. Despite these few shortcomings, it is an outstanding tool that has lifted strains on funding, personnel requirements, and man-hours for the Patriot system. Its contributions will certainly allow for continued future usage as a paradigm of a successful operational testing alternative.