In January 1996, the Navy and the Army demonstrated advanced, experimental capabilities in Cruise Missile Defense (CMD). In the CMD Phase I Advanced Concept Technology Demonstration (ACTD), also known as "Mountain Top", surface-to-air missiles were launched from an AEGIS cruiser to engage sea-skimming cruise missile test targets well beyond the ship's radar horizon. Concurrently, an Army PATRIOT missile battery conducted simulated engagements and missile seeker tests that demonstrated a robust potential capability to engage cruise missiles beyond line of sight of land based sensors.

Approved by the Deputy Under Secretary of Defense (Advanced Technology) in May 1994, the CMD ACTD Phase I was a joint Army and Navy effort led by the Navy. The Chief of Naval Research, Rear Admiral Marc Pelaez, was the ACTD executing agent and Dr. Eli Zimet, Head of the Special Programs Department (Code 35) of the Office of Naval Research (ONR), was the overall demonstration manager. Rear Admiral Tim Hood, Program Executive Officer (PEO) for Theater Air Defense, and Mr. Mike O’Driscoll, Cooperative Engagement Capability (CEC) program manager, were responsible for coordinating Navy activities. Brigadier General Dick Black, PEO for Missile Defense, and Mr. Dale Moore, Army Mountain Top Experiment (AMTE) program manager, were responsible for coordinating Army activities. The ACTD user sponsor and operational manager was the Commander-in-Chief, United States Pacific Command, Camp Smith, Oahu, Hawaii. The demonstration was conducted at the Navy’s Pacific Missile Range Facility (PMRF), Barking Sands, Kauai, Hawaii and surrounding sea areas and airspace.

The focus of this ACTD was the detection of over-the-horizon cruise missile targets by an elevated sensor and target engagement by surface-based (sea and land) air defense systems. In practical terms, the extended horizon engagement concept involves deploying an airborne platform with a new surveillance and tracking radar to detect low-flying cruise missiles while they are still far beyond the horizon of protected areas and defending shooters. The airborne radar is envisioned to provide precision radar data for guidance of surface-to-air missiles launched from ships and land-based missile batteries to intercept cruise missile targets beyond the firing ship's horizon or battery’s line of sight.

One of the technical challenges of achieving this capability was to develop a "networking architecture" to allow the individual radars and weapons systems onboard the firing ship or battery and airborne surveillance/tracking sensors to operate as a single composite air defense system. The networking architecture must meet the very stringent requirements necessary to transfer radar and missile status data with high accuracy and precise timing to provide for interceptor missile control and homing. This networking requirement was met by the Navy's Cooperative Engagement Capability (CEC). CEC provides an identical, real time, fire control quality picture of the battle space as though it were viewed through the collective eyes of all participants in the CEC network.

Other technical challenges were modifications to surface-to-air missile performance, missile control, and airborne radar. Required changes to Navy STANDARD missile terminal homing performance were incorporated in several of the latest SM-2 Block IIIA missiles specially modified for this experiment. At this stage in their development, the representative airborne elements have not been installed in aircraft. Representative airborne elements were installed on Kokee mountain in Kauai, Hawaii - thus the name "Mountain Top" - as a surrogate aircraft at 3800 foot elevation. The Radar Surveillance Technology Experimental Radar (RSTER) used in this demonstration was developed by the Navy in conjunction with the Defense Advanced Research Project Agency, features advanced signal processing techniques, and was paired with an ADS-18S advanced phased array antenna mounted atop a 100 foot tower. A Navy Mark 74 Tartar missile fire control system used for target tracking and illumination was collocated with the CEC antenna on an adjacent tower. Equipment for these sensors was housed in buildings at the Kokee site.

Navy Mountain Top culminated in missile firing tests conducted on 20-21 January 1996. The AEGIS cruiser, USS Lake Erie (CG-70), fired four STANDARD missiles and achieved four target kills at ranges more than three times greater than typically achievable with today's deployed systems.

USS Lake Erie, equipped with CEC for this demonstration, was stationed approximately 30 miles downrange from the Kauai shore. A typical firing scenario began when a sea-skimming target launched from PMRF, was flown out beyond radar range, and turned back toward the ship or toward shore. The developmental radar at the Kokee site detected the target and provided tracking data to USS Lake Erie via CEC. USS Lake Erie evaluated the threat, completed fire control solutions, and ordered the target engaged while it was still well beyond the ship’s AEGIS SPY-lB radar horizon. That caused CEC to automatically cue the Mark 74 system tracking radar/illuminator at the Kokee site to acquire the target and provide radar position measurement data directly to the AEGIS Combat System via CEC. AEGIS used this remote composite track data for initialization, launch and midcourse guidance of a STANDARD missile. When the missile passed beyond the ship's radar horizon it was guided to the target by reflected signal energy from the tracking radar illuminator at Kokee. Because target tracking and terminal homing illumination were provided by the surrogate aircraft via CEC, the SM-2 could intercept a low-flying target at long range, thus dramatically extending the air defense horizon.

The Navy achieved its Mountain Top objectives with all low-flying targets successfully engaged. The critical implication to future warfighting is the Navy's potential ability to project its power inland and defend forces ashore against low flying overland cruise missiles using existing AEGIS capabilities and advanced aircraft systems to greatly extend the ship's horizon .

The Army Mountain Top Experiment (AMTE) also used surveillance and fire control data from the elevated sensors at the Kokee site. An Army PATRIOT battery, sited at the Department of Energy administered Kauai Test Facility located at PMRF, developed fire control and acquisition solutions on targets using Mark 74 track data transmitted from the CEC processor at Kokee via the Joint Tactical Information Distribution System (JTIDS). Since development of the PATRIOT Advanced Capability-3 (PAC-3) surface-to-air missile is only in the beginning stages, the AMTE team combined captive carry tests (CCT), consisting of a prototype PAC-3 seeker suspended from a test aircraft, with a real-time, high fidelity virtual engagement interceptor simulation called the Virtual Engagement Simulation Tool or "VEST". By combining the high fidelity attributes of both test tools, it was possible to perform a real-time, high fidelity, end-to-end demonstration without requiring a "Live-Fire" test. The AMTE is very possibly the first program to synchronize a high-fidelity simulation and CCT with a tactical air defense system in a real-time test environment.

The AMTE program was completed on 26 January 1996. A combined total of 112 CCTs and virtual engagements were conducted, of which, 101 were classified as "successful", 2 classified "failures", and 9 classified as "no tests", for a spectacular 98% success rate. The AMTE proved that cruise missiles can be engaged beyond the line-of-sight of a ground-based air defense system sensor, and that this concept can be applied to battalion-based air defense doctrine, and systems that employ active-seeker interceptors.

Following completion of the Navy and Army technology demonstration, an Enhanced Joint Exercise was conducted. The USS Lake Erie, Army PATRIOT Battery, and mountain top sensors were joined by additional units from the Navy, Air Force, and Marine Corps to conduct a series of scenarios to collect data and demonstrate joint theater air and CMD operations. Two CEC-equipped AEGIS cruisers, USS Anzio (CG-68) and USS Cape St. George (CG-71) from the Atlantic Fleet, arrived near Kauai to join with USS Lake Erie in participating with the Army, Air Force, Marine Corps, Hawaii and New Mexico Air National Guard, and US Customs Service units, in a series of joint-service littoral operational scenarios including more cooperative engagement SM-2 firings. A Marine Corps HAWK battery fired missiles to successfully engage several targets based on cueing of the fire control illuminators by the AEGIS SPY radars via CEC. An Air Force AWACS testbed aircraft collected radar data against the mountainous Kauai coastal terrain in conjunction with a CEC-equipped US Customs Service radar aircraft. Finally, as part of a separate demonstration effort, experiments were performed with a 32 meter tethered aerostat that provided infrared tracking data and also relayed CEC track data to cue the Hawk batteries.

The highly successful Mountain Top ACTD and Enhanced Joint Exercise will be further evaluated to refine the development effort and move ahead towards achieving the vision for joint, extended-horizon cruise missile defense.

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Author: Dr. Eli Zimet
Revised: 1.24.97