H. T. KAUDERER

D

Air-Directed Surface-to-Air Missile Study Methodology

H. Todd Kauderer

uring June 1995 through September 1998, APL conducted a series of WarfareAnalysis Laboratory Exercises (WALEXs) in support of the Naval Air SystemsCommand. The goal of these exercises was to examine a concept then known as theAir-Directed Surface-to-Air Missile (ADSAM) System in support of Navy OverlandCruise Missile Defense. A team of analysts and engineers from APL and elsewhere wasassembled to develop a high-fidelity, physics-based engineering modeling processsuitable for understanding and assessing the performance of both individual systems anda “system of systems.” Results of the initial ADSAM Study effort served as the basis fora series of WALEXs involving senior Flag and General Officers and were subsequentlypresented to the (then) Under Secretary of Defense for Acquisition and Technology.(Keywords: ADSAM, Cruise missiles, Land Attack Cruise Missile Defense, Modelingand simulation, Overland Cruise Missile Defense.)

INTRODUCTIONIn June 1995 the Naval Air Systems Command

(NAVAIR) asked APL to examine the Air-DirectedSurface-to-Air Missile (ADSAM) System concept fortheir Overland Cruise Missile Defense (OCMD) doc-trine. NAVAIR was concerned that a number of impor-tant air defense–related decisions were being made onthe basis of results from medium- to low-fidelity models.They wanted APL to (1) analyze and assess air defensesystems and concepts using the most detailed and high-est-fidelity models, (2) examine the military capabili-ties and utility of the ADSAM concept using the resultsof this high-fidelity modeling, and (3) if warranted,transition the concept to an engineering-based project.

The ADSAM Study explored and demonstrated thetechnical and operational viability of the concept by

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• Developing an analytical methodology that tied to-gether a series of previously distinct, “stovepiped”high-fidelity engineering models into an integratedsystem that allowed the detailed analysis of a “systemof systems”

• Modeling, analyzing, and assessing the performancelimitations of component systems and the overallsystem using these high-fidelity system models

• Applying the APL Warfare Analysis Laboratory (WAL)Exercise (WALEX) approach to examine the opera-tional capability and viability of the proposed system

• Using the WAL, its display and visualization capabili-ties, and a seminar approach to convey analyticalresults and an operational understanding to high-leveldecision makers

HNS HOPKINS APL TECHNICAL DIGEST, VOLUME 21, NUMBER 2 (2000)

ADSAM STUDY METHODOLOGY

BACKGROUND

ConceptThe ADSAM concept was de-

veloped by the Navy in response tothe increased threat of enemyLand-Attack Cruise Missiles. Themajor limitation to naval OCMDis the inability of current ship-board radar to see low-flying tar-gets far inland owing to the Earth’scurvature and terrain blockage.Unlike ballistic missiles, which flyin a predictable trajectory, Land-Attack Cruise Missiles can alsochange course, making identifica-tion of their intended targets asuncertain as with engagement ofmanned aircraft. The ADSAMconcept uses airborne sensors todetect, track, and possibly illumi-nate these targets, passing sensordata via Cooperative EngagementCapability (CEC) data links toAegis ships off the coast. This al-

E-2C

CEC

CBA

CEC

Aegis

Aegis

Defendedarea

Figure 1. The goal of the ADSAM concept is to extend Fleet Area Air Defense overlandto defend ports, airfields, and U.S. and Allied expeditionary forces from cruise missile andaircraft attack. (CEC = Cooperative Engagement Capability, CBA = carrier-base aircraftused here for fire control.)

lows ships to engage enemy missiles even if the targetsgo undetected by their own onboard sensors (Fig. 1).

MethodologyThe various levels of modeling fidelity used in the

analytical approach described here can be likened to apyramid (Fig. 2). Knowing where the analyst is along theanalysis hierarchy is critical to understanding the levelof system fidelity that the process represents. At the topof the pyramid are campaign-level models that typifyfactors encompassing thousands of personnel and sys-tems over days, weeks, or months. Of necessity, theserepresentations are highly aggregated and are limited intheir ability to accurately model the detailed capabilitiesof individual systems. The next two levels—force-on-force and unit/systems modeling—exemplify the capa-bilities of the systems. The bottom tier of the pyramid,sometimes called the “fundamental” or “engineering”level, represents a higher level of fidelity for individualcomponents of the systems and for the system of systems.The ADSAM methodology resides at the bottom of thefundamental level, the foundation of the pyramid.

The ADSAM Study Team modeled the detect/con-trol/engage process in OCMD at the fundamental levelusing the highest-fidelity model of each componentavailable within the defense community. The NavalResearch Laboratory (NRL), for example, provided theNavy Airborne Surveillance Model. As part of theADSAM methodology, all models were operated bytheir owners to ensure that their design, assumptions,

JOHNS HOPKINS APL TECHNICAL DIGEST, VOLUME 21, NUMBER 2 (2

limitations, and operations were thoroughly understood(Fig. 3). Each model used also had Program Officeaccreditation for that component. This practice estab-lished the credibility and acceptance of the output.

Campaignanalysis

Force-level

analysis

Unit/systemsanalysis

Fundamental

Figure 2. Analysis hierarchy. Recognizing the analyst’s positionwithin the hierarchy is critical to an understanding of the level ofsystem fidelity that the process represents. The ADSAM method-ology resides at the bottom of the lowest level of the pyramid.

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H. T. KAUDERER

APL

Redtrajectories

(DTMA Model)

APL

Defendedassets

APL

Bluepositions

CSCI

TACSITs andquick look

CSCI

Bluesurveillance/FC

positioning(AIM Model)

APL

Platformintervisibility

(DTMA Model)

NAWC

Bluefighter

positioning

NRL

Airbornesurveillance

Pd and metrics

MIT/LL

Airborne FCPd and metrics

APL

Aegisradar track

(SPY firm track)

APL

JEFCSPd and metrics

(JLENS)

APL

JESSPd and metrics

(JLENS)

NAWC

Air-to-air fighterengagements

(IWARS Model)

APL

Compositetrack

(CEC Model)

APL

Engagementprediction(prototype

weapon control)

APL

Engagementcoordination

(DWC Model)

APL

Surface-to-airmissile analysis(SM-2 6-DoF)

NAWC

Air-to-airradar analysis

(WAAM)

APL

Displays(FTEWA/DOORS)

Figure 3. ADSAM 1998 analysis methodology. This simplified chart represents the data flow of high-fidelity models spread throughoutthe country. Model locations are indicated in red. (AIM = Air Intercept Missile, CEC = Cooperative Engagement Capability, DoF = degreeof freedom, DOORS = Distributed Object-Oriented Real-Time System, DTMA = Digital Terrain Mapping Application, DWC = DistributedWeapons Coordination, FC = fire control, FTEWA = Force Threat Evaluation and Weapons Assignment System, IWARS = IntegratedWarfare Architectures, JEFCS = Joint Elevated FC System, JESS = Joint Elevated Surveillance Sensor, JLENS = Joint Land-basedElevated Netted Sensor, MIT/LL = Massachusetts Institute of Technology Lincoln Labs, NAWC = Naval Air Warfare Center, Pd = probabilityof detection, TACSITs = tactical situations, WAAM = Weapons Analysis and Assessment Model; JEFCS and JESS comprise the APLrepresentation of JLENS.)

Results from each location were integrated through thedevelopment of standard formats for data exchange.Although previous uses of many of the models generallyinvolved stand-alone processing, outputs of each modelin ADSAM were modified to be compatible with inputsof the next model in the series. The physical data flowitself was performed via floppy disk and e-mail.

Using this modeling architecture, multiple scenariosfrom different theaters were developed and analyzed. Toexamine key system interactions, the 40- to 45-minflight time of each enemy missile was divided into0.25-s increments (yielding approximately 8 to 9000points of measurement for each representation of anenemy missile trajectory) to examine all factors impor-tant to the problem. Missile flight paths were modeledby APL staff knowledgeable about advanced cruisemissile systems. Since sensors would have to detect andtrack threats from continuously changing aspects, a fullaspect-dependent representation of the threats (Fig. 4)was developed in conjunction with the intelligencecommunity. This allowed a much greater validity inthreat representation than possible with a two-dimen-sional representation typical of higher-level models.

Surveillance radar modeling performed by NRL andMIT/LL system engineers and analysts provided inputsto the fire control modeling analysis. The fire controlprocess was the most complex. Seventeen critical fac-tors or events had to occur successfully, in the right

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sequence, to achieve intercept (see, e.g., Fig. 5). If anyone or more of the factors failed, then the attemptedintercept would fail (miss).

To make these extremely complex data more easilyunderstood, the Force Threat Evaluation and Weapons

Figure 4. Aspect-dependent differences must be reflected in therepresentation of the target being modeled when analyzing theview from surface platforms looking up at a target, aircraft lookingacross the target, or interceptors diving on the target. (a) Two-dimensional combined effect (low fidelity), (b) clutter Dopplernotch, (c) radar cross section, and (d) radar cross section withclutter Doppler notch.

(a) (b)

(c) (d)

HNS HOPKINS APL TECHNICAL DIGEST, VOLUME 21, NUMBER 2 (2000)

Figure 5. Engageability factors. Once surveillance tracking has transitioned to the firecontrol process, all of the factors shown must meet success criteria, in the right sequence,to allow target intercept. ADSAM modeled each process every 0.25 s through the 40- to 45-min flight time of the target. If at least one factor (component) failed, then the result wasdisplayed as a single vertical red line. Success was displayed by blue lines. A typical enemyflight would be represented by about 8 to 9000 lines.

Fire control radar (FCR) track initiation

FCR tracking Terrain blockage Pd Scan angle Radar Doppler

Handover Accuracy of seeker- received power density Seeker Doppler Heading error

CECcompositetracking

Threat launch Impact

Net engageability

(0.25 s intervals)

Surveillance

SM-2 missile launch, e.g.,kinematic range/no escape

FCR cued search

Midcourse commandguidance, e.g.,link blockage

Terminal homing Intercept point

Assignment (FTEWA) System was applied for displaydata during WALEXs. The system uses model data todrive dynamic three-dimensional displays, presentingthe modeled results to audiences in time-controllablepictures of a situation at 1-s increments. The FTEWASystem is currently being installed in the Fleet.

THE ADSAM STUDY METHODOLOGY,1995–1997

The first ADSAM Study began in the summer of1995. Its initial objectives were principally to studyconcept design and validation. Could a true system-of-systems engineering-level analysis be conducted usingpreviously stand-alone models of each component?Could results be understood and accepted by a widevariety of audiences, from engineers to operators, in-cluding representatives from different services? Couldhighly complex OCMD interactions and requirementsbe displayed so that all observers would understand theresults?

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ADSAM STUDY METHODOLOGY

Several representative advancedsystems concepts were modeledincluding an advanced E-2CHawkeye Navy airborne surveil-lance aircraft; a concept for an im-proved large, land-based airbornesurveillance aircraft; an airbornefire control illuminator supportingthe needs of naval semi-activeguided interceptors; and a singleAegis ship as the firing platform.The CEC process was assumed toallow connectivity of the requiredfire control data. During the earlyADSAM studies, engageability wasassessed using postflight analyses inwhich an intercept point was com-puted for each 0.25 s of target tra-jectory. The engagement processwas then worked backwards to seeif all necessary factors would havemet requirements, in the right se-quence, for a successful engage-ment. Results were then displayed,system component by component,over the timeline of the enemy tra-jectory, and factors enabling andlimiting the system of systems werehighlighted (Fig. 6).

Over the next 3 years, systemswere added to and deleted from thestudy as required to satisfy eachyear’s specific goals. In 1996, Navy-unique systems were examined ingreater detail. In 1997, under the

sponsorship of the J8 section of the Joint Staff, the firsttrue examination was conducted of a scenario employ-ing Joint systems such as the Air Force AWACSaircraft, the Army Patriot SAM systems, and Navysystems. Modular capabilities of the methodology pro-vided great flexibility while maintaining the credibilityof the engineering-level analysis.

The WALEX process was used successfully to presentobjectives and complex study results to a wide varietyof participants. Attendees were then given the oppor-tunity to provide their responses, express their con-cerns, and offer guidance to the sponsors. Not all issueswere immediately resolved in the WALEXs, but direc-tion was provided where additional study and require-ments definition were needed.

Also during this period, the requirement to replacethe assumption of CEC capability with a comparablehigh-fidelity model of the CEC composite track func-tion led to the development of a model that could takeinputs from other high-fidelity models. In many waysthis was the most complex effort developed for the

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H. T. KAUDERER

Figure 7. CEC Composite Track Filter Model. The critical factor in the ADSAM process isthe requirement for composite track generation through the CEC System. In this study themodeled surveillance results from each sensor were provided in the standard AssociatedMeasurement Report (AMR) format to the composite track filter. The process then appliedthe same algorithms as those used in the Fleet to generate the composite tracks. (Blueindicates that the effect was incorporated into the model.)

Figure 6. Representative data from a postflight analysis display. Once the process wasmodeled, the success and contribution of each component in the system (see, e.g., Fig. 5)could be displayed and compared.

CBA terrain blockage

CBA radar Doppler

CBA update probability

CEC track probability

Components

High update rate track

Kinematic range

Uplink blockage

Handover

Seeker Doppler

Net engageability

Threat launch Impact

ADSAM process. Prior to this effort and during its development, CECmodeling had relied on processing the actual recorded radar measurementdata from sea-based, land-based, and airborne sensors. Using the samealgorithms to determine CEC composite track probability as operationalunits, the new CEC model allowed the modeled data to be input from eachProgram Office–approved sensor model and provided useable compositetrack information to begin the modeling of the engagement process. Figure7 indicates the functions in the CEC process, with those modeled forADSAM shown in blue. Additional functions not yet modeled may beadded in the future.

Gridlock/alignment

Modeledprocesses

Trackmanager

DataDistribution

System

CECengagement

decision

Display

Combatsystem

adaptive layer

E-2Csensor

CBAsensor

Local sensoradapter layer

Local sensoradapter layer

Local sensoradapter layerJESS

Radarhits

Local AMRsTrack state

vector

Local AMRsTrack state

vector

Gridlock padsNavy data

AMRs

Track statusTrack state

vector

Remote AMRsLocal AMRs

Trackstatevector

CEC composite track

248 JOHNS HOPKINS APL TECH

Normally the first WALEX audi-ence in a yearlong study cyclecomprised naval O-6/Captain-levelAction Officers. An O-6/Captain/Colonel-level Joint Action OfficerWALEX followed. O-6-level WAL-EXs focused on technical aspects ofthe analysis, component represen-tations and validations, technicalramifications, and initial operation-al considerations. After the O-6 ex-ercises, a series of naval and jointFlag/General Officer WALEXs wasconducted, for which the focusshifted from technical issues tooperational issues such as com-mand responsibilities, interserviceinteroperability, and rules of en-gagement. A typical issue raised byat least one General Officer, how-ever, was that even though it waspossible for the Navy to now shootthat far inland, who was going to letthem do so? This concern led to theidentification of (1) critical issuesin Joint Air Defense coordinationpolicies and procedures and (2)concepts of Area and RegionalAir Defense, among others. Even-tually these issues were incorpo-rated into other WALEXs, forexample, by the Navy to developArea Air Defense doctrine and bythe Joint Theater Air and MissileDefense (TAMD) Office to devel-op a prototype Joint TAMD doc-trine. Subsequent Flag briefingswere provided to senior Navy andJoint audiences, up to and includ-ing the (then) Under Secretary ofDefense for Acquisition and Tech-nology, Paul Kaminski.

THE ADSAM/NAVYOCMD STUDYMETHODOLOGY, 1998

Two advances in analysis meth-odology were added during the1998 ADSAM Study cycle. First, itwas expanded to consider threepossible Aegis shooters, each withthree different weapon options(i.e., concepts of interceptors).This required the development of aDistributed Weapons Coordination

NICAL DIGEST, VOLUME 21, NUMBER 2 (2000)

ADSAM STUDY METHODOLOGY

Figure 8. Predicted engageability pro-cess. Unlike postflight analysis (see Fig.6), the need for engagement predictionrequired the study team to compute theprobability of successful intercept forevery point to which the target could moveduring the flight time of the interceptor.This was done every 0.25 s for approxi-mately 90 potential intercept points. Fac-tors considered here are, for example,handover uncertainty, seeker-receivedpower density, seeker Doppler, spilloverpower density, and rear reference signal.

(DWC) process, beginning withthe formulation of an algorithm toestimate the probability of success-ful intercept for each type of weap-on from each shooter at any giveninstant (Fig. 8). Typical results fromthe algorithm for just one enemymissile are shown in Fig. 9. Thiswas followed by a recommendationof which ship should shoot, withwhich type of weapon. The algo-rithm also allowed the analyst toidentify why the recommendationwas made (Fig. 10).

Targettrack

history

CurrentCurrenttartarggetet

positionposition

FutureFuturetartarggetettractrackk

Arc of possible targetposition estimates(every 1° up to ±45°from straight line)

Predictedengageability

factors

Straight line targetposition estimate

JOHNS HOPKINS APL TECHNICAL DIGEST, VO

Figure 9. Engageability prediction: representative data for one trajectory. Once com-puted for each trajectory (and with each intercept option having different guidance choices,denoted by GC), and for each potential launch platform, the data were compared to identifywhere intercept success was greatest and where DWC was required.

Figure 10. Preferred shooter recommendation/typical criteria prioritization. Once theengageability prediction process was completed, points indicating the simultaneousavailability of more than one shooter or weapons option required a procedure to recom-mend which ship should shoot, with which weapon, and why. The prioritized set of criteriashown was developed and used for the 1998 ADSAM Study. This was not an attempt tospecifically set the criteria for all situations, and further work is ongoing to better refine theprocess and its level of flexibility.

ADSAM - GC#1

ADSAM - GC#2

Local engage

ADSAM - GC#1

ADSAM - GC#2

Local engage

ADSAM - GC#1

ADSAM - GC#2

Local engage

Cruiser 1

Cruiser 3

Cruiser 2

Launch ImpactTime in 0.25-s increments

90–100% 60–89% 20–59% 1–19% 0%

Y

Sequential preferred shooter test(test all remaining candidates at each step)

• Engagement type “Autonomous”• Highest predicted engageability•“No escape” from missile range• Earliest intercept•“Entering” missile range• Inventory (missiles expended + committed)• Missile guidance type• Coin toss

Number ofremainingcandidates

>1 0 1

Passremaining

Skip this test

Per

form

nex

t tes

t

Check resultat each step

Candidates>1

Infighterzone?

Inmissilerange?

Predictedengageability

success >threshold?

Y

N

N

Y

N

Y

N

Initiateengagement

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H. T. KAUDERER

The DWC process was initiated if the engagementprediction algorithm indicated that, at specific 0.25-sintervals, multiple opportunities for successful inter-cept existed simultaneously. These ranged from oneshooter having multiple weapon choices to all threeshooters with three successful weapons options. Oncethis situation occurred, a prioritized list of decisioncriteria was used for the recommendation (Fig. 10). Forthe 1998 study cycle, a representative list of decisioncriteria was developed using such items as “highestprobability of successful engagement,” “first intercept,”and “highest level of magazine remaining.” It was rec-ognized that future analyses and DWC developmentwould have to be able to examine results using differentor reprioritized criteria and that the on-scene com-mander would require this same flexibility.

Results provided numerous conditions where nonin-tuitive recommendations were made. When analystsexamined the recommended shooters, one shooter wassometimes selected over another (at half the range of thefirst shooter) because it had less of a problem with seekerDoppler. In another case, a shooter was selected to firebehind itself because the intercept prediction indicateda higher probability of successful intercept. These kindsof decisions may not have been made by a commanderoperating unassisted in a quick-response situation.

Another advance in the 1998 ADSAM/OCMDStudy was inclusion of the air-to-air component ofTAMD. With participation by NAWC, China Lake,California, sensor pictures derived in the ADSAM

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modeling process could be provided to the center’shigh-fidelity models of aircraft, airborne fighter radar,and air-to-air interceptor to represent their engage-ment. Results were returned to APL for display andinclusion with surface-to-air results. The air-to-aircomponent, although not integrated into the DWCprocess in 1998, is expected to be integrated in futurephases of the ADSAM Study.

THE FUTURE OF THE ADSAMMETHODOLOGY

The ADSAM methodology is modular and hasbeen adapted in each annual cycle to address sponsorrequests for systems analysis. For example, in 1997under Joint Chiefs of Staff (JCS)/J8 sponsorship, sys-tems such as Patriot and Aerostat/JLENS were exam-ined. The results were used in a JCS/J8 OCMD Study.Future ADSAM analysis is expected to add AWACSand expanded air-to-air models, and to increase theparticipation of Patriot, JLENS, and other air defensesystems. The ADSAM methodology can also be usedin TAMD analyses through the addition of all-serviceor multiservice Ballistic Missile Defense systems.

Finally, while the methodology has been used toexamine air defense problems, the basic concept can beapplied to others like anti-submarine, anti-surface,strike, and electronic warfare to provide the true sys-tem-of-systems physics-based, high-fidelity, credibleresults needed in those fields.

THE AUTHOR

H. TODD KAUDERER has a B.S. in industrial engineering from NorthwesternUniversity, an M.S. in management from the Kellogg School at NorthwesternUniversity, and M.S. in strategic intelligence from the Defense IntelligenceCollege, and an M.S. in public administration from USC. He is currentlycompleting his doctoral dissertation in public administration, which concerns theuse of WALEXs in military acquisition programs. He served as a surface warfareand intelligence officer in the Navy from 1976 to 1984. From 1984 to 1990 Mr.Kauderer was the founding Director of Operations of SATELLEASE, Inc., aprovider of national and worldwide communications networks. He joined APL in1991 and is a member of the Principal Professional Staff in the JWAD JointInformation Analysis Group. He has been the Study Director for ADSAM sinceits inception in 1995. He is also currently a Commander in the Naval Reserveattached to the National Reconnaissance Office. His e-mail address istodd.kauderer@jhuapl.edu.

NS HOPKINS APL TECHNICAL DIGEST, VOLUME 21, NUMBER 2 (2000)