The above photograph is of the U.S.S. Vincennes, a Ticonderoga Class missile cruiser incorporating the Aegis defense system.
The U.S.S. Vincennes is infamous as the ship which mistakenly shot down an Iranian Airbus jetliner in 1988, lending credibility to the suggestion that a similar accident might have occurred to TWA Flight 800.
It's important to recall that the Aegis system is independent of the type of ship. Other classes of ships, including the more modern Arleigh Burke class ships, also use the Aegis system.
The above photograph is of the U.S.S. Normandy, also a Ticonderoga Class missile cruiser incorporating the Aegis defense system.
This is the ship which was 185 miles from the crash site.
Aegis refers specifically to the combination of the SPY-1D synthetic aperture radar system and various munitions designed to interface with it, most notably the SM-1 and SM-2 "Standard" semi-active radar homing missiles. Closer in, the Aegis radars select targets for and interface with naval artillery and the Phalanx CIWS.
Launch of a Standard from an Arleigh Burke. Note the octagonal phased antenna array for the Aegis/Spy radar at lower left.
Unlike traditional radars, which use massive moving dishes to focus the radar beams, the SPY-1D radar system uses four flat planer arrays which steer the beams electronically under computer control. Because the planar arrays do not physically move, the radar beams may be moved from point to point in an instant. This allows the system to keep multiple targets painted with target designation beams.
In operation, a target is designated by repeatedly painting it with a radar beam which is modulated with an identifying code. The missile launched for that target is programmed to react only to the radar echos with that identifying code.
This allows the Aegis to manage up to 22 missiles in the air with 4 in "terminal phase" (which requires more rapid painting of the target).
The $500 million Aegis radar and weapons control system was tested by setting it up near Exit 4 of the New Jersey Turnpike where it merely watched the local general aviation traffic. It's first "active" test involved the shooting down of 10 out of 11 drones, all on courses known in advance to the system operators.
Deployed on the Ticonderoga Class ships, the Aegis first saw combat in the Persian Gulf in 1988, where it locked onto an Airbus 300, but mis-identified it as the much smaller F-14. The Aegis also reported that the target was descending even though the airbus was, in fact, climbing, and erred on the altitude by 4000 feet. The combination of all these errors convinced the Captain that his ship was under attack, and the Airbus was shot down.
DDG 51 CLASS ADVISORY NR 16-94 AEGIS BASELINE 4 CND HOT RECOVERY PROCESSING-CND OPERATIONAL ISSUE REF/A/USS HUE CITY/242253ZJAN94/-/NOTAL// REF/B/RMG/NSWC DD/031750ZJUN94/-/NOTAL// REF/C/RMG/NSWC DD/091620ZAUG94/-/NOTAL// NARR/REF A REPORTS INABILITY TO MANUALLY ENGAGE A SPY-1 TRACK. REF B RESPONDS TO REF A. REF C REPORTS BASELINE 5 COMPUTER PROGRAM PLAN.// RMKS/1. THIS CLASS ADVISORY DESCRIBES AN AEGIS BASELINE 4 COMMAND AND DECISION (CND) SYSTEM LOGIC PROBLEM THAT CAN CAUSE A FAILURE TO PROPERLY ENGAGE A TARGET. THIS ADVISORY PROVIDES INFORMATION NECESSARY TO DETERMINE WHEN THE PROBLEM OCCURS AND DESCRIBES WORKAROUNDS PENDING DELIVERY OF THE AEGIS WEAPON SYSTEM BASELINE 5.0 COMPUTER PROGRAMS WHICH CORRECT THE PROBLEM. 2. BACKGROUND. THE SYMPTOMS OF THIS PROBLEM WERE FIRST OBSERVED IN USS HUE CITY (REFS A AND B REFER). IF AN OPERATOR PERFORMS A MANUAL CORRELATE OR INTERCHANGE ACTION (EACH OF WHICH MODIFY THE CONTROL TRACK STORAGE LOCATOR (CTSL)/CONTROL GROUP TRACK NUMBER (CGTN) PAIRING), AND A CND HOT RECOVERY OCCURS, THE CTSL/CGTN PAIRING WILL BE LOST WITHIN CENTRAL TRACK STORES. THIS PAIRING LOSS WILL PREVENT PROPER ENGAGEMENT PROCESSING. A. HOT RECOVERIES OCCUR FOR A VARIETY OF REASONS. THEIR OCCURRENCE IS TRANSPARENT TO CIC OPERATORS, EXCEPT FOR THE CPIS SUBMODE. CPIS WILL RECEIVE A CND HOT RECOVERY TUTORIAL AND MUST NOTIFY THE APPROPRIATE OPERATORS (I.E. CSC, AAWC). B. THE FOLLOWING PARAGRAPHS DESCRIBE THE SPECIFICS ASSOCIATED WITH MANUAL CORRELATION AND INTERCHANGE ACTIONS: (1) CORRELATE. MANUAL CORRELATIONS OCCUR WHEN A SPY TRACK IS HOOKED AND A TRACK BEING REPORTED BY ANOTHER SOURCE IS BALL-TABBED AND AN OPERATOR DEPRESSES THE CORRELATE VAB. CND DOES NOT SAVE THE NEW CTSL/CGTN PAIRING TO THE BACKGROUND COPY FOLLOWING THE CORRELATION. WHEN CND PERFORMS A HOT RECOVERY, THERE IS NO VALUE RECOVERED IN THE CGTN FIELD ASSOCIATED WITH THE CTSL. (A) IMPACT. WHEN THE HOT RECOVERY OF CND IS PERFORMED AND THE CTSL/CGTN PAIRING IS LOST, ENGAGEMENTS WILL BE DISALLOWED BECAUSE CND DOES NOT KNOW THAT SPY HOLDS THE TRACK. THIS APPLIES TO DOCTRINE-INITIATED AS WELL AS MANUALLY-INITIATED ENGAGEMENTS. (B) OPERATOR OBSERVABLE. WHEN TAKING ENGAGE SM ACTION ON A FIRM SPY TRACK, THE OPERATOR WILL RECEIVE NOT HELD BY SPY-REQUEST SENT TUTORIAL. FIRM TRACK WILL STILL EXIST IN SPY. NOTE: OPERATORS WILL NOT RECEIVE A TUTORIAL IN THE EVENT OF A DOCTRINE-INITIATED ENGAGEMENT. (2) INTERCHANGE. THE TRACK INTERCHANGE FUNCTION PERMITS AN OPERATOR TO CHANGE THE CTSL/CGTN PAIRINGS FOR TWO TRACKS AND IS SUBJECT TO STRICT LEGALITY CONDITIONS (I.E. INTERCHANGE IS NOT PERMITTED ON TWO ENGAGED TRACKS). CND DOES NOT SAVE THE NEW CTSL/CGTN PAIRINGS TO THE BACKGROUND COPY FOLLOWING AN INTERCHANGE ACTION. WHEN AN INTERCHANGE IS PERFORMED, POSITIONS AND CGTNS ARE SWAPPED WHILE CTSLS REMAIN THE SAME. WHEN CND PERFORMS A HOT RECOVERY, THE OLD CTSL/CGTN PAIRING IS IMPROPERLY RECOVERED. A SUBSEQUENT ENGAGE ACTION WILL RESULT IN CND ENGAGING ONE TRACK WHILE WCS WILL BE REQUESTING INFORMATION FROM SPY ON ANOTHER. (A) IMPACT. WHEN A HOT RECOVERY OF CND OCCURS AND THE OLD CTSL/CGTN PAIRING IS RECOVERED, ENGAGEMENTS WILL CONTINUE TO BE ALLOWED, BUT IF THE CND HOT RECOVERY OCCURS PRIOR TO AN ENGAGEMENT, WCS WILL BE GIVEN THE OLD CGTN AND WILL THEREFORE REQUEST INFORMATION FROM SPY ON THE INCORRECT TRACK. NOTE: IF THE ENGAGEMENT COMMENCES PRIOR TO THE HOT RECOVERY OF CND, WCS WILL CONDUCT THE ENGAGEMENT ON THE CORRECT TRACK. (B) OPERATOR OBSERVABLE. THE OWNSHIP ENGAGEMENT STATUS SUMMARY CRO WILL REFLECT THE CORRECT CTSL. THE OPERATOR WILL SEE MISSILE FLY-OUT AND INTERCEPT POINT DISPLAYED FOR AN INTERCEPT TO THE INCORRECT TARGET. WCS ENGAGEMENT AND MISSILE CONTROL FUNCTIONS WILL BE BASED ON THE PREVIOUS (IMPROPER) CGTN AND, THEREFORE,MISSILE GUIDANCE WILL BE TO THE INCORRECT TRACK. 3. ACTION. FOLLOW THE WORKAROUND STEPS FOR GUIDANCE REGARDING THE MANUAL CORRELATE AND INTERCHANGE PROBLEMS. A. CORRELATE. AS A TEMPORARY MANUAL CORRELATE SOLUTION, UPON RECEIPT OF A NOT HELD BY SPY-REQUEST SENT TUTORIAL, THE OPERATOR SHOULD VERIFY THROUGH THE RSC THAT THE TRACK IS, INDEED, AN ACTIVE SPY TRACK. IF SO, THE PROBLEM CAN BE ALLEVIATED BY MANUALLY DROPPING THE TRACK IN QUESTION. CND WILL NOT NOTIFY SPY OF THIS DROP TRACK ACTION SINCE NO CGTN IS ASSOCIATED WITH THE TRACK. SPY WILL CONTINUE TO REPORT THE TRACK TO CND, AND CND WILL INITIATE A NEW TRACK WITH THE PROPER CGTN. THE ENGAGEMENT MAY THEN PROCEED. B. INTERCHANGE. THE OPERATOR CAN RESOLVE THIS WITH A SECOND INTERCHANGE (FOLLOWING THE HOT RECOVERY). THIS FORCES CND TO SEND A CTSL ASSIGNMENT MESSAGE TO WCS, WHICH CORRECTS THE DISPARITY BETWEEN CND AND WCS. 4. FOR COMNAVSURFLANT/COMNAVSURFPAC - RECOMMEND DDG 51-58 (WITH BASELINE 4.2 COMPUTER PROGRAM) BE TASKED TO ADHERE TO PARA 3 GUIDANCE. ORIG UNDERSTANDS THAT THE WORKAROUNDS PROVIDED ARE CUMBERSOME AND UNACCEPTABLE IN A TACTICAL ENVIRONMENT AND RECOMMENDS THAT MANUAL CORRELATION AND INTERCHANGE ACTIONS BE TAKEN WITH GREAT CARE WHILE OPERATING WITH THE AWS BASELINE 4.2 COMPUTER PROGRAM. CPCR 82469, CGTN NOT RECOVERED ON HOT START, DOCUMENTS THIS PROBLEM. IT IS APPLICABLE ONLY TO BASELINE 4.2, AS THIS PROBLEM WAS FIXED BY INCORPORATION OF THE FIX FOR CPCR 95192 IN THE AWS BASELINE 5.0 COMPUTER PROGRAM (REF C REFERS). 5. CANCELLATION. THIS CLASS ADVISORY WILL BE CANCELLED UPON DELIVERY AND INSTALLATION OF AWS BASELINE 5.0 COMPUTER PROGRAM TO SHIPS HAVING THE AWS BASELINE 4.2. 6. ORIG POC IS N. SMITHSON, PMS400F511, DSN 332-5981 OR COM (703)602-5981 EXT 133. TPOC IS CDR JEFFERY W. WILSON, PMS400B30A, DSN 332-7090 OR COM (703)602-7090 EXT 222.//
05/94 First Baseline 5 Phase I AEGIS Weapon System (for DDG 65) pull-the-plug event at Production Test Center in Moorestown, NJ. 10/16/94 Baseline 5 Phase II Demonstration at CSED Site. 09/11/95 Baseline 5 Phase III Demonstration at CSED Site. 04/10/96 Baseline 5 Phase IIIB Demonstration at ACSC/Wallops Island, VA. 04/16/96 Baseline 5 Phase IIIR Demonstration at CSED Site.
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