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.
From HTTP://www.spear.navy.mil/ise/ddg/ddg_16-94.html
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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