Mode II-II00 IFF indication was detected which was correlated with an Iranian F-14. This was reported throughout CIC over internal CIC voice circuits. Continuous MAD and IAD warnings were ordered at 30NM (5 total warnings on MAD and 4 total warnings on IAD). USS VINCENNES continued the surface engagement and experienced a foul bore in Mount 51. In order to unmask the after gun mount, full rudder (at 30 knots) was applied. This added to the increasing tension in CIC.
(c) At approximately 0651Z – As TN 4131 closed to 28NM, USS VINCENNES informed CJTFME that she had a closing Iranian F-14 which she intended to engage at 20 NM unless it turned away. USS VINCENNES requested concurrence. CJTFME concurred but told USS VINCENNES to warn the aircraft before firing. Warnings continued, but no response from TN 4131 was received, nor did it turn away.
(d) At approximately 0652Z – Warnings continued over both IAD and MAD. Still no response. Although TN 4131 reached the 20 NM point, the CO decided not to engage. The order was given to illuminate the contact with fire control radar. There were no ESM indications. TN 4131 was ascending through 10,000 feet.
(e) At approximately 0653Z – At 15-16NM, the last warning over IAD was given by USS SIDES to the aircraft bearing 204 degrees to USS VINCENNES, range 15.5 miles. During the last 30 seconds of this minute, the CO made his decision to engage TN 4131.
(f) At approximately 06:54, the CO turned the firing key. Two SM-2 Blk II missiles left the rails. They intercepted Iran Air Flight 655 at a range of 8NM from USS VINCENNES at an altitude of 13,500 feet.
E.POST INCIDENT INVESTIGATION
1. The focus of this investigation was on the key factors that figured in determination of what information was available to the Commanding Officer upon which to base his decision to engage TN 4131, the validity of that data, and what other factors entered into his decision making process. Essential to this determination was a detailed examination of the USS VINCENNES's data reduction tapes, which portray second-by-second the position, kinematics, IFF information and Link eleven (11) message flow of all contacts held by the USS VINCENNES's AEGIS Weapon System. Immediately following the incident, USS VINCENNES's AEGIS data recording tapes were transported to the Naval Surface Warfare Center, Dahlgren, Virginia, for data extraction and evaluation. The data extracted depicted the Iran Air Flight 655 flight profile from first detection to missile intercept. Further, the data allow reconstruction of all "button actions" by Command and Decision (C&D) console operators in CIC and the information available to them on their console readouts. Crucial to the investigation became close examination of the approximately 3 minute 45 second period just prior to the Commanding Officer's
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