# Formal Investigation into the Circumstances Surrounding the Downing of Iran Air Flight 655 on 3 July 1988/Second Endorsement

OFFICE OF THE CHAIRMAN THE JOINT CHIEFS OF STAFF WASHINGTON, D.C. 20301-5000
CM-1485-88 18 August 1988
SECOND ENDORSEMENT on Rear Admiral Fogarty's ltr of 28 July 1988
| From: | Chairman, Joint Chiefs of Staff |
| To: | Secretary of Defense |
| Subj: | FORMAL INVESTIGATION INTO THE CIRCUMSTANCES SURROUNDING THE DOWNING OF IRAN AIR FLIGHT 655 ON 3 JULY 1988 (U) |
* (U) The downing of civilian Iran Air Flight 655 on 3 July was a tragic and regrettable accident and, as is so often the case in a combat environment, there were a number of contributing factors. It is first important to put the events of that day in the local context.
* (U) The U.S. Government committed naval forces to the convoying of American flag tankers in the spring of 1987. From the outset, the Administration emphasized that while our forces could achieve this mission, it would involve risks and uncertainties. This prediction was borne out by several incidents, e.g., the indiscriminate laying of Iranian mines, the Bridgeton explosion, the STARK tragedy, the SAMUEL B. ROBERTS striking a mine, the capture of the Iran Ajar, Iranian firing on U.S. helos, and the incidents of April 18 when Iranian ships and aircraft attempted to damage U.S. units. Throughout this period and especially in the wake of the above events, the Government of Iran issued inflammatory statements threatening retaliation against American personnel and interests. Reinforcing the high level of tension, both Baghdad and Teheran have continued to attack unarmed merchant ships, the former with aircraft and the latter with small boats, ships and aircraft. Iranian assaults have been largely concentrated in the southern gulf and on occasion have taken place in the presence of foreign warships. (U) As a result of the STARK incident, our commanders were given a revised set of ROE which clarified their authority to take positive protective measures when hostile intent was manifested. It was emphasized that they do not have to be shot at before responding and that they have an unambiguous responsibility to protect their units and people. To facilitate these measures a Notice to Airmen was reviewed and reissued in September 1987. It advised all nations who operate aircraft in the Persian Gulf region that U.S. Navy ships were taking additional precautions. In particular the need for aircraft operating in those waters to be prepared to identify themselves on specific circuits and to state their intentions was emphasized. Additionally, they were advised that failure to respond to requests for identification, as well as operating in a threatening manner, could place aircraft at risk by U.S. defensive measures. These practices, despite some grumbling, have been generally accepted in the Gulf. Unfortunately, few commercial airlines saw fit to reroute their aircraft or to make any other significant allowances for the hostile environment. Still, it is clear that all concerned were aware that U.S. ships were deployed in the area and that those units fully intended to defend themselves when necessary. ​( ) For several months preceding the Air Bus shootdown, the U.S. had received reports of Iranian efforts to improve their ability to attack U.S. men-of-war. These have included attempts to outfit both aircraft and small boats for suicide assaults, to reconfigure F-4s, F14s, and other types aircraft to carry a variety of air-to-surface missiles, and to develop small boat "swarm" tactics which could break through a warship's defensive gunfire. Special occasions, such as Moslem or American holidays, inevitably precipitated intelligence reports that the Iranians were preparing a particular operation directed at Americans. In fact, we had been warned of the possibility of some type of unusual assault on the 4th of July weekend. (U) Of especial interest was the recent shift of Iranian F-14's from Bushehr to Bandar Abbas. In the few days preceding this incident several F-14 flights, operating from Bandar Abbas, took place in the southern Gulf. On 2 July, USS HALSEY had to warn away a potentially threatening Iranian F-14. (U) Upon arrival in the region every unit, including VINCENNES, was briefed on our past experience, the current ROE, and most recent intelligence. It is fair to say that incoming ships approach Gulf operations aware of the uncertain environment and with an appreciation of the reed for vigilance. Similarly, they have been impressed with their responsibility to defend themselves in a forehanded manner. Those thoughts are constantly on the minds of every commander and crew serving in the Gulf.
* (U) The events that led to the tragedy on 3 July were typical of the everyday patterns in the Gulf. On 2 July, Iranian gunboats in the Gulf had positioned themselves in the western approaches to the Straits of Hormuz and were challenging transiting merchantmen. MONTGOMERY was located sufficiently close to a ship attack in progress to respond to a request for distress assistance and to fire warning shots to ward off IRGC units attacking a merchant vessel. (U) On the morning of 3 July, MONTGOMERY observed seven IRGC small boats approaching a Pakistani vessel. The number shortly thereafter grew to 13 and they began to challenge nearby merchantmen. VINCENNES was ordered to the area to support MONTGOMERY and launched a helicopter to reconnoiter the scene. In the process the helicopter was fired upon. VINCENNES and MONTGOMERY closed the general areas of the small boats. Two of the boats turned toward VINCENNES and MONTGOMERY while the others began to maneuver erratically. These actions were interpreted as manifesting hostile intent and both ships, after being given permission, engaged. This action, involving high speed course changes and gunfire at close range, was still in progress when Air Bus 655 took off from the joint military/civilian airfield at Bandar Abbas and headed toward Dubai. It is hard to overemphasize the fact that Bandar Abbas is also a military airfield. The Air Bus was probably not informed of the surface action taking place in the Strait. Informed or not, Flight 655 logically appeared to have a direct relationship to the ongoing surface engagement. ​(U) Even this brief and simplistic description, leads to the opinion, which the investigation drew, that Iran must share the responsibility for the tragedy. Given the fact that the surface engagement was initiated by the Iranians, I believe that the actions of Iran were the proximate cause of this accident and would argue that Iron must bear the principal responsibility for the tragedy. By any measure it was unconscionable to ignore the repeated warnings of U.S. forces concerning potential hazards of flight in the Gulf. It was especially reprehensible to allow an airliner to take off from a joint "military/civilian" airfield and fly directly into the midst of a gunfight. As for the aircraft itself, its failure not to monitor the international air distress net and not to respond to challenges was significantly negligent.
* (U) The investigation paints in vivid terms the pressure-filled environment in the VINCENNES CIC. In assessing what was reasonable performance under the circumstances it is imperative to have an emotional and intellectual feel for that picture. (U) During the critical seven minutes that Flight 655 was airborne, Captain Rogers and his CIC watch team were integrating a multitude of ongoing events. Specifically, VINCENNES was engaged in a high-speed surface battle with at least two groups of Iranian small boats--all of which had the capability to inflict serious personnel and equipment damage on VINCENNES and MONTGOMERY. Any one of these could have been a terrorist platform prepared to make a suicide run against either ship. At the same time, she was monitoring one of her helos which was airborne and had already come under attack from the Iranian small boats. CIC was also tracking an Iranian P-3 military aircraft airborne approximately 60 nautical miles to the northwest which was presenting a classic targeting profile. (i.e., furnishing information to an attack aircraft.) Captain Rogers was given and assumed tactical command of the MONTGOMERY and SIDES. He was also prepared to assume tactical command of U.S. combat aircraft ordered in and approaching the scene from outside the Persian Gulf. Additionally, VINCENNES was dealing with a fouled gun mount and maneuvering extensively to keep her remaining gun unmasked to engage the multiple target threat. At one point she was forced to make a full rudder turn at 30 knots which caused the ship to heel sharply and added to the drama. (U) In the midst of this highly charged environment, an unknown aircraft took off from a joint military/civilian airport on a flight path headed directly toward VINCENNES and MONTGOMERY. This was the same airfield from which Iran had launched F-4's in support of an attack on U.S. naval forces on 18 April and from which Iran had repeatedly launched F-14 fighter aircraft during the prior week. This unknown aircraft was 27 minutes behind any scheduled commercial airline departure from Bandar Abbas airport. Although it was flying within a known commercial air corridor, it was off the centerline some 3 or 4 miles, which was not the usual centerline profile for commercial air traffic previously monitored by VINCENNES. Moreover, its mid-range altitude was consistent with either a hostile or commercial aircraft. U (S) VINCENNES could detect no radar emanations from the contact which might identify it, but was reading a Mode III IFF squawk. This situation ​was confused somewhat when a Mode II IFF squawk was detected and the aircraft was identified as an F-14. Complicating the picture was an Iranian P-3 to the west which was in excellent position to furnish targeting information to an attacking aircraft. More importantly, the unknown contact continued at a gradually increasing speed on a course headed toward VINCENNES and MONTGOMERY. It failed to respond to repeated challenges from VINCENNES over both the military and international emergency distress frequencies. The Captain was in a genuine dilemma. On one hand the threatening contact was closing about 5-6 miles a minute. On the other, he had to act quickly to defend his ship and crew before the contact got much closer than 10 miles (in order to give himself fire depth and to stay outside of Maverick range). By the time he learned of the potential threat, his decision time was less than 5 minutes. (U) It is under these circumstances, coupled with the significant background of recent history in the Gulf, as well as the influence of current intelligence reports, that the decision of Captain Rogers to fire must be judged. Given what was in his mind at the time, there was no other prudent or responsible course.
* (U) That is not to say that everything went right. There are no "flawless" operations in combat--even when there is a successful outcome. But to say that there were mistakes made, says very little by itself. (U) Some of the information given to Captain Rogers during the engagement proved not to be accurate. Unfortunately the investigation was not able in every case to reconcile the inaccuracies. However, the more serious question to be posed here is whether these errors were significant or critical to the result. (U) The above errors aside, one is driven back to fundamentals. The villains of the piece were 6 significant problems which plagued the Commanding Officer and he could not control or discount: (U) Given the time available, the Commanding Officer could hardly meet his obligation to protect his ship and crew and also clear up all of the possible ambiguities. It is not unusual in combat to have to deal with uncertainties and conflicting information. Although it might not seem fair commanding officers do not have the luxury of reconciling all such questions before committing themselves. They have to go with the weight of evidence. These are the realities of combat and the commanding officer, if he is to function effectively, must be given some latitude to deal with them."
** (U) Shortly after liftoff Flight 655 was identified within VINCENNES as an F-14. The Identification Designation Supervisor, , had detected a Mode II squawk on his RCI and announced the contact was an F-14. The initial "unidentified assumed hostile" designation was changed to F-14. Although one officer suggested the possibility of COMAIR (commercial aircraft), no one else in the CIC took issue with the F-14 classification. The fact is the sensors gave no clear piece of information that it was not an F-14. However, if the F-14 identification had never been made, the contact would have remained designated "unidentified assumed hostile." In that event, it is unlikely that the CIC Team would have proceeded any differently or elicited additional information in the extraordinarily short time available. As long as it remained a possible "hostile," the Commanding Officer would be obligated to treat it in the same manner as he would an F-14.
** (U) At least one (possibly two) interrogation from the Remote Control Indicator registered a Mode II 1100 IFF squawk. This probably inspired the F-14 classification since the ship had intelligence that Iranian F-14's were employing Mode II code 1100. The Air Bus, however, was not squawking Mode II. When initially interrogating the target on the RCI, the IDS laid the IFF range gate on the Bandar Abbas area. Given the ducting that day, there is a possibility that the system detected the Mode II squawk of another aircraft. Because the range gate does not move with ​the hooked target automatically, in order to continue interrogating Flight 655 the range gate had to be changed manually to track with the contact. (U) Was it a critical error? No. Even if the Commanding Officer had been informed that there was no Mode II indication, that information alone has little significance. An attacker could easily be either squawking Mode II or no mode if he believes it will camouflage his identity. On 18 April, Iranian F-4s that were threatening U.S. units did not squawk any mode throughout that day. Combined with other pieces of information, a Mode II indication may help a Commanding Officer confirm or disaffirm a conclusion, but when under threat it is not definitive but only one piece in the puzzle.
** (U) The Commanding Officer did not put emphasis on the air corridor being 20 miles wide. In fact, his experience in the Gulf suggested that commercial aircraft normally tried hard to stay directly on the center line. He believed that 3 to 4 miles off the center axis was unusual and should be considered. In actual fact, however, it is again a peripheral point. An attacker would probably prefer to be in an air corridor if it confused his target. The Persian Gulf is blanketed by air corridors; they cover over 50% of the Gulf. Being in an air corridor is secondary information at best and must be combined with altitude, voice transmissions, etc., to be conclusive.
** (U) By far the most puzzling mistake to me was the ultimate misreading of altitude. The investigation established that the range and altitude information passed to the Commanding Officer was correct until the contact reached approximately 15NM. The time was 0653:45Z. Shortly thereafter, at a range between 15 and 12 miles, the Tactical Information Coordinator (TIC) reported that the altitude (which he estimated had previously reached 11,000 feet) was decreasing. At that moment, the Commanding Officer was rapidly reaching a point of no return with his Standard missiles and was inside the potential Iranian air-to-surface missile threat envelope. The TIC testified that he reported declining altitude at 11 miles, possibly 10 miles, and at nine miles. The last report was given as the missiles went off the rail and played no part in the process--the firing order had been given a few seconds earlier at 0654:05Z. Actually, the investigation concluded that the time from the first report of decreasing altitude to the decision to fire was in the neighborhood of 20 to 30 seconds. (U) The investigation was unsuccessful in satisfactorily reconciling the conclusion that the contact was descending with subsequent data analysis. The TIC's belief, however, was supported by three other watchstanders, although it is not clear that they had arrived at that conclusion independently. (U) It is impossible to say with assurance how the decreasing altitude information bore on the Commanding Officer's final decision. Obviously, whether the aircraft was ascending or descending could, when taken in the overall context, be a "significant indicator." It should be borne in mind, however, that an aircraft even at a range of 9 miles and altitude of 13,000+ feet (actual altitude at time of firing) was at sufficiently low ​altitude that it could attack VINCENNES within the next 9 miles. On the other hand, the report that the altitude was decreasing could possibly have further confirmed a developing decision to fire. The Commanding Officer testified that it was only one piece of information among many. In this reviewing officer's opinion, it is unlikely that this one piece of information would have settled the issue one way or another given the uncertainties that remained and the extremely short time left.
** VINCENNES was engaged on the surface against Iranian boats.
** The "unidentified assumed hostile" contact had taken off from a military airfield.
** The contact was heading directly at VINCENNES and its range was relentlessly closing.
** The unknown aircraft radiated no definitive electronic emissions.
** VINCENNES warnings went unanswered.
** The compression of time gave him an extremely short decision window.
** Captain Rogers had every right to suspect that the contact was related to his engagement with the IRGC boats--until proved otherwise. The proof never came.
* (U) The investigation also examined the training and watch organization of VINCENNES. Given the conditions existing on 3 July, Captain Rogers and his senior CIC watch personnel acted reasonably. That these officers relied on information from their combat team is not only reasonable--but is an absolute necessity in a pressure-packed environment. Watch teams train as a unit and function as a unit, not as separate individuals. It is impossible in the heat of battle to double check every piece of data being reported. The Commanding Officer and his senior watchstanders must rely on their subordinates. This is not to suggest that VINCENNES personnel performed perfectly in this incident; they did not. As the investigation makes clear, to say there were errors made and lessons learned is not ​necessarily to suggest culpability. (U) There were, of course, a number of areas of VINCENNES CIC performance that deserve some attention. The investigation examined the ship's training and battle organization. It went on to recommend that the AAWC position in the CIC organization be strengthened and that the "GW" not be given responsibility as a radio telephone talker. In my view, when operating in an environment that includes commercial airlines the process of "target designation" should be formalized. Also circuit discipline becomes extremely important and VINCENNES should work to improve in this area. Clearly, the GW or AAWC should confirm or disaffirm important reports (such as descending altitude)--particularly ones that change conditions just as the Captain is approaching the firing point. The Commanding Officer and the administrative chain of command should review the investigation with these points in mind with the intention of translating this tragic incident into meaningful corrective actions.
* (U) It is my view that, understanding the entire context, reasonable minds will conclude that the Commanding Officer did what his nation expected of him in the defense of his ship and crew. This regrettable accident, a by-product of the Iran-Iraq war, was not the result of culpable conduct onboard VINCENNES.
* (U)
* (U) As to the AEGIS system itself, it performed as designed and subsequent analysis indicated that the sensor data collected was accurate. This was one of our first experiences with the AEGIS under battle conditions and the Investigating Officer made a few suggestions as to refinements to be explored. (U) It should be appreciated that AEGIS was never advertised as being capable of identifying the type of aircraft being tracked. That decision is still a matter for human judgment; despite AEGIS' considerable capabilities. AEGIS' major advantages are the extended range of its sensors, its fast reaction time, the capacity to track many targets at once, its ability to send this information automatically to other units, and its data displays which combine sensor information with other inputs and better convey it to the users. Because of its long range radar it gives operators additional time to react, to gather data, and to make considered judgments. Operating close-in to a land-based airfield, however, these advantages can be severely eroded. That problem is not the ​fault of the system but geography. While the machine (in this event, AEGIS could not lengthen the Captain's decision time) cannot alter distance, there are perhaps some refinements that can make the SPY1 more effective in the close-in environment. Admiral Fogarty has recommended some improvements which I would support. I would add that a means for displaying altitude information on a contact such as "ascending" or "descending" on the LSD should likewise be examined. (U) But beyond these specific fixes, I recommend that some additional human engineering be done on the display systems of AEGIS. The objective would be to better equip it for assisting with rapid decisions in a situation such as VINCENNES confronted. Secretary Carlucci and I visited the AEGIS mock-up at Wallop's Island for a briefing on AEGIS and a partial reconstruction of the Flight 655 shootdown. It seemed to our inexperienced eyes that the Commanding Officer should have some way of separating crucial information from other data. Moreover, the vital data should be displayed in some fashion on the LSD so the Commanding Officer and his main assistants do not have to shift their attention back and forth between displays.
* (U) Although the Policy decision to utilize an AEGIS cruiser in the Strait of Hormuz and Persian Gulf was not a focus of the investigation, I believe that a few comments on that policy are in order. Probably the most serious and destructive potential threat to both military and civilian shipping in the area is the Silkworm missile. There are other serious threats, of course, but they all require overt actions on the part of a belligerent's forces in international airspace or waters and are more subject to countermeasures. A Silkworm missile, once it has been properly sited and equipped, can be launched on a few minutes notice from the belligerent's landmass. Its flight time is a matter of seconds and it possesses an imposing destructive charge. It is an awesome weapon. The most capable platform in the U.S. inventory for handling this threat is the AEGIS cruiser. It makes the greatest sense to me to utilize the best available platform against the gravest threat. Accordingly, I strongly endorse the deployment of an AEGIS cruiser to the region as long as the Iranian Silkworm missile is considered a likely threat.
* (U) I recommend the Secretary of Defense refer this investigation to the Chief of Naval Operations for follow-on actions consistent with the Investigating Officer's recommendations as modified.
* (U) Subject to the foregoing, the proceedings, findings of fact, opinions and recommendations of the Investigating Officer, as modified by the previous endorsement, are approved.
WILLIAM J. CROWE, JR. Chairman Joint Chiefs of Staff