Wikipedia indicates that the USS Vincennes misidentified Iran Air Flight 655:

Crucially, Vincennes misidentified an Iran Air Airbus A300 civilian airliner, Iran Air Flight 655, as an attacking F-14 Tomcat fighter aircraft. The Iran Air Flight 655 was climbing at the time, and her IFF transponder was on the Mode III civilian code rather than on the purely military Mode II, as recorded by Vincennes's own shipboard Aegis Combat System. Vincennes fired two radar-guided missiles and shot down the Iranian civilian airliner over Iranian airspace in the Strait of Hormuz, killing all 290 passengers and crew on board.

Based on the narrative (and any other supportable information): Does the root cause of misidentification comprise:

  • Failure to follow procedure (Military / Civilian IFF, etc.)?
  • Equipment Failure?
  • Human factors (Fatigue)?

The questions are posed because this is the first of at least two Iranian-originating civilian flights that are misidentified by military personnel: I am wondering if there is a pattern, that can produce a lesson-learned (when the final report is published).

  • 7
    $\begingroup$ You have two data points, 30 years apart, whose only obvious commonality (beyond being accidental shoot-downs) is the county they both departed from. Essentially every other potentially relevant detail differs: nationality of the shooter & of the airliner, equipment shooting and being hit, and a plethora of differing circumstances. I doubt that parallels between these two incidents will be nearly as interesting as a detailed analysis of each one individually. Although, getting truthful, accurate details from Iran right now seems, um, challenging. "Scientific impossibility," right? $\endgroup$
    – Ralph J
    Jan 11, 2020 at 16:30
  • $\begingroup$ @RalphJ There is a glimmer of hope that the data will be available: Today, the Iranian leaders have indicated that Iran owns the second data point. I would like to see the international community work together and harvest lessons-learned $\endgroup$
    – gatorback
    Jan 11, 2020 at 16:42
  • $\begingroup$ lack of research, and the mistaken belief that life in the 1980's was identical to life now. $\endgroup$ Jan 13, 2020 at 13:40

1 Answer 1


tl;dr We don't know.

The US Government has not made enough information available to answer this question. The official Iranian and US reports contradict each other. Inofficial accounts of sailors on other USN vessels operating in the vicinity at the same time contradict both the official US report as well as statements made by Vincennes commanding officer.

There are several possible explanations, many of which have not been officially acknowledged, and probably, the real cause will be a combination of multiple factors. And some of those are easy to address:

  1. User Interface Design: the target tracking system recycles target designations. Shortly before the shootdown, the system had assigned a new target designation to the aircraft and recycled the old designation for a fighter operating over 100 miles away. When the CO asked what the classification for the target designation was, the answer was "fighter" and that it was descending, which was correct for that target designation, but was actually for a completely different aircraft now.

    • Don't Do That!
  2. No access to current flight plans: the crew only had access to the standard regular schedule, but not to updated flight plans, e.g. including delays or cancellations. On the day in question, the flight was delayed by over half an hour.

    • Assets used for monitoring mixed-use airspace should be equipped with civilian radios and be in contact with ATC.
  3. Ergonomic Design: the lights were so dark, and flickered every time the weapons were fired, that the crew assigned to monitor the airspace couldn't read the printed out flight schedules.

    • Better lighting. Or, put the schedules / flight plans into the computer. Even better: integrate them into the target tracking system.
  4. Timezone confusion: the flight schedules were printed out in Iranian time, but the ship's time was Bahrain.

    • One word: UTC.
  5. Missing Equipment: the Vincennes had no possibility of using civilian frequencies (other than the international distress frequency 121.5), so they had no way of knowing that the "unresponsive" aircraft was in fact in constant communication with ATC.

    • See #2. Note that directly after the incident, the US Navy did install tunable VHF radio on all ships in the Gulf.
  6. Wrong Frequency: of the 10 attempts to establish contact with the aircraft, 7 were made on military frequencies. Obviously, being a civilian aircraft, the Airbus had no way of hearing this.

    • Train crew to remember that failure to respond to a military frequency does not imply hostile intent, especially since civilian aircraft won't even be able to respond.
  7. Speed confusion: when the Vincennes adressed the unidentified aircraft, they gave the aircraft's speed in groundspeed as 350kts, but the indicators in the aircraft would have read 300kts indicated airspeed. Since the speed was wrong, the pilots may have thought the calls were made to a different aircraft operating in the vicinity whose speed was closer to the one in the call.

    • Make it clear in your transmission that you are talking about groundspeed.
  8. A year earlier, another USN vessel was (mistakenly) hit by Iraqi missiles. Her commanding officers received official Letters of Reprimand, effectively destroying their careers, stating that defense of the ship is the first duty. This may have put the CO under additional pressure, fearing for his and his family's livelihood.

    • Don't punish people for being hesitant in highly complex combat situations involving close proximity of civilians.
  9. Scenario Fulfillment is a psychological condition affecting both individuals and groups where once a situation looks like a certain training scenario, that scenario will be followed to the end, filtering out all Information that does not fit the scenario. The US Government has put forth the possibility that the entire bridge crew may have collectively suffered from this condition.

    • Psychological training.
  10. The crew was under stress since they had illegally and unprovoked entered Iranian waters, and were simultaneously also engaged in a firefight with Iranian gunboats (which Vincennes provoked by illegally sending her helicopters into Iranian airspace). Either of these two infractions would have been cause for Iran to send fighters to intercept and attack the ship.

    • See #9.
  11. The CO was known to be a hot-headed aggressive guy looking for fights, and even creating them if there was none. He may have been looking too hard and found one where there was none.

    • Don't hire such guys, filter them out using psychological evaluations.
  • 1
    $\begingroup$ Your last paragraph is dead wrong. It would be a bit closer to correct to observe "don't promote such guys, filter them out" and "improve command training" - it took roughly 20 years to get to even be eligible to a the captain of an Aegis cruiser, to include a previous command tour on a smaller combatant. The rest of your answer is a good review of how that scenario is presented in officer training modules. You also missed the critical factor: there was no Visual Identification, and since the Cruiser was not operating with a battlegroup, no airbore aircraft to send that way to get a VID. $\endgroup$ Jan 13, 2020 at 13:43
  • $\begingroup$ On point 1, I read somewhere (got no source, though) that the radar operator had put the cursor over the plane on his screen before it left the airport, which assigned it a mixed civilian/military mode on IFF. After it took off a fighter taxied to the runway and since the cursor on the radar was still over the airport the readout changed to the military IFF squawk from it. $\endgroup$
    – TomMcW
    Jan 13, 2020 at 18:28

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