According to the U.S. government, Vincennes mistakenly identified the airliner as an attacking military fighter and misidentified its flight profile as being similar to that of an F-14A Tomcat during an attack run; however, the ship's Aegis Combat System recorded the plane's flight plan as climbing (not descending as in an attack run) at the time of the incident.[21] The flight had originated at Bandar Abbas, which served as both a base for Iranian F-14 operations and as a hub for commercial civilian flights.[11] According to the same reports, Vincennes unsuccessfully tried to contact the approaching aircraft, seven times on the military emergency frequency and three times on the civilian emergency frequency, but never on air traffic control frequencies. This civilian aircraft was not equipped to pick up military frequencies and the messages on the civilian emergency channel could have been directed at any aircraft. More confusion arose as the hailed speed was the ground speed, while the pilot's instruments displayed airspeed, a 50-knot (93 km/h) difference.[25]
Only after the attack did the Vincennes' crew realize that the plane was a civilian airliner.
This version was finalized in a report by Admiral William Fogarty, entitled Formal Investigation into the Circumstances Surrounding the Downing of Iran Air Flight 655 on 3 July 1988 (the "Fogarty report") [6] Only parts of this report have been released (part I in 1988 and part II in 1993).
The Fogarty report stated, "The data from USS Vincennes tapes, information from USS Sides and reliable intelligence information, corroborate the fact that [Iran Air Flight 655] was on a normal commercial air flight plan profile, in the assigned airway, squawking Mode III 6760, on a continuous ascent in altitude from take-off at Bandar Abbas to shoot-down".