That was definitely a screw-up by Doocy, but as for the tragic mistake itself, keep this in mind what was occurring at the time the
Vincennes fired the missle.
Iran had gunboats in the water in the vincinity of the USS Vincennes and USS Montgomery.
About five minutes before IR655 took off from Bandar Abbas one of gunboats had fired at a helicopter from the Vincennes.
The cruiser had then turned to engage the gunboats and, in response, the gunboats had sped towards the Vincennes, as if to fire, according to the US military account.
Both the Vincennes and the Montgomery had then opened fire with five-inch guns, sinking two Iranian boats and damaging a third.
While still engaged with the Iranian boats, equipment onboard the Vincennes detected an approaching aircraft.
The aircraft headed directly for Vincennes on a constant bearing at high speed, approximately 450 knots, The New York Times report quoted Adm. Crowe as having said. “A warning was sent on both military and civilian distress signals beginning at 10.49 am. This procedure was repeated several times, but the aircraft neither answered nor changed its course.”
The crew on board the Vincennes noted that the aircraft was dropping in altitude and increasing its speed. At 10.51 am, it was warned again that it was approaching an American warship. Altogether, Adm. Crowe said, the plane was warned three times on the civilian distress channel and four times on the military channel.
Meanwhile, radar operators aboard the Vincennes had concluded that the inbound plane was an F-14, one of the world’s most powerful fighters at the time. About 80 of the American-built war jets had been delivered to Iran in the 1970s when the Shah’s government in Teheran (which was overthrown by the Islamic Revolution of 1979) was a US ally.
As per the US account, F-14 movements had been observed above Iran at the time, and in the prevailing highly tense situation, US commanders in the Gulf had been alerted that “Iranian units might attempt to carry out attacks against our forces over the Fourth of July holiday period”.
“The aircraft was declared hostile at 10.51 am,” Adm. Crowe said. “At 10.54 am, when the aircraft was about nine miles away, Vincennes fired two Standard surface-to-air missiles, at least one of which hit at an approximate range of six miles.”
President Reagan sent a diplomatic note to Iran that said: “This is a terrible human tragedy. Our sympathy and condolences go out to the passengers, crew, and their families. The Defense Department will conduct a full investigation. We deeply regret any loss of life.”