On July 3 in summer of 1988, the USS Vincennes, a U.S. Navy warship, shot down an Iranian airplane (Iran Air flight 655 -- an Airbus A300 civilian airliner) over the Persian Gulf with a surface to air missile. The ship was in an Iranian water and the incident took place in Iranian airspace. Iran Air flight 655 was on its everyday flight path from Tehran to Dubai in United Arab Emirate. With 290 people dead, it is the eighth deadliest aviation disaster.
After the incident, at the Pentagon Press conference, Admiral William Crowe, chairman of the Joint Chief of Staff, said that civilian airliner was flying at 9,000 feet and descending at a high speed of 450 knots, heading directly at the USS Vincennes. However, seven weeks after the incident, on August 19, 1988, the Pentagon issued its own 63-page report on the incident which was written by Rear Admiral William Fogarty of the U.S. Central Command which refuted all the statements made by Admiral William Crowe.
Crowe said that the plane was flying outside the commercial air route but Fogarty's report stated it was flying within the established commercial air route. Crowe had mentioned that the airplane was descending whereas it was ascending.
In "Iran - Iraq war in the air 1980 - 1988" Tom Cooper and Farzad Bishop discuss the Iranian and Iraqi air forces and in the final chapter (chapter 12, pp. 276-277) they cover shooting down of Iran Air plane by USS Vincennes. There are other sources that have reported the incident. For example, History.com.
Mr. George H.W. Bush, the Vice President of the U.S. at the time, boasted the incident during a presidential campaign in 1988 by saying: I will never apologize for the United State, I do not care what the facts are."
The captain of the USS Vincennes was given a medal for the time period (April 1987 to May 1989) of service that included his role in the shooting down the civilian Iranian airplane.
Shooting down an Iranian passenger plane was the start of sanctions against Iranian civilian airplanes which have caused death of over 2000 Iranians and non-Iranians due to lack of access to airplane parts, for example (See Chicago Convention).
Many people might not know about flight 655 incident, but this incident is known among many Iranians. Every year around this time, flowers are spread where plane went down in the Persian Gulf.