Iran has said the misalignment of air defence equipment was responsible for the accidental downing of a Ukrainian passenger plane in January.
In a report released on Saturday, the Civil Aviation Organisation of Iran (CAOI) blamed "human error" and poor military communication.
All 176 people on board were killed when the plane was hit by two missiles shortly after take-off in Tehran.
Iran initially denied responsibility for the incident.
But after Western intelligence officials said evidence pointed to Iranian involvement, the country admitted fault, saying it had mistaken the plane for a cruise missile. Iranian President Hassan Rouhani described it as an "unforgivable mistake".
The Ukraine International Airlines flight was downed on 8 January amid heightened tensions between Iran and America.