There were a series of events which caused the shoot down, BUT again, why didn't anyone doublecheck the information.
No time - the non-responsive Airbus was shot down literally within seconds of reaching the airspace above the warship.
The radar control officer thought that he saw the aircraft descending when infact it was ascending, this was confirmed by the warships computer loggs..
Side scan radar was not availabe which would have given more accurate height data.
Oh,and WX radar is not something an enemy attacker radiates - another way to differientiate civ from military - had the Iran Air flight had the unit on (SOP ?), surely would have had a different outcome.