Terribus, a good summary.
In the Vincennes incident, there also seems to have been confusion on the part of the Iranian crew, who may have thought that the messages were aimed at another aircraft. In a war zone, there is little time for procrastination.

The missile launch system for the Buk missiles has been described as too complicated for a force such as the Separatists. The system was invented by the Russians in the 1970s, and would be familiar to many soldiers trained for it in the last 30 years.