We all know about why Turkey shot down a Russian airplane. Let me tell you what is going on behind the scenes. It is more than just because Russia was violating Turkey’s airspace.
The real reason is that they have conflicting interests in the Middle East. Turkey supports the rebels that want to get rid of the President Assad of Syria. Russia supports the President Assad because they are friends. Russia is bombing the rebels that Turkey is supporting. On the day of the plane being shot down, Russia was bombing near the Turkey-Syria border (probably bombing the Turkmen)
The take away from all this is that this is very complex situation. There are more than one rebel groups. Different countries are backing up the different rebel groups.
The countries involved (Turkey, Russia) have to be careful because we do not want to end up in a World War 3. Risky actions such as shooting down an airplane is not advised.