This is the official Turkish radar track of the Russian aircraft they shot down, in red. It briefly transited a tiny neck of Turkish land – less than two miles across where the Russian jet passed – twice. I calculate that each “incursion” over Turkish territory would have lasted about 10 seconds, assuming the plane was flying slowly at 600mph. That Turkey shot down the plane for this is madness, and absolutely indefensible. It is fairly obvious from the track that the plane was operating against Turkish sponsored Turkmen rebels inside Syria, and that is why the Turks shot it down.
But the inescapable conclusion is that the true madness would be for the UK to get involved in Syria and make a complex and volatile situation still worse, and risk being dragged into wider conflict.