The signs point to this being an ambush attack on aircraft flying a routine route, IMHO.
An audio recording has emerged purporting to be the recording of Turkey warning the Russian plane.
The voice is heard saying in English: âUnknown air traffic position onto Humeymim 020, redirect to 26 miles. This is Turkish Air Force speaking - en guard. You are approaching Turkish airspace. Change your heading south immediately."
Earlier today, the surviving pilot claimed that he had not received any visual or radio warning from Turkey - contradicting Turkey's claim that they warned them numerous times.
The recording was passed on to TV news channel Al-Arabiya by a civilian pilot for Lebanese airline MEA in the sky at the time.
He claimed that this event had happened multiple times in the last week, with each warning met with silence from Russia. This clam is not verified.
This reinforces something that came to my mind:
From a civilian aircraft in the area:
"He claimed that this event had happened multiple times in the last week, with each warning met with silence from Russia."
The warning may have become so routine that they were no longer considered relevant. And 17 seconds spent crossing a finger of ridges protruding into Syria doesn't seem like it would be worth starting WWIII over by shooting down a Russian Jet.
Just my 2 cents.