As an update, I did some reading on the pilot. He was Major Alexander Fomenko, a combat veteran from the civil war in the east in 2014, and after returning from that region, was based at Ozerne. At the time of the accident he was a Pilot 1st. Class, with 482 hours total flying time and proficient in all weather navigation as an instructor. He was chief of air fire and tactical combat training for the tactical aviation brigade. It's makes it likely he was on a combat training mission at the time of the crash.
It's the second Su-27 Ukraine lost within two months of each other. The previous one was during a joint exercise with NATO, with two Colonels killed, one a Ukrainian regiment commander and the other an American Colonel from the air national guard.