Who's Flying the New Syrian Choppers?

Weapons, in and of themselves, do not cause deaths or injury. The users of the weapons do, and in each report that has surfaced there is much hand wringing about this "escalation" and the "intractable" opposition of Russia to aiding in any way to rein in the Syrian government. A single question about these helicopters seems conspicuously absent, however. Not an answer, it must be admitted. But not even this question is being put forward.

Who exactly is flying these helicopters?