I believe that.

Apart from some negligible combat missions in the early days of the revolution, it was only in the end of July 2012 that the SyAAF became actively involved in suppressing the rebellion. This was done mostly by deploying L-39ZAs on bombing runs over Aleppo and its suburbs. These sorties resulted mostly in civilian targets such as hospitals and schools being hit, and unsurprisingly led to numerous civilian casualties.

"The Syrian Arab Air Force, Beware of its Wings." By Oryx, bell¿ngcat, 1/16/17.