Sail Plane
Flight Crew Private
Flight Crew Last 90 Days 35; Flight Crew Total 2800; Flight Crew Type 2000
Situational Awareness
Conflict Airborne Conflict
General None Reported / Taken
Airspace Structure; Procedure
I was flying my glider in the 'drop' area where we tow gliders and a C-17 flew right through the area at my altitude less than a mile from me.  Fortunately I saw it earlier before it turned to cross through the area.  The area the C-17 came through is a known high glider traffic area (glider symbol on sectional chart) where gliders are towed to begin flights.  There were several of us in the air when this happened and at least one glider was closer than I was.  Since this happened; C-17 traffic has repeated the same route right through this area; most recently last week when we had over 30 gliders flying.  It is not a safe practice for the [military] to run low level C-17 missions right through a known high VFR traffic area.
Glider pilot reported an airborne conflict; and questioned the practice of C-17 aircraft flying through the glider release area east of EPH at 4;000 feet.