A TWA Martin 2-0-2 (N93211) and a Castleton Inc Douglas DC-3 (N999B) crashed following a mid-air collision near Cincinnati. All fifteen occupants on board both aircraft were killed. DC-3 N999B departed Battle Creek Airport, Michigan, at 07:33 for a VFR flight to Lexington, Kentucky. At 09:02 the TWA Martin 2-0-2 departed Cincinnati Airport runway 22. While making a right turn, the Martin collided with the DC-3 at or near the cloud base (700-900 feet). The left wing of the DC-3 came in contact with the right propeller of the Martin. The right wing of the Martin and the left wing of the DC-3 then struck resulting in disintegration of the DC-3 wing and causing such structural damage to the Martin right wing that it also separated from the aircraft. The left propeller of the Martin cut across the top of the DC-3 fuselage and through the vertical fin and rudder. Portions of the DC-3 fin and rudder separated in flight. Both aircraft crashed out of control. PROBABLE CAUSE: “Operation of the DC-3 in the control zone as unknown traffic, without clearance, very close to the base of, or in, the overcast.”