On June 4, 1918, at Brooks Field, Clark and a companion went out on a "pleasure accession" that Monday morning. He was an experienced pilot but that day there were alternating hot and cold air currents which caused the plane to become unstable. He then went into a tailspin due to the currents and dashed into the earth. He was knocked unconscious, fractured both limbs and had several internal injuries. On the night of June 4, 1918, the night after the crash, he passed away at 8:30. His companion regained consciousness.