This is Sanke Card Nr 507, depicting thirty-victory-ace and PLM-winner Karl Emil Schäfer (1891-1917). Schäfer began the war as a member of Jäger-Bataillon Nr 10. He transferred to the air service and received his pilot training. He served in other squadrons, then he was personally chosen by Manfred von Richthofen for his Jasta 11 in February 1917. While a member of Jasta 11, he was awarded the PLM. In April 1917, he was transferred to Jasta 28 as its C.O. He was killed in combat during June 1917. Interestingly, he is remembered to this date as one of the primary members of the legendary Jasta 11.
This pose shows him in his uniform, complete with schirmütze. He had as yet to be awarded the PLM. The postcard was not mailed.