Which role did Oliver Jelks play in World War I?

In 1917, soon after the United States entered the war, brothers Oliver Robinson Jelks (1893-1974) and Howard Coates Jelks (1897-1984) enlisted in the Aviation Section of the United States Army Signal Corps. The brothers received pilot's training and were stationed in France. The war ended with neither seeing active combat. Both brothers kept diaries while in training. Oliver's diary, kept from November 17, 1917, until September 1, 1918, recorded descriptions of military duties, camp conditions, and sight-seeing treks, as well as their first solo flights in May 1918.