In January 1917, after spending Christmas on leave in London, he commenced pilot training at Netheravon, flying solo after 55 minutes of dual instruction. On 24 February 1917, he returned to serve a second tour on Corps Co-operation machines as a pilot flying B.E.2s and R.E.8s with 15 Squadron. On 25 March, Barker claimed another scout "driven down". On 25 April 1917 during the Arras Offensive, Barker, flying an R.E.8 with observer Lt. Goodfellow, spotted over 1,000 German troops sheltering in support trenches. The duo directed artillery fire into the positions, thereby avoiding a counter-attack.