 Pentland completed the course at Central Flying School, Uphavon, and became an instructor there, gaining promotion to flight lieutenant before leaving the RAF on 20 July 1926 and returning to Australia.In 1927, Pentland formed Mandated Territory Airways with entrepreneur Albert Royal to fly freight to and from the goldfields of New Guinea.The pair bought a DH.60 Moth biplane, which Pentland ferried to the firm's base at Lae in February 1928.