[5] In 1989, he trained as a flying instructor and was thereafter posted to RAAF Base Pearce at Bullsbrook, Western Australia, serving in an instruction role at No.
After three and a half years with the squadron, he was assigned to a planning role at Headquarters Air Command in 1996, became executive officer of No.
The following year he was appointed to a capability management and development role at Headquarters Tactical Fighter Group, before assuming command of No.
In 2005, he became Director Airworthiness Coordination and Policy Agency at Australian Defence Force Headquarters.
[1][3][6] In March 2007, Turnbull deployed to Baghdad for a six-month tour as chief of staff at the Australian National Headquarters.
The citation for the award praised Turnbull's "extraordinary airmanship and exceptional managerial skill", and was made in recognition of his "exceptional service to the Australian Defence Force in air combat capability development and support to military operations".
[1][6] After two years in the role, Turnbull was succeeded as DCAF by Air Vice Marshal Stephen Meredith in July 2019 and retired from the RAAF.