Shepherd commenced his Royal Australian Air Force service with the 1971 Royal Australian Air Force Academy intake, graduating in December 1974 with a Bachelor of Science (Physics) degree from the University of Melbourne followed by a Postgraduate Diploma in Military Aviation.
He had operational flying tours on Mirage III fighter aircraft at Royal Australian Air Force Base Butterworth in Malaysia, the F-111 strike bomber at Royal Australian Air Force Base Amberley, both as a line pilot and as the Training Flight Commander and as a flying instructor at Number 1 Flying Training School Royal Australian Air Force Base Point Cook. He has approximately 4500 flying hours, including 2500 hours in the F-111. He has held staff appointments at 82 Wing (F-111) Headquarters, as the Assistant Defence Adviser at the Australian High Commission in Singapore, and in Force Development in the field of capability analysis.
He also undertook staff training at the Joint Services Staff College.
His command appointments were Commanding Officer of Number. 6 Squadron(F-111), in the rank of wing commander, and Officer Commanding Number.
82 Wing (F-111) as a group captain. He was promoted to air commodore on 1 December 1998 and served two years as the Chief of Staff at Headquarters Air Command.
He was the Director General Operations at the Defence Signals Directorate from January 2001 until October 2002, when he moved on to become Director-General Joint Operations and Plans in Strategic Operations Division.
He was promoted to air vice marshal on 2 December 2003 and appointed Air Commander Australia taking effect 15 December 2003. On 23 May 2005, the Minister for Defence announced that, upon promotion to air marshal (as of 4 July 2005), Shepherd would succeed Angus Houston as the Chief of Air Force (CAF). On 4 July 2008 his 37-year career in the Royal Australian Air Force came to an end with his retirement.
His last official function was to be the Reviewing Officer of the Officer Training School Graduation Parade, held at Royal Australian Air Force Base East Sale, however due to unwanted weather conditions the Parade was cancelled.
He was given one final stairway guard by the young men and women of the Australian Air Force Cadets, who were on a camp at Royal Australian Air Force Base East Sale at the time. He was succeeded as CAF by Air Marshal Mark Binskin.
Shepherd is known throughout the Royal Australian Air Force for calling out "Cooee", a distinctive Australian vocalisation used mainly in the outback, with which he ended his first address as Chief of Air Force. He attended Brisbane State High School.
His interests include gardening, rugby league football, travelling and understanding other cultures.
