Cath Roberts joined the Royal Australian Air Force in 1983 to study Aerospace Engineering. She graduated from No 28 Course Engineering Cadet Squadron in 1986.
AVM Roberts completed her first posting as a maintenance engineering officer supporting flight test on CT4, PC-9, DC-3, Iroquois, Squirrel, Blackhawks, Mirage, Macchi, and F111s at the Aircraft Research and Development unit. She was posted to HQSC as a logistics engineer during the introduction of the F/A-18 Classic Hornet, and was responsible for a technical program to recover the Macchi MB326 aircraft post a wing failure in flight. AVM Roberts was then posted as flightline and maintenance manager on F/A-18 Hornet aircraft at No 77 and No 481 Squadrons. After establishing the F404 Engine Recovery program, AVM Roberts posted to the UK for the Hawk Lead In Fighter project, and remained there until introduction of the Hawk into RAAF service in 2000.
After completing a Masters of Management at the Joint Command and Staff Course in 2001, she was posted to the Airworthiness Coordination and Policy Agency. In this role AVM Roberts received a Conspicuous Service Cross for her work in ADF airworthiness oversight of introduction of major aviation capabilities, establishing ADF operational airworthiness regulations and developing new airworthiness frameworks for charter and unmanned aircraft.