DSTO has been working for more than a decade on the development of tools to monitor the atmospheric corrosion of military aircraft. Initially, this work involved the development and use of sensors, both corrosion and environmental. The work has evolved to include corrosion models and prognostic capabilities to give a more complete corrosion prognostic health management (CPHM) system. This paper will give a historical perspective of the development of these tools at DSTO and elsewhere along with their uses and shortcomings. It will also explain how increases in the understanding of both atmospheric and aircraft corrosion have fed into the development of a more complete CPHM system. The current system is being developed by DSTO for the Australian Defence Force (ADF) with a view to facilitating condition-based maintenance for corrosion prevention that will replace maintenance dictated by either flying hours or service duration. The system functions by using sensors to measure the environmental exposure of the aircraft and models to determine the extent of corrosion expected from this exposure. The CPHM system will give the maintenance engineer a tool that will enable condition-based maintenance to be achieved and remove the requirement for costly inspection procedures, especially of hard to access areas. Finally, the work being undertaken to extend the CPHM system will be discussed.