As advanced crew support technologies will be available more and more in future military aircraft, it is necessary to have a good understanding of the possibilities in this area, taking into account operational demands and technical possibilities. A Crew Assistant (CA) is a decision support system for air crew, designed to improve mission effectiveness and redistribute crew workload in such a way that the crew can concentrate on its prime tasks. Designing a complex system with multiple crew assistants can be tackled by using a multi-agent system design. In this paper we will propose a multi-agent system architecture for crew assistants.