This paper begins with a discussion of a cognitive engineering model, the operator function model (OFM), to guide design of artifacts for human interaction with complex systems. Such artifacts include operator aids, associates, and tutors. The paper presents an overview of the current implementation and evolution of the operator function model (OFM) and OFMspert, its computational implementation. It describes how OFMspert has been extended to support the design of two intelligent tutoring systems (ITS) for operational control of safety-critical systems. Proof-of-concept demonstrations and evaluation teaching MD-11 transition pilots vertical navigation and a case-based tutor teaching currently certified MD-11 pilots new procedures, adapted since their certification training.