Air Traffic Control: the IBM 9020
Summary
The article provides a detailed history of IBM's 9020 system used for civil ATC NAS Stage A, highlighting its multisystem architecture, control program, and autonomous fault-handling (OEAP). It situates the 9020 within the evolution of automated air traffic control and draws practical lessons on reliability, real-time processing, and system diagnosability for modern distributed systems and safety-critical IT.