"In the 1990′s I worked for Hughes Aircraft of Canada developing large scale air traffic control systems for international customers around the world. Air traffic control systems are large, complex, mission critical systems. After extensive requirements gathering and analysis an overall architecture for the air traffic control system was defined including complete hardware and software requirements. Development of something so large required the overall architecture to be broken down into subsystem components which were then distributed to different teams for development. The lead systems engineering team had the responsibility of integrating developed subsystems into the final air traffic control system and ensuring that the overall architecture design and requirements were met."