Project Selection

During the planning stages, USA invited a variety of projects to participate in the CMMI case study. To gain the most benefit from applying CMMI, the use of a systems-level project was preferred. However, existing work commitments precluded their involvement during the case study time period.

Two projects were selected. Members of both software project teams were familiar and comfortable with process discussions, models, and assessments. This allowed for a quick startup of the case study. The CMMI case study participants were from the Flight Software Program Element:

• Primary Avionics Software System (PASS)

• Cockpit Avionics Upgrade (CAU)

The legacy PASS project was selected because the core processes in place for this case study were the same as the core processes in place at the time of the SW-CMM case study. Participation of this project provided continuity in case studies from the SW-CMM book to this book and is an example of a high-maturity project implementing CMMI practices.

The CAU project was selected because it is a new project in its process definition phase and can easily implement CMMI practices. This project also has customer and USA management visibility and therefore must have sound processes in place.

Primary Avionics Software System Project Background

The Space Shuttle's flight software is responsible for the guidance, navigation, and flight control functions performed during all phases of shuttle flight. Flight software consists of more than 400,000 lines of code that run on the shuttle's onboard computers. USA also develops and maintains more than one million lines of application tools code that supports configuration management, software builds, test, simulation, automatic verification, and software reconfiguration.

The USA software development efforts include requirements analysis, design, development, testing, certification, and maintenance of the avionics software for the data processing system of the Space Shuttle Orbiter. Responsibilities include development of the flight, test, and support software; integration of software furnished by NASA; and design, analysis, and test support to NASA.

The unique requirements for flight software, such as redundancy management, fail-safe operations, complex timing, and synchronization, had to be developed to produce human-rated, error-free flight software for shuttle space flight.

Cockpit Avionics Upgrade Project Background

The Cockpit Avionics Upgrade (CAU) project is a major hardware and software development project responsible for the design, development, verification, and delivery of hardware and software for four orbiters, an initial lay-in of spares, and ground avionics facilities. With the goal of first flight in 2006, the CAU project aims to enhance the cockpit to include many state-of-the-art features available in other avionics systems.

The CAU represents a third generation of avionics for the orbiters and builds on the Multifunction Electronic Display System, or "glass cockpit," already installed onboard Atlantis and Columbia. CAU Command and Display Processors will replace the Multifunction Electronic Display System integrated display processors. With these new devices, a much greater variety of displays and more data filtering and analysis will be possible.

The CAU project includes two significantly new software applications. The first of these applications will continuously determine which launch abort option is most attractive based on the current state of the vehicle. The second new application will reduce crew workload by providing more sophisticated vehicle health monitoring functions and by limiting the number of alarms that sound for nonemergencies.