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The initial design of the Orbiter flight control system was limited to the quad-redundant computer complex. Systems management and nonavionic functions were contained in a fifth computer, which was not considered flight critical. This concept was well into development when a blue ribbon panel was asked to review all aspects of the Approach and Landing Test (ALT) phase of the Space Shuttle Program to verify that the design was proper. One of the conclusions reached by the panel was that an unnecessary risk was being taken by not providing a backup flight control system for the first flight. This decision was based on the relative complexity of the computer synchronization scheme being implemented and the lack of a direct manual flight control capability