What is meant by 'degraded mode' in CSOSS terms?

• A. A state where all subsystems operate at peak performance.
• B. A state where a system is offline.
• C. A state where one or more subsystems operate at reduced capability or reliability while still enabling essential functions.
• D. A reboot state where all faults are cleared.

Answer: (C)

Degraded mode means the system stays in operation but not at full capability. When a fault or limitation affects one or more subsystems, the design allows those parts to run at reduced capability or reliability so essential functions can still be performed. For example, if a sensor or display is partially failed, the rest of the system can continue to provide critical information, though with lower performance or fewer features. This keeps mission-critical tasks going while the faulty parts are isolated or repaired.

This isn’t peak performance, nor is it completely offline. It isn’t a reboot state intended to clear faults. Degraded mode is about maintaining essential operation by operating with reduced capability.