In fault tree analysis, which event is typically a top-level failure mode indicating a total subsystem loss?

In fault tree analysis, which event is typically a top-level failure mode indicating a total subsystem loss?

• A. Power supply failure.
• B. Processor failure.
• C. Sensor data arrival on time.
• D. Firmware patch applied.

Answer: (B)

In fault tree analysis, the top-level event represents the total loss of the subsystem’s functionality—the complete failure you want to prevent. The processor failure is the best fit because the processor is the central element that executes the control logic and drives the subsystem’s essential tasks. When the processor stops working, the subsystem can no longer perform its core functions, leading to a full outage of that subsystem’s operation. A power supply failure could cause problems, but many systems include redundancy or multiple rails, so a single failure is not guaranteed to produce total loss. Sensor data arriving on time describes normal operation rather than a failure state. A firmware patch applied is a maintenance action, not a failure mechanism.

In fault tree analysis, the top-level event represents the total loss of the subsystem’s functionality—the complete failure you want to prevent. The processor failure is the best fit because the processor is the central element that executes the control logic and drives the subsystem’s essential tasks. When the processor stops working, the subsystem can no longer perform its core functions, leading to a full outage of that subsystem’s operation.

A power supply failure could cause problems, but many systems include redundancy or multiple rails, so a single failure is not guaranteed to produce total loss. Sensor data arriving on time describes normal operation rather than a failure state. A firmware patch applied is a maintenance action, not a failure mechanism.