What is the purpose of standby air data in avionics?

• A. Provide weather data.
• B. Provide navigation data.
• C. Provide cabin pressure readings.
• D. Provide redundant air data to maintain safe indications when main ADC fails.

Answer: (D)

Standby air data provides a backup path for essential air data when the primary air data system isn’t available. The air data system delivers measurements like dynamic pressure and static pressure to compute airspeed, altitude, and vertical speed. If the main air data computer or its sensors fail, the standby path uses an alternate pitot/static source and a separate processing channel to keep those critical indications alive for the standby instruments and the cockpit displays. This ensures continued safe operation and situational awareness even in the event of a sensor or processor failure. Weather data, navigation data, and cabin pressure readings come from other systems, not from standby air data, which is specifically about keeping reliable air data even during a failure of the primary ADC.