When the primary ADC fails, how do pilots maintain safe airspeed and performance indications?

When the primary ADC fails, how do pilots maintain safe airspeed and performance indications?

• A. They rely on GPS-derived air data.
• B. They use the autopilot to command airspeed without data.
• C. They switch to standby air data or alternate sources per procedures to maintain safe airspeed and performance indications.
• D. They ignore the ADC failure and continue as normal.

Answer: (C)

When the primary ADC fails, pilots rely on backup air data to keep essential indications accurate and meaningful. The aircraft has a standby air data system or alternate sources that are independent from the primary ADC. By selecting these backup sources per the procedures, the crew gets reliable readings of airspeed, altitude, and vertical speed, which are crucial for maintaining a safe airspeed and proper performance. This approach preserves the ability to manage speed, climb/descent, and planning for safe flight despite the failure. GPS-derived air data can’t replace the real-time air data measurements needed for speed and altitude, so it isn’t used as a substitute. Relying on the autopilot to command airspeed without reliable data is unsafe, since it would be based on faulty or missing information. Ignoring the failure and continuing as normal would also be dangerous because the flight displays and protections depend on accurate air data.

When the primary ADC fails, pilots rely on backup air data to keep essential indications accurate and meaningful. The aircraft has a standby air data system or alternate sources that are independent from the primary ADC. By selecting these backup sources per the procedures, the crew gets reliable readings of airspeed, altitude, and vertical speed, which are crucial for maintaining a safe airspeed and proper performance. This approach preserves the ability to manage speed, climb/descent, and planning for safe flight despite the failure.

GPS-derived air data can’t replace the real-time air data measurements needed for speed and altitude, so it isn’t used as a substitute. Relying on the autopilot to command airspeed without reliable data is unsafe, since it would be based on faulty or missing information. Ignoring the failure and continuing as normal would also be dangerous because the flight displays and protections depend on accurate air data.