What is the recommended action if air data readings disagree with known ground references?

• A. Recalibrate the air data computer automatically.
• B. Cross-check with standby instruments and outside references and follow emergency procedures.
• C. Continue flight at current altitude.
• D. Ignore discrepancies.

Answer: (B)

When air data readings disagree with known ground references, treat the primary air data as unreliable and switch to the aircraft’s independent backup instruments while using outside references to verify the situation. The standby airspeed indicator and altimeter provide an independent source of information that isn’t affected by the same faults as the primary system, so cross-checking them against outside data (such as GPS altitude or known field elevation and published altimeter settings) helps you determine the real flight conditions. Follow the published abnormal or emergency procedures for unreliable air data. Automatic recalibration isn’t something you can rely on in flight, continuing at the same altitude with faulty data is unsafe, and ignoring discrepancies is not acceptable.