Which statement best describes instrument cross-checking practice?

• A. Relying on a single instrument for attitude information.
• B. Using multiple instruments to verify attitude, altitude, and airspeed.
• C. Skipping cross-check during calm weather.
• D. Substituting the magnetic compass for heading information.

Answer: (B)

Instrument cross-checking is the ongoing practice of reading and comparing information from more than one primary flight instrument to verify critical data—attitude, altitude, and airspeed—and to catch any discrepancies that indicate a malfunction. By continuously comparing the attitude indicator with the altimeter and the airspeed indicator, you confirm that your pitch/roll, altitude, and speed readings are all consistent with your control inputs and flight conditions. If readings don’t align, you know there’s either an instrument fault or a blockage in the pitot-static system, and you can follow appropriate backup procedures.

Relying on a single instrument defeats this safety check, because it leaves you blind to potential failures. Cross-checking is needed in all conditions, not just in bad weather; instruments can fail at any time, so continuous verification is essential. Substituting the magnetic compass for heading information isn’t appropriate either, since the compass has limitations and should be used in conjunction with the heading indicator and other instruments rather than as a sole source.