In instrument flight, what is the purpose of an instrument cross-check?

• A. To increase reliance on a single instrument.
• B. To measure fuel consumption.
• C. To continually verify attitude, altitude, and airspeed using multiple instruments to detect errors.
• D. To display engine temperature.

Answer: (C)

Instrument cross-check is the ongoing process of verifying that readings from the aircraft’s flight instruments are consistent by comparing multiple indicators. This continual verification of attitude, altitude, and airspeed across several instruments lets you detect discrepancies and catch instrument errors or failures early, which is crucial in instrument flight. For example, if the attitude indicator shows a stable level attitude while the altimeter or airspeed indicator suggests a different state, you recognize a potential error and can rely on other instruments or standby instruments instead. This practice fundamentally reduces dependence on a single instrument and keeps your situational awareness accurate. It isn’t about measuring fuel use or engine temperature.