What does the term "crosscheck" mean in IFR flying?

In IFR (Instrument Flight Rules) flying, the term "crosscheck" refers to the practice of verifying multiple instruments to ensure accuracy and consistency in the aircraft's flight data. This is a critical skill for pilots, as relying on a single instrument can lead to errors, particularly when flying in conditions where visibility is poor or when relying solely on visual references is not possible.

Crosschecking involves continuously monitoring instruments such as the altimeter, airspeed indicator, attitude indicator, and heading indicator to confirm that they provide complementary information. For example, if the altitude indicated by the altimeter seems inconsistent with the vertical speed shown on the VSI (Vertical Speed Indicator), a pilot would crosscheck these readings to identify any discrepancies. This process helps pilots maintain control of the aircraft and ensures adherence to safe flight parameters, especially in challenging conditions where precision is paramount.

The significance of crosschecking cannot be overstated, as it enhances situational awareness and reduces the risk of instrument failure or misinterpretation. This not only contributes to overall flight safety but also enables the pilot to make informed decisions during the flight.