How can you determine if the ADC has failed or its data is invalid?

To determine if the Air Data Computer (ADC) has failed or if its data is invalid, relying on the indication from the electronic instruments is crucial. When there is a failure in the ADC, electronic flight instruments will typically display error messages or anomalies that indicate the failure. These errors can manifest as flags or specific indicators that prompt the pilot for further investigation or corrective action. This direct feedback from the electronic instruments helps pilots assess the reliability of the data being presented, ensuring critical situational awareness during flight operations.

While visual indications on standby instruments could serve as a secondary check, they may not always provide the clear and immediate feedback that electronic instrument alerts do. Similarly, while audible alarms in the cockpit can indicate various faults, they may not be exclusive to ADC failures or invalid data, and a physical inspection of the ADC unit could yield information only after the failure has been suspected or diagnosed through other means. Therefore, the electronic instruments provide the most immediate and actionable data regarding the status of the ADC.