If ADS data is unreliable, what is the best reference for flight control?

• A. Autopilot continued on current mode
• B. Standby instruments as primary reference and use alternate data sources as needed
• C. Arithmetic cross-check with ATC data
• D. Rely on cabin announcements

Answer: (B)

When ADS data is unreliable, standby instruments provide the primary reference for flight control. These instruments are fed by independent sensors and power sources, so they remain accurate even if the main air data system is faulty. Relying on standby instruments gives you a trustworthy attitude, altitude, and airspeed reading to maintain control, while you can use alternate data sources to confirm readings or augment information as you troubleshoot. Using autopilot to stay in its current mode isn’t ideal in this situation because it may rely on the faulty data path and could maintain an incorrect flight path. Relying on ATC data or cabin announcements isn’t suitable for real-time flight control since they’re not precise or timely enough to guide hands-on control.