Avionics Systems Issues

BTeter

Tuesday, February 21, 2023 at 03:00 PM ET

Verified

Modern IMUs using MEMS are compact and far less expensive than their predecessors.

Key Takeaways:

Modern integrated cockpits generate flight-critical data (attitude, heading, airspeed, altitude) using systems like AHRS and ADCs, which often rely on "aiding" from multiple sensor inputs (e.g., GPS, air data, magnetometers) for accuracy and robustness.
Critical failures, such as blocked pitot/static lines or the loss of key aiding sensors without adequate redundancy, can lead to the loss or corruption of essential flight information, impacting primary displays and even automated systems.
In an emergency, pilots must understand their aircraft's systems, avoid fixating on a single instrument, cross-reference all available information (including standby instruments and known pitch/power settings), and be prepared to declare an emergency and seek visual conditions.

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Flight-critical information for IFR flying includes attitude, heading, airspeed, and altitude. Navigation information is high on the needs list but is not as critical as the previous items. The same is true for communications. The criticality generally follows the doctrine of aviate, navigate, and then communicate. Likewise, the FAA system safety analysis (required for equipment certifications) places the highest criticality requirements on attitude, heading, airspeed and altitude.

Here, I’ll first explain how the flight-critical data is generated in today’s digitally integrated cockpits, possible failure modes, and then I will dig into possible propagation of a failure across other functions in an integrated system. Last, I will discuss recommendations for handling the situation.