EASA SIB 2023-10: Aircraft Flight Manual Operational Procedures for Air Data Loss or Erroneous Air Data

What to do

Design and change approval holders should review and, if necessary, update Aircraft Flight Manuals or supplements to include detailed procedures for air data loss or erroneous data scenarios. They should ensure pilots are guided on selecting correct air data sources when multiple probes exist and on actions to take if all sources are unreliable, including reporting to ATC and managing transponder settings. Coordination with EASA and use of DOA privileges is recommended for implementing these updates. No specific compliance deadline is stated.

Summary

EASA Safety Information Bulletin 2023-10 is an informational document addressing operational procedures in Aircraft Flight Manuals for handling air data loss or erroneous air data. It applies specifically to Supplemental Type Certificate holders of CS-23 category aircraft. The bulletin highlights the risk of erroneous altitude data being transmitted to Air Traffic Control and collision avoidance systems, potentially compromising vertical separation safety.

What changed

This bulletin introduces recommendations for design and change approval holders to ensure Aircraft Flight Manuals include comprehensive procedures for Continued Safe Flight and Landing in the event of air data loss or erroneous air data. It emphasizes the need for clear guidance on selecting correct air data sources, managing multiple probe configurations, and preventing transmission of erroneous data to ATC and ACAS. The document does not mandate changes but encourages updates to operational procedures accordingly.

Why it matters

The bulletin is important for aviation professionals because erroneous air data can lead to incorrect altitude information being communicated to ATC and onboard collision avoidance systems, increasing the risk of loss of vertical separation. Operators and maintenance teams must ensure that flight manuals provide pilots with clear instructions to manage air data failures safely. Compliance teams should be aware that while this is not currently an airworthiness directive, addressing these procedures proactively enhances flight safety and regulatory alignment.