EASA SIB 2013-11R1: ACAS II — Manoeuvres Based on Visual Acquisition of Traffic

What to do

Aircraft manufacturers and design organizations should review and update AFMs and AOMs to remove any contradictory information regarding visual acquisition of traffic versus RA instructions. Operators must ensure their crews are trained to respond immediately to RAs as per SERA.11014. Any incorrect manuals should be reported to EASA, and competent authorities should disseminate this SIB to inspection staff to raise awareness. No specific compliance deadlines are stated.

Summary

EASA Safety Information Bulletin 2013-11R1 is a revision of the original SIB 2013-11 and addresses the use of ACAS II (also known as TCAS II) manoeuvres based on visual acquisition of traffic. It applies to all aircraft equipped with ACAS II systems and clarifies that flight crews must respond immediately to Resolution Advisories (RAs) unless safety is compromised. The bulletin emphasizes that visual perception of traffic may be misleading and should not override RA instructions.

What changed

This revision updates the guidance to ensure that Aircraft Flight Manuals (AFMs) and Aircraft/Equipment Operating Manuals (AOMs) do not give credit to visual acquisition of traffic when it contradicts RA alerts. It reinforces compliance with Standardised European Rules of Air SERA.11014, requiring immediate response to RAs regardless of visual cues. The document also announces an upcoming update to EASA AMC 20-15 to reflect these clarifications.

Why it matters

The bulletin is critical for aviation professionals because disregarding RA instructions based on visual traffic acquisition can reduce the safety benefits of ACAS II systems. Operators, manufacturers, and maintenance organizations must ensure manuals and procedures align with regulatory requirements to maintain safe separation and avoid potential mid-air collisions. Compliance ensures consistent and correct pilot responses to collision avoidance alerts across all airspace and weather conditions.