The Results of ACAS II Operational Evaluation based on Pilot Reports in Japan
1997 Volume 1997 Issue 88 Pages 23-36
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1997 Volume 1997 Issue 88 Pages 23-36
The ACAS II operational evaluation in Japan has been conducted as part of international cooperative activities since 1990. The results have been reported at the ICAO/SICAS (SSR Improvement and Collision Avoidance Systems) panel and the working group meetings to exchange the information among countries participating in the evaluation. Since many unnecessary alerts were detected in such evaluations, ACAS II logic was improved from version 6.0 to 6.04A and its improvement was completed in Japan before the beginning of 1995. After the evaluation, the ICAO SARPs of the ACAS II were implemented on November 9, 1995, and the official operation of ACAS II in Japan started on January 4, 1996. While the SICAS panel recommended the international standards, it asks any countries to continue operational monitoring.
This paper presents the results of ACAS II operational evaluations/monitoring from January 1, 1995 to January 31, 1996. In this period, 242 RAs were reported. The proportion of the aircraft equipped with ACAS II of major airlines in Japan is 64%. The total flight hours in this period is about 389,000 hours. The proportion that pilots followed the RA is about 80%. In 65% cases, pilots thought that the RAs were necessary and available. Pilots also gave comments that the RA was consistent with ATC in roughly 50% cases. However, in about 20% cases, pilots described that the RA was inconsistent with ATC. With regard to the altitude deviation, 70% of ACAS maneuver resulted in the altitude deviation within 700ft, but in about 15% cases, the deviation exceeded 1000ft.
These results have contributed to the ICAO/SICASP for deciding its future activities.
