TCAS Safety Bulletin

Some very important safety information about TCAS equipment and its use is now available in the form of a Safety Bulletin. We are encouraging all operators of such equipment to download this bulletin for review.  Here is an excerpt to give you a little more information on the content of this bulletin:

RTCA SC-147 was reactivated in April 2004 and charged with developing changes to the reversal logic as well as investigating opposite responses to some TCAS resolution advisories (RAs). As a result of this work, the committee agrees that operators of TCAS II equipment should ensure that their TCAS training programs provide the proper emphasis on assuring that flight crews properly respond to initial RAs that require a reduction in vertical speed. SC-147 has prepared this bulletin to advise all operators of aircraft equipped with TCAS II/ACAS II that there have been events where the crew improperly responded to the RA announced as "Adjust Vertical Speed Adjust" (AVSA). This negative RA requires a reduction in vertical speed to either 2000, 1000, 500, or 0 feet per minute. The incorrect responses occur when the crew responds to the RA by increasing vertical speed, rather than reducing vertical speed. In other words, the crew responds in the opposite direction to the commanded RA.

To obtain a copy of the complete TCAS Safety Bulletin go to:

For more information or help obtaining a copy of this safety bulletin contact:

Nancee Pruett
Technology Development
Sr. Management Analyst
(202) 267-7575
(202) 267-5111- fax
Email: