Story ID: 
ACSS Introduces TCAS Change 7.1 Software Update
By: Stephen Pope
Caption: Aviation Communications & Surveillance Systems (ACSS) told AIN it is readying a software update for the Phoenix company’s TCAS II and TCAS 2000 traffic
Word Count: 167
Aviation Communications & Surveillance Systems (ACSS) told AIN it is readying a software update for the Phoenix company’s TCAS II and TCAS 2000 traffic alert and collision avoidance systems to fix two potentially serious problems in the way the technology warns pilots of traffic threats. The Change 7.1 software, due out in the fourth quarter, will add so-called “reversal logic” to the TCAS, plus a new aural alert in place of “adjust vertical speed” resolution advisories (RA). Reversal logic would allow the TCAS to amend an RA if it sees the other aircraft taking the same corrective action; for example, both aircraft climbing in response to an imminent collision. The software corrects the second problem by replacing the “adjust vertical speed” command with a “level off” RA. Aviation authorities around the world are considering whether to mandate Change 7.1 software in place of TCAS Change 7.0 software. ACSS, a joint L-3 Communications and Thales company, said it is the first TCAS maker to offer the update, which is priced at $8,500.