FAA issued an airworthiness directive (AD) on Thursday requiring operators of the Airbus A320 family to update software in their traffic collision avoidance systems (TCAS) following two near-mid-air collisions.
The directive, effective April 15, 2010, requires U.S. operators of the estimated 564 aircraft to upgrade their Electronic Instrument System software to V60, which introduces modifications to the vertical speed indication to further improve the legibility in the case of TCAS Resolution Advisory. This modification consists of a change in the needle color and thickness and an increase in width of the TCAS green band. European regulators adopted this rule in November 2008.
"One of the Human-Machine Interface (HMI) factors was the lack of visibility of relevant information on the Primary Flight Display (PFD). This condition, if not corrected, could result in erroneous interpretation of TCAS Resolution Advisories, leading to an increased risk of mid-air collision," according to the AD.
According to the directive, FAA estimates this work will cost U.S. operators about $8.3 million, or $14,800 per aircraft.