[malcolm]

Serious enough to need a fix but operators can take up to 5 years to do so. Strange.........

DATE:10/03/10SOURCE:Air Transport Intelligence newsFAA mandates Airbus collision avoidance modification By John Croft
The US FAA has finalised an airworthiness directive (AD) that will require operators of more than 500 Airbus A320 family aircraft to update critical avionics software related to the aircraft's traffic collision avoidance system (TCAS).

The estimated costs of the upgrade, which takes four hours to complete, is roughly $15,000 per aircraft.

FAA's decision to adopt the new rule is the result of two near mid-air collisions that occurred between A320 family aircraft, incidents that prompted the European Aviation Safety Agency (EASA) to issue an airworthiness directive on the TCAS alerting function in November 2008.

Investigators concluded that human factors issues related to the incidents, which involved resolution advisories issued by TCAS, included a lack of visibility of "relevant information" on the primary flight display regarding the flight control inputs necessary to avoid a collision.

"This condition, if not corrected, could result in erroneous interpretation of TCAS resolution advisories, leading to an increased risk of mid-air collision," says the FAA. The FAA rule is identical to the original directive issued by EASA.

FAA first proposed to mandate the software upgrade in July 2009, calling for changing out the Airbus electronic instrument system software with a new version that "consists of a change in the needle colour and thickness and an increase in the width of the TCAS green band".

The rule requires operators to change out the software, per a January 2008 Airbus mandatory service bulletin, within five years.

[Don Hudson]

Malcolm;

Thanks. I believe this comes from the possibility of mis-reading the TCAS avoidance display on the PFD. I know that Air France and Lufthansa did long studies using their FDA information on TCAS responses and found incorrect responses in many events. The "fly to" green band and the "fly away from" red band could be misinterpreted on the display. We may ask how that is possible if we saw the display but the data that shows misinterpretation is there in their flight data programs.

I know a software engineer for a major US organization who designed a series of 28 different events which would trigger on an incorrect TCAS response and record all the details for trending examination so the kind of response and nature of the error could be addressed. It was a simple yet brilliant addition to an FDA Program which would have provided tracking and trending capability to target training improvements. I will leave you one guess as to who never supported it or bought into it when presented and proposed. I haven't seen the AD or the changes to the presentation; any links?

[malcolm]

Don: Here is the goto . The cost quoted by the FAA is quite different than that quoted in the news article that I posted earlier.

FAA Final Rule