Narrative:

Air carrier X was established on the runway 30R ILS localizer inbound. Air carrier Y was established on the runway 30L lda localizer inbound. The pilot of air carrier X informed me (the controller) west/O being asked that he had traffic 800' above him. In fact he did have traffic 800' above, but the aircraft was established on the runway 30L lda. Nothing more was said in the air. When the pilot of air carrier X got on the ground he called and talked with my supervisor. He told my supervisor that the TCAS ii gave him traffic information and avoidance suggestions all the way down the final. If this is a reflection of the TCAS ii, and if TCAS ii is implemented system wide, safety could be greatly jeopardized. Controllers simply do not have time to reevaluate 'good control instructions/clrncs' every time a pilot becomes the least bit nervous, or 2 aircraft come within close proximity of each other (i.e., simultaneous parallel approachs). Had the pilot of air carrier X turned right, away from the traffic on the runway 30L final as the TCAS ii was telling him to do, he could have turned into the flight path of another aircraft on the downwind to runway 30R descending out of 5000'. Furthermore, I don't feel controllers can be held responsible for sep if aircraft turn/change altitude as a reaction from a TCAS ii alert.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR ON ILS WITH ANOTHER ACR ON SIMULTANEOUS PARALLEL LDA APCH GOT TCAS II ALERT AND WAS NERVOUS ABOUT TRAFFIC AND PROC.

Narrative: ACR X WAS ESTABLISHED ON THE RWY 30R ILS LOC INBND. ACR Y WAS ESTABLISHED ON THE RWY 30L LDA LOC INBND. THE PLT OF ACR X INFORMED ME (THE CTLR) W/O BEING ASKED THAT HE HAD TFC 800' ABOVE HIM. IN FACT HE DID HAVE TFC 800' ABOVE, BUT THE ACFT WAS ESTABLISHED ON THE RWY 30L LDA. NOTHING MORE WAS SAID IN THE AIR. WHEN THE PLT OF ACR X GOT ON THE GND HE CALLED AND TALKED WITH MY SUPVR. HE TOLD MY SUPVR THAT THE TCAS II GAVE HIM TFC INFO AND AVOIDANCE SUGGESTIONS ALL THE WAY DOWN THE FINAL. IF THIS IS A REFLECTION OF THE TCAS II, AND IF TCAS II IS IMPLEMENTED SYS WIDE, SAFETY COULD BE GREATLY JEOPARDIZED. CTLRS SIMPLY DO NOT HAVE TIME TO REEVALUATE 'GOOD CTL INSTRUCTIONS/CLRNCS' EVERY TIME A PLT BECOMES THE LEAST BIT NERVOUS, OR 2 ACFT COME WITHIN CLOSE PROX OF EACH OTHER (I.E., SIMULTANEOUS PARALLEL APCHS). HAD THE PLT OF ACR X TURNED RIGHT, AWAY FROM THE TFC ON THE RWY 30L FINAL AS THE TCAS II WAS TELLING HIM TO DO, HE COULD HAVE TURNED INTO THE FLT PATH OF ANOTHER ACFT ON THE DOWNWIND TO RWY 30R DSNDING OUT OF 5000'. FURTHERMORE, I DON'T FEEL CTLRS CAN BE HELD RESPONSIBLE FOR SEP IF ACFT TURN/CHANGE ALT AS A REACTION FROM A TCAS II ALERT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.