Narrative:

B777 was on the ILS runway 26 approach to phx, being worked by TRACON final controller. B777 was descending through 3300 ft as a southbound VFR target (traffic watch?) was merging at 2900 ft. Thankfully the B777 was not in the process of frequency change, as I observed him climbing (reaction to an RA?). This situation happens lots! With final aircraft near or below 3000 ft. A busy VFR corridor mixed with aircraft descending on final, who think they are in a sterile environment, leaves the door open to too many potentially bad sits. 1) finals controller busy and misses the traffic. 2) pilot involved in a frequency change. 3) local busy--misses traffic. 4) TCAS and conflict alert not perfect.

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Original NASA ASRS Text

Title: B-777 ON ILS APCH TO PHX RWY 26 RESPONDS TO A TCAS ALERT NEAR THE BASE OF THE PHX CLASS B AIRSPACE.

Narrative: B777 WAS ON THE ILS RWY 26 APCH TO PHX, BEING WORKED BY TRACON FINAL CTLR. B777 WAS DESCENDING THROUGH 3300 FT AS A SOUTHBOUND VFR TARGET (TFC WATCH?) WAS MERGING AT 2900 FT. THANKFULLY THE B777 WAS NOT IN THE PROCESS OF FREQ CHANGE, AS I OBSERVED HIM CLIMBING (REACTION TO AN RA?). THIS SIT HAPPENS LOTS! WITH FINAL ACFT NEAR OR BELOW 3000 FT. A BUSY VFR CORRIDOR MIXED WITH ACFT DESCENDING ON FINAL, WHO THINK THEY ARE IN A STERILE ENVIRONMENT, LEAVES THE DOOR OPEN TO TOO MANY POTENTIALLY BAD SITS. 1) FINALS CTLR BUSY AND MISSES THE TFC. 2) PLT INVOLVED IN A FREQ CHANGE. 3) LOCAL BUSY--MISSES TFC. 4) TCAS AND CONFLICT ALERT NOT PERFECT.

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.