Narrative:

I am only filing this to highlight a flaw in the 'stars' (standard terminal automation replacement system) collision alert feature. When aircraft appear likely to merge at conflicting altitudes; the stars system produces a 'collision alert' for both aircraft. In this specific incident; the system's response to the two aircraft that merged happened way too late. Watch the playback from this incident and notice that by [the] time the collision alert happened; it was already too late for any controller to do anything to prevent the two aircraft from merging any closer. The aircraft were going too fast and there was not enough distance for either to get out of the others way. The stars collision alert feature also produces false collision alerts at times where two aircraft will not merge; so there's an obvious flaw in this feature. In this case; this apparent flaw could have yielded grave consequences. Once again; I urge whoever reads this to study whether or not the collision alert feature here at sct is satisfactory. In my opinion; it's either too sensitive; or in this case not sensitive enough. So I guess it needs re-calibration. Please check the collision alert feature here at sct.

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Original NASA ASRS Text

Title: SoCal TRACON Controller reported a problem with the STARS Collision Alert System.

Narrative: I am only filing this to highlight a flaw in the 'STARS' (Standard Terminal Automation Replacement System) collision alert feature. When aircraft appear likely to merge at conflicting altitudes; the STARS system produces a 'collision alert' for both aircraft. In this specific incident; the system's response to the two aircraft that merged happened way too late. Watch the playback from this incident and notice that by [the] time the collision alert happened; it was already too late for any controller to do anything to prevent the two aircraft from merging any closer. The aircraft were going too fast and there was not enough distance for either to get out of the others way. The STARS collision alert feature also produces false collision alerts at times where two aircraft will not merge; so there's an obvious flaw in this feature. In this case; this apparent flaw could have yielded grave consequences. Once again; I urge whoever reads this to study whether or not the collision alert feature here at SCT is satisfactory. In my opinion; it's either too sensitive; or in this case not sensitive enough. So I guess it needs re-calibration. Please check the collision alert feature here at SCT.

Data retrieved from NASA's ASRS site 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.