Air Traffic Control Fully Certified
Human-Machine Interface; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict
Air Traffic Control Issued New Clearance
ATC Equipment / Nav Facility / Buildings
I stopped my one aircraft at 040 by cancelling his approach clearance. This was because the controller next to me had an aircraft that was going through his and my final and was conflicting with him. Due to a big tailwind; the trailing aircraft was given a late speed reduction and eventually was broken out to be re-sequenced. I then gave aircraft one an approach clearance once the conflict was resolved. I had the turboprop on a 330 degree heading (on base) to follow aircraft one. I then made a couple transmissions to other aircraft on frequency. I glanced down at the turboprop and the ATPA was displaying a red bat pointed at the aircraft I was re-sequencing passing off the turboprop's left. This confused me and I thought I had already turned the turboprop onto final. I realized that he was still on a 330 heading when the CA alerted me. I then took corrective action and the turboprop told me he was responding to his TCAS. A B737 was the aircraft he was responding to. The B737 was on the other final and had the turboprop in sight maintaining visual separation. I think in this situation; ATPA was a distraction more than a helpful tool. In the past I have used the 'cones' or 'bats' to show an aircraft's heading. At a glance when the ATPA showed the turboprop's proximity to the aircraft passing off his left the 'bat' pointed in a direction towards his 'turn on' heading to final.
Conflict developed between two air carriers conducting parallel approach procedures. The Automated Terminal Proximity Alerts (ATPA) tool introduced a measure of confusion contributing to the event.