B737-800
Air Traffic Control Fully Certified
Situational Awareness; Confusion; Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors
I was training an advanced trainee on the final position. We were getting busy and our feeder controllers were giving a somewhat aggressive feed including leaving aircraft on a new arrival. When this happened; my trainee started to try and sort out some problems with the feed he was getting; forgot to turn Aircraft Y to final off the base leg. I did not realize that Aircraft Y didn't get the turn to final; resulting in a loss of separation between him and Aircraft X on the straight in to a parallel runway. I would recommend people think before leaving aircraft on this new arrival during busy sessions.
On downwind and preparing for vectors to ILS; at 4;000 feet. Solid overcast; but clear at our altitude and above. We received a heading of 070; but no altitude change. As we proceeded on the base leg; we were assigned a 130 heading. Again; no altitude change was given. This is not the norm; as we usually get a lower altitude and a clearance to join the localizer. We proceeded as assigned. As we approached the localizer course we were going to query ATC re: joining the LOC; but we were then told to look for traffic at our 2 o'clock; same altitude (I don't remember the distance given); I thought this strange as any 2 o'clock traffic would have had to been turned inside of us. No traffic was spotted; so I scanned across the horizon; where I spotted Aircraft Y at our 10 o'clock position on a converging path to our course. At nearly this same time; ATC told us to turn back to 070. I simultaneously realized that our paths were dangerously close and that evasive action was warranted. The autopilot and auto throttles were disconnected; the aircraft was banked hard to the left; throttles retarded; and a decent was initiated. Within seconds; a new Controller issued 'traffic alert; turn right (I don't recall the heading as I knew a right turn would have turned us into the other aircraft; so the instructions were disregarded.) The TCAS issued an RA to descend within 2 seconds of the ATC traffic alert. The descent had already been initiated before the TCAS RA was issued. A 'bank angle' warning was issued from the aircraft; and I leveled the aircraft out (both pitch and roll) once collision avoidance was assured. We leveled out at 3;400 feet; but I do not recall the heading. The new Controller issued a heading of 090 and 3;000 feet. We complied with this; rebuilt the automation; and continued with vectors for landing. To my knowledge; no injuries occurred. This event appears to be caused by poor ATC vectors and altitude assignments and lack of situational awareness on the part of ATC. I am unaware what Aircraft Y was assigned or if they were in compliance; but it appears they were where they were told to be; as were we. Next; we were told to look for traffic in the wrong sector. This delayed our acquisition of conflicting traffic. Finally; when the traffic alert was issued; the give vector would have turned us into the other aircraft; rather than away.
TRACON Controller providing training failed to note that the trainee did not issue a turn on vector; resulting in a conflict with parallel traffic; a new arrival procedure was cited as contributing to the error.