Air carrier flight crew reported NMAC with another air carrier aircraft during initial approach. Flight crew stated the Approach Controller did not advise them in advance of the traffic conflict.
Synopsis
Air carrier flight crew reported NMAC with another air carrier aircraft during initial approach. Flight crew stated the Approach Controller did not advise them in advance of the traffic conflict.
Narrative
On arrival into ZZZ the Approach Controller vectored us off the arrival and gave us an intercept heading for the Runway XXR localizer kept us at 6;000 ft. which felt too high. We were then slowed by ATC from 230kts to 210kts then to 190kts. As we got closer to the localizer I mentioned to the CA (Captain) that the controller was keeping us high; we gave the controller a short time before requesting lower and were given 4;000 ft.; then shortly after reading it back we were given 3;000 ft.; the controller seemed a bit confused. throughout the descent I configured for the slow speed and descent by putting flaps out and lowering the landing gear (flaps 5 and gear down) at this point we were flying through the localizer and the CA questioned the controller; we were now at about 5;000 ft. and descending to 3;000 ft.; we received a traffic alert and told the controller and then received an RA; I immediately disengaged the A/T (autothrottles) and A/P (autopilot) and followed RA commands for a descent and was then given an immediate heading of 250 from ATC (this instruction from ATC came from a different voice on the same frequency; seemingly a different controller or a supervisor who stepped in). Then I watched as the traffic passed overhead and slightly in front; I would estimate they passed by within 500 ft. After the aircraft passed left to right the controller called out the traffic to us which was obviously much too late. Also; once the traffic passed by we received the 'clear of conflict' from the TCAS system and from here ATC gave us a turn and we're cleared for the visual to Runway XXR and the rest of the flight was uneventful. The approach controller seemed to be behind and possibly not seeing the full picture. We noticed this initially when we were left at 6;000 ft. while approaching the localizer with no descent clearance. We prompted approach who then gave us lower; 4;000 ft.; immediately after repeating the altitude the controller gave us 3;000 ft.; this was odd and seemed like they finally realized how high they had left us. The supervising approach controller should have step in and taken over much earlier to avoid this situation.
Second reporter narrative
On arrival into ZZZ the Approach Controller vectored us off the arrival and kept us at 6;000 ft. which felt too high. We were then slowed by ATC from 230kts to 210kts then to 190kts. As we got closer to the localizer I mentioned to the CA (Captain) that the controller was keeping us high; we gave the Controller a short time before requesting lower and were given 4;000 ft.; then shortly after reading it back we were given 3;000 ft.; the Controller seemed a bit confused. Throughout the descent I configured for the slow speed and descent by putting flaps out and lowering the landing gear (flaps 5 and gear down) at this point we were flying through the localizer and the CA questioned the controller; we were now at about 5;000 ft. and descending to 3;000 ft.; we received a traffic alert and told the controller and then received an RA; I immediately disengaged the A/T (autothrottles) and A/P (autopilot) and followed RA commands for a descent and was then given an immediate heading of 250 from ATC (this instruction from ATC came from a different voice on the same frequency; seemingly a different controller or a supervisor who stepped in). Then I watched as the traffic passed overhead and slightly in front; I would estimate they passed by within 500 ft. After the traffic passed left to right the controller called out the traffic to us which was obviously much too late. After seeing the traffic pass by we received the 'clear of conflict' from the TCAS system and from here ATC gave us a turn and we're cleared for the visual to Runway XXR and the rest of the flight was uneventful.[Suggest] retraining or termination of ZZZ Approach Controller. They were the direct cause of this incident; that had it not been for the quick reaction of both flight crew would have resulted in a midair collision.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.