Flight Crew Flight Instructor; Flight Crew Commercial
Flight Crew Last 90 Days 20; Flight Crew Total 2000; Flight Crew Type 150
Communication Breakdown; Situational Awareness; Time Pressure
ATC Issue All Types; Conflict NMAC
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Human Factors; Airspace Structure
While being vectored for the RNAV XXR approach; I was instructed to descend to 6;000 feet. During the descent I got a saw a potential conflict on my ADS-B traffic display. ATC also called the traffic; but I was unable to make visual contact. The traffic was approximately 12 o'clock at 2 miles; maintaining altitude about 400 ft below us. I stopped my descent at about 6;200 feet. I still didn't have visual contact and informed ATC. The traffic began to climb directly toward us (according to the ADS-B display; which then issues a conflict alert). I took evasive action by turning right and initiating a climb.Strangely; the traffic turned in the same direction and continued to climb directly toward us. ADS-B showed 100 feet separation; directly below us. I went to a full-power climb and continued into a 360 degree turn. I informed ATC I was doing so. Thankfully the traffic broke off its turn and the conflict was resolved without incident. I never saw the traffic (and assume [they] never saw me).I resumed the approach and landed without incident. I was surprised that other than an initial traffic call; ATC provided no assistance in resolving the conflict. I believe I was in Class B airspace at the time; but did not hear the controller talking to the aircraft I was in conflict with. I'm a bit puzzled that ATC provided no assistance in the conflict resolution.From a pilot perspective; I could have taken action earlier to avoid a potential conflict. I could have asked ATC if they were talking to the other aircraft. I could have possibly looked more diligently for the other aircraft before it was in a position blocked by my own plane.The real cause was that either ATC was not talking to the conflicting aircraft (though I believe it was in class B airspace); or if a different controller than mine was; the controllers were not communicating with each other. Also; my controller didn't offer any revised vectors to avoid a conflict.
PA-28 pilot reported an NMAC that required significant evasive maneuvering.