Medium Large Transport
Distraction; Situational Awareness; Communication Breakdown; Confusion
ATC Issue All Types; Conflict Airborne Conflict
Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Human Factors; ATC Equipment / Nav Facility / Buildings; Aircraft; Procedure
In this event; I was the pilot monitoring (PM) and the captain was the poilot flying (PF).  We were at 4000 feet on a 270 heading for radar vectors for the ILS 18L into CLT.  The approach controllers were very busy and utilizing 18L; 18C; and 18R for landing.  On the heading of 270 we were given a heading 200 to join the LOC.  As the controller issued this heading and assignment I the PM spotted traffic at about the 10:30 position level or near level at our altitude. It was a Aircraft Y.  When I spotted him; he was in a climbing left turn.  This would put him in a position to head straight for us. I immediately told the captain who was about to initiate the turn.  He had a different airplane in sight below us crossing left to right at about 3000ft.  This traffic was a brown multi-engine aircraft and was not a factor.  The PF did not have Aircraft Y in sight.  I the PM never lost sight of Aircraft Y.  As the clearance for the 200 heading to join was issued; I told the controller about our traffic level at our altitude.  The controller's response was 'Stop asking questions and just turn!'  This baffled me as this was going to be a turn directly into traffic. As the response was stated from the controller; Aircraft Y saw us.  Aircraft Y immediately made a hard left descending turn.  The maneuver that he made got him below us quickly and it seemed like he joined the LOC with us just below us and to the right side of our aircraft.  I kept him in sight until he was not a factor for us.  While all this was going on the PF delayed the turn to the 200 heading for a short time. This short time was not long enough to cause any other occurrence or instance.  We joined the LOC at a normal rate of turn and did not blow through the LOC course. Aircraft Y was never on the TCAS. We are responsible for see and avoid and that is exactly what we were trying to do as the controller just wanted us to turn not to delay his sequence.  Also the captain made a small turn when the clearance was given but when I told him of traffic he immediately stopped the turn until I said the traffic was not a factor for us anymore.
Pilot reports of a close call with another aircraft.  The other aircraft is not displayed on the TCAS; and possibly not on the Controller's radar system; because the Controller never issued traffic.