Flight Crew Air Transport Pilot (ATP)
Situational Awareness
ATC Issue All Types; Conflict NMAC; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Flight Crew Took Evasive Action
Human Factors; Procedure
On the RAVNN 6 Arrival into BWI; we were given a 'descend via' clearance. Passing 12;000 feet; the Controller told us to level off at 12;00 feet 'if able.' I responded that we were passing 12;000 feet right then and asked if we needed to climb back up to 12;000 feet. The Controller said; 'Disregard.' I queried the Controller to determine if we were still cleared to descend via the arrival; and he instructed us to descend and maintain 10;000 feet. Descending through approximately 10;500 feet; the Controller instructed us to turn 10 degrees left for traffic; which we did. Through about 10;300 feet; we received a TCAS RA 'don't descend.' We immediately disengaged the autopilot and leveled off at approximately 10;200 feet; and noticed on the Navigation Display that the conflicting traffic went directly under us at 10;000 feet.Had we not responded immediately and correctly to the RA; I firmly believe we would have collided with the traffic. I notified ATC that we were responding to the RA; and the Controller gave us instructions to proceed direct RAVNN and descend to 6;000 feet when able; with no further comment on; nor discussion of; the near mid-air collision or the RA. I heard one of our Company aircraft on the radio tell ATC that they also received a TCAS RA; which leads me to believe that they may have been our conflicting traffic. I think; as the flight crew; we handled the event very well. We had excellent communication and coordination; and the First Officer immediately applied corrective action to our flight path to avoid a collision. I think the Controller must have been task saturated due to the traffic volume; and perhaps lacked experience or knowledge to avoid this event. We continued the arrival and approach into BWI and landed without further incident.
[Report narrative contained no additional information.]
B737-700 flight crew reported an NMAC on descent into BWI when an aircraft passed directly below them with 200 feet of vertical clearance.