Narrative:

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.

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Original NASA ASRS Text

Title: B737-700 flight crew reported an NMAC on descent into BWI when an aircraft passed directly below them with 200 feet of vertical clearance.

Narrative: 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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.