Narrative:

I was the pilot monitoring with the first officer the pilot flying. We noticed a target on our TCAS 500 feet below us and a couple of miles off to the right of our course. The cloud layer was scattered to broken at our altitude; and we were in and out of IMC. At this point we were given a vector off the arrival to a heading of 050 and a descent to 2;100 feet; which was in the direction of the traffic. At the same time; we received a resolution advisory telling us to adjust vertical track. Immediately the TCAS now showed the target now above us; and the RA dictated us to adjust vs. At that point we saw the GA aircraft. The aircraft was supposed to be maintaining VFR. The aircraft passed above us; clearing us by what could not have been more than more than 300-400 feet. I believe the first officer's response to the RA was appropriate to the directions on his pfd; although his initial response might have been slightly delayed. This delay was momentary and I instructed him to 'follow the guidance' or something to that effect. The event only lasted a couple of seconds.

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Original NASA ASRS Text

Title: ERJ170 Captain reported responding to an RA while being vectored for an approach in marginal weather conditions. Crew reported passing below a GA aircraft by about 400 feet.

Narrative: I was the pilot monitoring with the First Officer the pilot flying. We noticed a target on our TCAS 500 feet below us and a couple of miles off to the right of our course. The cloud layer was scattered to broken at our altitude; and we were in and out of IMC. At this point we were given a vector off the arrival to a heading of 050 and a descent to 2;100 feet; which was in the direction of the traffic. At the same time; we received a resolution advisory telling us to adjust vertical track. Immediately the TCAS now showed the target now above us; and the RA dictated us to adjust VS. At that point we saw the GA aircraft. The aircraft was supposed to be maintaining VFR. The aircraft passed above us; clearing us by what could not have been more than more than 300-400 feet. I believe the First Officer's response to the RA was appropriate to the directions on his PFD; although his initial response might have been slightly delayed. This delay was momentary and I instructed him to 'follow the guidance' or something to that effect. The event only lasted a couple of seconds.

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.