Narrative:

Downwind at 6000 ft and 4 mi abeam of bna, the controller asked if airport was in sight. Copilot said 'yes.' we both had field at that time. Controller cleared us to 3000 ft with expedited descent to expect base in 3-4 mi. Speed brakes were used to expedite descent, at 3000 we were cleared for visual to runway 02R and the first officer immediately replied that the airport was no longer in sight. Controller asked if traffic at 11 O'clock was in sight? First officer said 'yes,' and we saw a turbojet ahead that was no problem to avoid. Controller had given us a hard right turn to intercept ILS to runway 02R to keep clear of traffic while descending to 2200 ft. About this time, we got a TCASII resolution warning. An airlines commuter turboprop was sighted to the left and about 200 ft below our altitude heading directly beneath our aircraft on a visual. I shallowed out the bank to keep the aircraft in sight until he passed beneath us and asked the first officer to let me know when he picked the aircraft up visually so I could continue the turn without blindly turning directly over the aircraft at 200 ft. The first officer got a visual and the controller realized we could not do the ILS and gave headings 350 degrees to 3000 ft for 'another visual' when we requested a moment when he had time for a conference on WX conditions and visibility. We requested an ILS as visibility was less than ATIS reported at least 50 mins earlier. Airport was not visible on right runway. Factor: turboprop was unknown traffic until TCASII RA, then became visible through clouds. Supplemental information from acn 247764: we could not see the field and required a vector to final approach. They assigned heading 350 degrees and said expect square turn to final. While on 350 degree heading, they called out traffic to our left and ahead. We saw 2 aircraft, 1 at left 11 O'clock and approximately 3 mi, another at left 9-10 O'clock, less than 2 NM. When approach issued us a turn to final, the captain began the turn but was unable to comply with a steep turn without losing sight of the 9-10 O'clock traffic which was just below our altitude and converging. We reported ceiling visibility not acceptable and they gave us an ILS. WX on final much worse than 7 mi visibility and 1700 scattered. When we reported unable to see field and requested vector turn to final, approach kept us on 350 degree heading too long for us to maintain visual separation with parallel traffic to 02L when the right turn to final was issued. ATC had called out only 1 aircraft to us, but we saw and were reacting to what we thought was a second, uncalled traffic conflict since we saw 2 aircraft and the one that was not a factor to us was at the called out O'clock position by ATC. Perhaps we should not have originally accepted a visual approach but based on ATIS and our eyes, we thought we had plenty of visibility for it.

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Original NASA ASRS Text

Title: NMAC.

Narrative: DOWNWIND AT 6000 FT AND 4 MI ABEAM OF BNA, THE CTLR ASKED IF ARPT WAS IN SIGHT. COPLT SAID 'YES.' WE BOTH HAD FIELD AT THAT TIME. CTLR CLRED US TO 3000 FT WITH EXPEDITED DSCNT TO EXPECT BASE IN 3-4 MI. SPD BRAKES WERE USED TO EXPEDITE DSCNT, AT 3000 WE WERE CLRED FOR VISUAL TO RWY 02R AND THE FO IMMEDIATELY REPLIED THAT THE ARPT WAS NO LONGER IN SIGHT. CTLR ASKED IF TFC AT 11 O'CLOCK WAS IN SIGHT? FO SAID 'YES,' AND WE SAW A TURBOJET AHEAD THAT WAS NO PROB TO AVOID. CTLR HAD GIVEN US A HARD R TURN TO INTERCEPT ILS TO RWY 02R TO KEEP CLR OF TFC WHILE DSNDING TO 2200 FT. ABOUT THIS TIME, WE GOT A TCASII RESOLUTION WARNING. AN AIRLINES COMMUTER TURBOPROP WAS SIGHTED TO THE L AND ABOUT 200 FT BELOW OUR ALT HDG DIRECTLY BENEATH OUR ACFT ON A VISUAL. I SHALLOWED OUT THE BANK TO KEEP THE ACFT IN SIGHT UNTIL HE PASSED BENEATH US AND ASKED THE FO TO LET ME KNOW WHEN HE PICKED THE ACFT UP VISUALLY SO I COULD CONTINUE THE TURN WITHOUT BLINDLY TURNING DIRECTLY OVER THE ACFT AT 200 FT. THE FO GOT A VISUAL AND THE CTLR REALIZED WE COULD NOT DO THE ILS AND GAVE HDGS 350 DEGS TO 3000 FT FOR 'ANOTHER VISUAL' WHEN WE REQUESTED A MOMENT WHEN HE HAD TIME FOR A CONFERENCE ON WX CONDITIONS AND VISIBILITY. WE REQUESTED AN ILS AS VISIBILITY WAS LESS THAN ATIS RPTED AT LEAST 50 MINS EARLIER. ARPT WAS NOT VISIBLE ON R RWY. FACTOR: TURBOPROP WAS UNKNOWN TFC UNTIL TCASII RA, THEN BECAME VISIBLE THROUGH CLOUDS. SUPPLEMENTAL INFO FROM ACN 247764: WE COULD NOT SEE THE FIELD AND REQUIRED A VECTOR TO FINAL APCH. THEY ASSIGNED HDG 350 DEGS AND SAID EXPECT SQUARE TURN TO FINAL. WHILE ON 350 DEG HDG, THEY CALLED OUT TFC TO OUR L AND AHEAD. WE SAW 2 ACFT, 1 AT L 11 O'CLOCK AND APPROX 3 MI, ANOTHER AT L 9-10 O'CLOCK, LESS THAN 2 NM. WHEN APCH ISSUED US A TURN TO FINAL, THE CAPT BEGAN THE TURN BUT WAS UNABLE TO COMPLY WITH A STEEP TURN WITHOUT LOSING SIGHT OF THE 9-10 O'CLOCK TFC WHICH WAS JUST BELOW OUR ALT AND CONVERGING. WE RPTED CEILING VISIBILITY NOT ACCEPTABLE AND THEY GAVE US AN ILS. WX ON FINAL MUCH WORSE THAN 7 MI VISIBILITY AND 1700 SCATTERED. WHEN WE RPTED UNABLE TO SEE FIELD AND REQUESTED VECTOR TURN TO FINAL, APCH KEPT US ON 350 DEG HDG TOO LONG FOR US TO MAINTAIN VISUAL SEPARATION WITH PARALLEL TFC TO 02L WHEN THE R TURN TO FINAL WAS ISSUED. ATC HAD CALLED OUT ONLY 1 ACFT TO US, BUT WE SAW AND WERE REACTING TO WHAT WE THOUGHT WAS A SECOND, UNCALLED TFC CONFLICT SINCE WE SAW 2 ACFT AND THE ONE THAT WAS NOT A FACTOR TO US WAS AT THE CALLED OUT O'CLOCK POS BY ATC. PERHAPS WE SHOULD NOT HAVE ORIGINALLY ACCEPTED A VISUAL APCH BUT BASED ON ATIS AND OUR EYES, WE THOUGHT WE HAD PLENTY OF VISIBILITY FOR IT.

Data retrieved from NASA's ASRS site as of July 2007 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.