Narrative:

On radar vectors to oak airport at 7000 ft on TCASII we noticed traffic 400 ft below our altitude approximately 4 NM directly ahead of us. Shortly after, approach notified us of the VFR traffic at 6600 ft, 2 NM, 12 O'clock. PNF notified approach that we were in IMC conditions. No response from approach. TCASII called for a 1500 ft climb which we responded to. At 7400 ft, TCASII called 'clear of conflict.' upon initiating the climb, we visually saw a 737 at 8000 ft, 1 mi in front of us. About the same time, as 'clear of conflict.' PNF told approach we deviated from altitude, at 7400 ft and returning to 7000 ft, due to our TCASII alert. Another approach controller then asked us if we are in IMC conditions, which we reported affirmative. He also asked if there was any way the VFR aircraft was in VMC conditions, which we reported negative. No further incident was noted. When we received the TCASII climb, the VFR traffic was displaying 200 ft below our altitude. The 737 was also displayed on our TCASII screen, but with no verbal commands. Supplemental information from acn 271481: we had an intermittent break out of the clouds and visually sighted a boeing 737 sbound at out 10 O'clock position at 8000 ft at 2 mi. No TCASII RA was issued for this traffic. The bottoms of the cloud layer were ragged at approximately 5000 ft in the vicinity.

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Original NASA ASRS Text

Title: AN ACR MLG RPTS THAT THERE MAY HAVE BEEN AN SMA VFR IN IMC.

Narrative: ON RADAR VECTORS TO OAK ARPT AT 7000 FT ON TCASII WE NOTICED TFC 400 FT BELOW OUR ALT APPROX 4 NM DIRECTLY AHEAD OF US. SHORTLY AFTER, APCH NOTIFIED US OF THE VFR TFC AT 6600 FT, 2 NM, 12 O'CLOCK. PNF NOTIFIED APCH THAT WE WERE IN IMC CONDITIONS. NO RESPONSE FROM APCH. TCASII CALLED FOR A 1500 FT CLB WHICH WE RESPONDED TO. AT 7400 FT, TCASII CALLED 'CLR OF CONFLICT.' UPON INITIATING THE CLB, WE VISUALLY SAW A 737 AT 8000 FT, 1 MI IN FRONT OF US. ABOUT THE SAME TIME, AS 'CLR OF CONFLICT.' PNF TOLD APCH WE DEVIATED FROM ALT, AT 7400 FT AND RETURNING TO 7000 FT, DUE TO OUR TCASII ALERT. ANOTHER APCH CTLR THEN ASKED US IF WE ARE IN IMC CONDITIONS, WHICH WE RPTED AFFIRMATIVE. HE ALSO ASKED IF THERE WAS ANY WAY THE VFR ACFT WAS IN VMC CONDITIONS, WHICH WE RPTED NEGATIVE. NO FURTHER INCIDENT WAS NOTED. WHEN WE RECEIVED THE TCASII CLB, THE VFR TFC WAS DISPLAYING 200 FT BELOW OUR ALT. THE 737 WAS ALSO DISPLAYED ON OUR TCASII SCREEN, BUT WITH NO VERBAL COMMANDS. SUPPLEMENTAL INFO FROM ACN 271481: WE HAD AN INTERMITTENT BREAK OUT OF THE CLOUDS AND VISUALLY SIGHTED A BOEING 737 SBOUND AT OUT 10 O'CLOCK POS AT 8000 FT AT 2 MI. NO TCASII RA WAS ISSUED FOR THIS TFC. THE BOTTOMS OF THE CLOUD LAYER WERE RAGGED AT APPROX 5000 FT IN THE VICINITY.

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.