B737-300
Flight Crew Last 90 Days 234; Flight Crew Type 8100
Other / Unknown
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Airspace Structure; Human Factors; Weather
Vectored south of KALLA descending to 8;000 FT. Entered CB clouds at 11;000 FT. Slowing for 10;000 FT in IMC. Was advised by ATC of 'pop up' VFR traffic at our 10 o'clock. We got a TA followed by an RA immediately climbing into our position. PF started climb as directed by TCAS and slight right turn to avoid traffic. ATC gave us a 080 heading to turn in front of traffic; which we rejected as it would turn us more into RA. RA passed very close off our five o'clock and last seen 400 FT and climbing into us. Clear of conflict at 8;500 FT.
In the descent just east of KALLA going direct to HOMAL going past about 9;000 FT the TCAS started saying monitor Vertical Speed at the same time AUS Approach issued traffic; then the TCAS said climb. All this was in IMC and happened very fast. The quickest thing I could do was run the radar scale in to the five-mile scale. I started a climbing right turn because the last time I saw the echo; it was on the left side climbing. He passed just to the left on me. ATC gave me a left turn but we were already in the right turn. After the 'clear of conflict;' I looked to the left and couldn't see anything. There were broken clouds at that point. I quizzed AUS Approach and they were not talking to the aircraft. He was climbing at a high rate of climb they said.
B737 flight crew descending into AUS in IMC experiences a TCAS RA with VFR traffic not talking to Approach Control. A climb and a turn are initiated to avoid the intruder.