Narrative:

Flight progressing at 11000' nearing 30 mi out from aus, deviating around some rain showers in the area. Because we were in and out of clouds and turbulence, we asked for a descent. Descent received from aus approach to descend and maintain 5000'. We acknowledged and began descent, slowing during descent to be at 250 KTS when leaving 10000'. At approximately 10500' we were got a traffic alert on TCAS. This upgraded to a RA (resolution advisory) 'descend,' 'crossing descend,' and a command to increase vertical speed to greater than 1500 FPM. Just then observed another air carrier large transport Y coming around some clouds and appeared to be 500-1000' above our altitude and within 1/2-1 mi. This 500' sep was after increasing descent to in excess of 1500 FPM. At the time we saw the aircraft we could tell immediately that no further evasive action needed to be taken. Just then the controller attempted to issue a left turn clearance approximately 60 degrees left. The transmission was stepped on and garbled and we asked for clarification. By now being clear of conflict the controller said to disregard that heading and turned us back to previous direction. After landing called the approach facility via phone. I was told that because of WX the other aircraft was being vectored or deviating and the controller knew that sep was marginal, but stated that ' we don't always push 'em that close, but you know about the WX out there.' I asked about the aircraft altitude, but he said he didn't remember. He said, 'that's about all I can tell you--anything else you want to know?' I believe the controller realized that sep had been jeopardized but issued a turn late. Even had we turned west/O verification of clearance for us. Had it not been for TCAS I think the situation would have resulted in a near midair collision perhaps with less than 100' of altitude sep. Following the TCAS commands in this case did not cause us to deviate from our clearance since we had been cleared to 5000' and was descending anyway. I believe the WX was a factor. The WX off to the left (west) was visually and on radar significant. That is what the other aircraft was avoiding. Had we been given a left turn heading initially, we probably would have refused the clearance because of the WX.

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Original NASA ASRS Text

Title: MLG GOT A TCAS WARNING AND TOOK EVASIVE ACTION TO MISS AN LGT. APCH CTLR TURN FOR TRAFFIC INSTRUCTION WAS AFTER THE FACT.

Narrative: FLT PROGRESSING AT 11000' NEARING 30 MI OUT FROM AUS, DEVIATING AROUND SOME RAIN SHOWERS IN THE AREA. BECAUSE WE WERE IN AND OUT OF CLOUDS AND TURB, WE ASKED FOR A DSNT. DSNT RECEIVED FROM AUS APCH TO DSND AND MAINTAIN 5000'. WE ACKNOWLEDGED AND BEGAN DSNT, SLOWING DURING DSNT TO BE AT 250 KTS WHEN LEAVING 10000'. AT APPROX 10500' WE WERE GOT A TFC ALERT ON TCAS. THIS UPGRADED TO A RA (RESOLUTION ADVISORY) 'DSND,' 'XING DSND,' AND A COMMAND TO INCREASE VERT SPD TO GREATER THAN 1500 FPM. JUST THEN OBSERVED ANOTHER ACR LGT Y COMING AROUND SOME CLOUDS AND APPEARED TO BE 500-1000' ABOVE OUR ALT AND WITHIN 1/2-1 MI. THIS 500' SEP WAS AFTER INCREASING DSNT TO IN EXCESS OF 1500 FPM. AT THE TIME WE SAW THE ACFT WE COULD TELL IMMEDIATELY THAT NO FURTHER EVASIVE ACTION NEEDED TO BE TAKEN. JUST THEN THE CTLR ATTEMPTED TO ISSUE A LEFT TURN CLRNC APPROX 60 DEGS LEFT. THE XMISSION WAS STEPPED ON AND GARBLED AND WE ASKED FOR CLARIFICATION. BY NOW BEING CLR OF CONFLICT THE CTLR SAID TO DISREGARD THAT HDG AND TURNED US BACK TO PREVIOUS DIRECTION. AFTER LNDG CALLED THE APCH FAC VIA PHONE. I WAS TOLD THAT BECAUSE OF WX THE OTHER ACFT WAS BEING VECTORED OR DEVIATING AND THE CTLR KNEW THAT SEP WAS MARGINAL, BUT STATED THAT ' WE DON'T ALWAYS PUSH 'EM THAT CLOSE, BUT YOU KNOW ABOUT THE WX OUT THERE.' I ASKED ABOUT THE ACFT ALT, BUT HE SAID HE DIDN'T REMEMBER. HE SAID, 'THAT'S ABOUT ALL I CAN TELL YOU--ANYTHING ELSE YOU WANT TO KNOW?' I BELIEVE THE CTLR REALIZED THAT SEP HAD BEEN JEOPARDIZED BUT ISSUED A TURN LATE. EVEN HAD WE TURNED W/O VERIFICATION OF CLRNC FOR US. HAD IT NOT BEEN FOR TCAS I THINK THE SITUATION WOULD HAVE RESULTED IN A NMAC PERHAPS WITH LESS THAN 100' OF ALT SEP. FOLLOWING THE TCAS COMMANDS IN THIS CASE DID NOT CAUSE US TO DEVIATE FROM OUR CLRNC SINCE WE HAD BEEN CLRED TO 5000' AND WAS DSNDING ANYWAY. I BELIEVE THE WX WAS A FACTOR. THE WX OFF TO THE LEFT (W) WAS VISUALLY AND ON RADAR SIGNIFICANT. THAT IS WHAT THE OTHER ACFT WAS AVOIDING. HAD WE BEEN GIVEN A LEFT TURN HDG INITIALLY, WE PROBABLY WOULD HAVE REFUSED THE CLRNC BECAUSE OF THE WX.

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.