Narrative:

Our clearance was to cross 10 mi northeast pmd at 14000 ft. We programmed the FMC for this and put it in the altitude cleared to. We remained at FL200 until our scheduled descent was indicated on the descent page. At FL195; ATC directed us to maintain FL200 and the first officer told center we had already begun our descent. Since it became apparent a conflict may exist; I started back up to FL200 whereupon he told us to expedite to 14000 ft. When I dialed a rapid descent into the vertical speed; we received an RA to climb -- eventually to climb at 4000 FPM. We told ATC immediately we had an RA and were climbing and he gave us a 40 degree left heading change 'now.' we leveled off after our conflict was clear at FL206. ZLA appreciated the maneuvering and was apologetic.

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Original NASA ASRS Text

Title: B737 AT FL200 WITH ZLA EXPERIENCED TCAS RA AFTER AN ATC DIRECTED DSCNT.

Narrative: OUR CLRNC WAS TO CROSS 10 MI NE PMD AT 14000 FT. WE PROGRAMMED THE FMC FOR THIS AND PUT IT IN THE ALT CLRED TO. WE REMAINED AT FL200 UNTIL OUR SCHEDULED DSCNT WAS INDICATED ON THE DSCNT PAGE. AT FL195; ATC DIRECTED US TO MAINTAIN FL200 AND THE FO TOLD CTR WE HAD ALREADY BEGUN OUR DSCNT. SINCE IT BECAME APPARENT A CONFLICT MAY EXIST; I STARTED BACK UP TO FL200 WHEREUPON HE TOLD US TO EXPEDITE TO 14000 FT. WHEN I DIALED A RAPID DSCNT INTO THE VERT SPD; WE RECEIVED AN RA TO CLB -- EVENTUALLY TO CLB AT 4000 FPM. WE TOLD ATC IMMEDIATELY WE HAD AN RA AND WERE CLBING AND HE GAVE US A 40 DEG L HDG CHANGE 'NOW.' WE LEVELED OFF AFTER OUR CONFLICT WAS CLR AT FL206. ZLA APPRECIATED THE MANEUVERING AND WAS APOLOGETIC.

Data retrieved from NASA's ASRS site as of January 2009 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.