AN ACR MLG IS ISSUED AN UNCOORD CLB TO OCCUPIED ALT CLRNC.

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WHILE CLBING; WE WERE CLRED TO FL200 BY ZDC; WE WERE ADVISED OF TFC AT 10 O'CLOCK DSNDING. THEN ARTCC ADVISED 'IMMEDIATE L TURN TO 180 DEGS; DSND AND MAINTAIN FL190.' AT THAT MOMENT WE WERE CLBING THRU FL192; AND TCASII ADVISED US OF TFC AT 11:30 O'CLOCK DSNDING; 1400 FT ABOVE US; WE GOT A TA ONLY; NOT A RESOLUTION ADVISORY. WE DID AS ARTCC TOLD US; I ASKED ARTCC IF THERE WAS ANY LOSS OF SEPARATION AND HE SAID; NO. I BELIEVE THAT THERE MUST HAVE BEEN A MISCOM FROM THE PREVIOUS ARTCC AS TO THE ALT THE DSNDING ACFT WAS CLRED TO. HAD THE CTLR NOT BEEN AS ALERT AS HE WAS; I BELIEVE A LOSS OF SEPARATION WOULD HAVE OCCURRED OR POSSIBLY WORSE. I REALIZE THAT IT WOULD BE UNREALISTIC TO HAVE DSNDING AND CLBING ACFT ALWAYS SEPARATED BY MORE THAN 1000 FT VERTICALLY (AS FAR AS CLRED ALT). HOWEVER; WHEN ACFT-CLBING AND DSNDING-ARE CLEARED TO WITHIN 1000 FT VERTICALLY WHY NOT VECTOR THEM TO MORE THAN 1 MI HORIZONTAL SEPARATION SO THAT THIS DOES NOT OCCUR IN THE FUTURE. THIS WOULD ALSO HELP PREVENT NUISANCE RA'S ON TCASII DURING RAPID DSCNTS AND CLBS. NOTE: THE DSNDING ACFT LEVELED AT FL200.