ATX X NON ADHERENCE TO ATC CLRNC DSCNT THROUGH OCCUPIED ALT HAD LTSS FROM ATX Y.

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ATX X HAD BEEN GIVEN CLRNC TO CROSS 20 SW CSN AT 7000 FT. HE WAS AT 11000 FT. ATX Y WAS TO CLB TO 10000 FT HEAD ON ABOUT 70 MI AWAY AND ASKED TO STOP AT 8000 FT. I GAVE Y 8000 FT AND FELT THE BEST ACTION NOW WAS TO TAKE X OVER Y INSTEAD OF UNDER. I RECLRED X (STILL AT 11000 FT) TO AMEND ALT; MAINTAIN 9000 FT AND TO PLAN ON XING 15 SW CSN AT 7000 FT. X READ BACK 'ROGER; OUT OF 11000 FT FOR 9000 FT (SHORT PAUSE AND STATIC) 15 SW CSN AT 7000 FT. WHEN ACFT ABOUT 10 MI APART; CALLED TFC TO X AND TOLD HIM TO EXPECT LOWER WHEN CLR. TFC Y AT 8000 FT. HE ACKNOWLEDGED. SHORTLY THEREAFTER; I SAW X AT 8400 FT AND DSNDING. I TURNED X TO 090 DEGS AND Y TO 770 DEGS. ACFT PASSED WITH ABOUT 3 MI INSTEAD OF 5 MI. SUPPLEMENTAL INFO FROM ACN 266564: ZDC CLRED ATX Y FROM 11000 FT TO 7000 FT; 20 MI SSW OF CSN VOR. WE REMAINED AT 11000 FT BECAUSE WE WERE STILL 40 MI FROM THE VOR AND IN SMOOTH AIR. ZDC THEN RECLRED US TO DSND TO 9000 FT AND CROSS 15 MI SSW OF CSN VOR AT 7000 FT. THIS WAS THE CLRNC READ BACK AND WE STARTED THE DSCNT. THE DSCNT WAS CARRIED ON THROUGH 9000 FT AS WE WERE 25 SSW OF CSN VOR. PASSING THROUGH 8000 FT IN ORDER TO MAKE THE 15 SSW AT 7000 FT XING RESTRICTION; CTR ASKED US IF WE WERE MAINTAINING 9000 FT. WE REPLIED NEGATIVE; WE WERE CLRED TO 7000 FT; 15 SSW OF CSN VOR. THE CTLR TOLD US TO MAINTAIN 8000 FT AND GAVE US A HDG OF E (090 DEGS). THE CTLR THEN CAME BACK AND SAID THE CLRNC WAS TO DSND AND MAINTAIN 9000 FT AND EXPECT 7000 FT 15 MI SSW OF CSN.