ACR X DSCNT TO OCCUPIED ALT IN HOLDING PATTERN HAD LTSS FROM Y. SYS ERROR.

Narrative

I WAS WORKING THE KENTON SECTOR (R53) AT ZDC. THIS IS A PRIMARY ARR/DEP SECTOR FOR PHL/DCA/BWI/ADW/NSF/ACY. I WAS HOLDING ARR TFC AT TERRI INTXN ON THE DPNT3 ARR AT 10000 FT 11000 FT; 12000 FT MSL. I HAD A SBOUND PHL DEP AT 10000 FT SBOUND OVER OOD TO SBY. I ALSO WAS CTLING AN 11000 FT MSL EBOUND JFK ARR JUST S OF THE TERRI PATTERN ON V44 TO JOIN V229 ACY. THE ADJACENT SECTOR R51 (CASINO) WAS HOLDING TFC AT VCN FOR PHL AT 8000 FT; 11000 FT; AND 12000 FT. THE DQO (18) SECTOR HANDED ME OFF AN ACY ARR; X; RTED DQO V29 ENO SIE ACY AT 11000 FT. THE USUAL ALT IS 13000 FT. (FIRST STEP IN A BROKEN CHAIN.) I WAS FORCED TO VECTOR THE ACY ARR AROUND THE 11000 FT TFC AT TERRI AND VCN HOLDING PATTERNS AND KEEP X N OF JFK 11000 FT TFC. THE RSI CTLR AND I (SECTORS SIT SIDE-BY-SIDE) WERE DISCUSSING THE ARR AS X IS IN R51 AIRSPACE. I VECTORED THE ACY ACFT X AROUND AND TO FOLLOW 11000 FT TFC IN BOTH HOLDING PATTERNS. I TOLD THE R51 CTLR I WAS GOING DIRECT ACY WITH THIS ARR AND HE CONCURRED WHEN TFC WAS CLR. I DID NOT REALIZE THE R51 CTLR HAD TURNED COM OF THE VCN HOLDERS TO PHL APCH. THE R51 CTLR ADVISED ME THAT THE 11000 FT TFC WAS CLR AND I COULD BEGIN DSCNT OF THE AC7 ARR X. I ISSUED THE TURN AND DSCNT AND THEN OBSERVED THE 12000 FT TFC Y BEGIN TO DSND! THE CTLR AT PHL HAD BEGUN DSCNT OF THE ONLY TFC WHICH WAS A POSSIBLE PROB. THE R51 CTLR AND I USED DIFFERENT TECHNIQUES TO HOLD TFC. HAD I KNOWN THE VCN 12000 FT TFC WAS ON PHL; I WOULD HAVE ENSURED THEY KNEW ABOUT MY ARR. I ASSUMED BOTH I AND R51 USED THE SAME TECHNIQUE OF TURNING OVER ONLY THE LOWEST HOLDING TFC IN THE PATTERNS. HE DIDN'T. SUPPLEMENTAL INFO FROM ACN 264486: AS ACFT AT 11000 FT OVER VCN BEGAN TO DSND; THE R53 CTLR VECTORED HIS ARR IN BEHIND HIM. I CALLED PHL2 TO MAKE A POINTOUT; HOWEVER PHL8 WAS STARTING THE ACFT AT 12000 FT DOWN. THEY HAD TO IMMEDIATELY CLB THEIR ACFT BACK TO 12000 FT. THE R53 CTLR WAS THEN ABLE TO DSND HIS ACFT INTO ACY. SEPARATION WAS LOST IN THE HOLDING PATTERN.