RADAR ASSOCIATE CTLR AT ZBW DESCRIBES OPERROR AT FL230 LIKELY CAUSED BY READBACK ERROR DURING WX RE-RTE PROCS.

Narrative

BWI; DCA; IAD ROUTED OVER HNK; PSB DUE TO WX. ALT AND MI IN-TRAIL DUE TO ZNY (FL220 AND 25 MI). ALL HEAD ON TO NORMAL FLOW OF DNY SECTOR 24. ACFT #1 EBOUND VECTOR AT FL230. ACFT #2 (WX RE-RTE); WBOUND VECTOR CLBING TO FL220 HEAD ON WITH ACFT #1. ACFT #2 WAS INITIALLY CLRED TO FL230. CTLR ISSUED NEW ALT OF FL220 ABOUT 25 MI AWAY FROM ACFT #1. TFC WAS PASSED AS WELL. ACFT #2 NEVER ACKNOWLEDGED THE NEW ALT OF FL220. ACFT #1 AND ACFT #2 LOST MINIMUM SEPARATION ABOUT 35 MI SW OF ALB. BOTH ACFT WERE TURNED TO AVOID COLLISION. ACFT #1 REACTED TO TCASII AND CLBED TO FL237. SUPPLEMENTAL INFO FROM ACN 626520: FL220 WAS ISSUED TO ACFT Y TO GO UNDER ACFT X. ACFT Y DID NOT TAKE THE CLRNC. SUPPLEMENTAL INFO FROM ACN 626732: WE RECEIVED A TA FROM TCASII FOR AN ACFT ABOVE US AT 1 O'CLOCK POS; DSNDING. NEXT WE RECEIVED AN RA TO DSND; WHICH WE DID. THE TCASII WORKED PERFECTLY; JUST AS ADVERTISED. RA GUIDANCE KEPT US CLR OF TFC IN IFR CONDITIONS. THE TA GAVE US EXCELLENT SITUATIONAL AWARENESS AND WE WERE READY FOR THE EVENTUAL RESOLUTION GUIDANCE.