ZBW RADAR ASSOC DESCRIBED OPERROR AT 11000 FT; CLAIMING VAGUE DEV CLRNC CONTRIBUTED TO EVENT.

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SOUTHWESTERN BOS ARRS DEVIATED S OF PVD VOR FOR WX. CAPE APCH HAD A 3 MIN DEP RESTR PLACED ON THEM 10-15 MINS PRIOR TO EVENT DUE TO TFC. THEY LAUNCHED SEVERAL ACFT AT SIMILAR TIMES; 2 OF WHICH WERE GOING TO PVD VOR CLBING TO 100 AND REQUESTING 160. 140 WAS PLACED IN DATA BLOCK BY RADAR CTLR ON 2ND ACFT. CAPE APCH CALLED AND SAID 2ND ACFT WAS DEVIATING TO S THEY WERE LOOKING FOR HIGHER. I APPROVED DEV TO S (TO KEEP OUT OF WAY OF BOS ARRS AT 110) AND CLB TO 140; AS PRE-PLANNED. 2-3 MINS LATER; 2ND ACFT HAS CLBED OUT OF 110 ON SAME HDG AS INITIAL (TOWARD PVD); THEN SLIGHTLY AND SLOWLY MAKES A WIDE TURN TO SW (ROUGHLY A 270 DEG HDG). I CALLED CAPE APCH TO GET COMS ON 2ND ACFT AND HE HAD BEEN SWITCHED TO US ALREADY. ACFT CHKED ON; RADAR CTLR TRIED TO RECTIFY SITUATION; BUT CONFLICT ALERT WENT OFF AT THAT MOMENT. THERE WAS AN ACR AT 110 DEVIATING S OF PVD FOR WX ABOUT TO MAKE AN APCH INTO BOS. BOTH ACFT WERE 4.31 MI (2ND ACFT WAS IN A RADAR RANGE GAP WHEN CONFLICT ALERT WENT OFF; BTWN QEA RADAR AND RADAR OVER PVD) AND 600 FT VERT. 1) INSTEAD OF USING DEVS USING N; W; S; AND E -- TOO VAGUE. USE MORE PRECISE PHRASEOLOGY; SUCH AS HDGS; ETC. DEVS TO THE S DEPENDING ON HOW A SECTOR IS CONFIGURED CAN BE ANYWHERE FROM 180 DEGS TO 245 DEGS ETC. (INITIATED FOR TRAINING ON RADAR ASSOCIATE SIDES.) 2) RADAR RANGE SITES -- THAT SECTOR HAS 1 RADAR RANGE SITE (3 MI RANGE) LOCATED WITHIN IT; AND ANOTHER THAT OVERLAPS IT WITH 3 DIFFERENT DEP SCENARIOS AND 3 DIFFERENT APCH/TRACONS ALL TYPICALLY HDG FOR EACH OTHER -- IT'S AN ACCIDENT WAITING TO HAPPEN.