DC8 FLT CREW CLBING WITH ZBW EXPERIENCED TCASII RA WITH ENRTE ACFT AT 16000 FT AFTER ACCEPTING VISUAL SEPARATION RESPONSIBILITY.

Narrative

THE SIT INVOLVED A RELATIVELY 'CLOSE' ENCOUNTER OR 'NMAC' BTWN 2 JET ACFT JUST S OF PVD; RI; FROM WHERE THE DC8 HAD TAKEN OFF. THE GULFSTREAM WAS APPARENTLY ESTABLISHED IN CRUISE AT 16000 FT WHILE THE DC8 WAS CLBING AT 2000 FPM. THE CLB WAS TO PASS THROUGH 16000 FT. FEW XMISSIONS WERE HEARD OVER THE ASSIGNED FREQ; BUT THE CTLR ASKED THE DC8 TO MAINTAIN VISUAL SEPARATION DURING THE CLB. THE GULFSTREAM WAS FIRST SIGHTED ON TCASII; THEN FOUND SOME 10+ MI AT 9 O'CLOCK POS. WE CONTINUED CLB AT 2000 FPM AS THE CTLR ASKED US TO; BUT THE CAPT RELUCTANTLY RESPONDED 'WE WILL MAINTAIN VISUAL IF WE ARE PARALLEL.' HAVING INADEQUATE KNOWLEDGE OF THE OTHER ACFT'S INTENTIONS (PREVIOUS CLRNCS); ONGOING POS (3-DIMENSIONALLY); IT WAS DIFFICULT AT BEST TO PREVENT A NEAR MISS AND CONTINUE CLB; AS WAS REALIZED AT THE RA (OF THE TCASII) TO WHICH WE INITIATED A MANEUVER TO AVOID TFC. NOTE: THE CAPT ACKNOWLEDGES THAT WE SHOULD NOT HAVE ACCEPTED (EVEN WITH STATED LIMITATIONS) THE REQUEST; BUT WHY ASK 2 JET ACFT AT SUCH HIGH VELOCITY TO ATTEMPT SUCH A THING? IT IS DIFFICULT ENOUGH IN AN ESTABLISHED; COORD TFC PATTERN.