Date: 201406
Local time of day: 1801-2400
Location: N90.TRACON, NY
Light: Night
Aircraft: Light Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class B N90
ATC / advisory: TRACON N90
Second aircraft: Medium Transport; Low Wing; 2 Turboprop Eng
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Workload; Distraction; Situational Awareness
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Contributing factors: Human Factors; Staffing; Airspace Structure
Primary problem: Staffing

Narrative: I was working three radar positions combined:  LOVES; VIKKY & SEALL.  Aircraft X was descending on the BUONO4 arrival route into HPN.  He had crossed GWENY intersection at 11;000 FT and was descending to 6;000 FT as instructed by me; still established on the arrival route.  Aircraft Y; was also inbound to HPN; routed HTO...KEYED...BDR...RYMES...KHPN.  He had just crossed KEYED intersection at 7;000 as instructed by the adjacent controller (position I308) and was on my frequency.  These two routes converge just north of CCC.  The normal but unofficial Standard Operating Procedure for the sector is to take the BUONO4 arrival off the route once they have begun descending out of 11;000 by turning them left direct BDR.  This saves the descending aircraft approximately 10NM of travel and keeps the arrival stream compact.  This was my plan; had I turned Aircraft X when I should have; he would have been 10NM in front of Aircraft Y.  But I got distracted by some VFR aircraft criss-crossing IFR traffic to the SW of BDR; and by a VFR who was calling for advisories but using very confusing position reporting and incorrect altitude reports.  While attempting to locate the as-yet unidentified VFR aircraft (was not sure he was even in my airspace); I neglected to turn Aircraft X towards BDR.  Aircraft X descended on a NE-bound heading on a converging course towards Aircraft Y who was established on a NW-bound heading.  When I realized the aircraft were converging; I took immediate action; turning Aircraft X left to a heading of 360.  I recognized that this was inadequate; so I turned Aircraft Y left to a 240 heading in an attempt to turn him behind Aircraft X.  As Aircraft X was already descending out of 7;000 FT as he was turning; I had no choice but to have him continue his descent; trying to stop the descent at that point would have only made the situation worse.  The speeds of the aircraft (both 250 KTS) and the trajectory made it impossible to maintain separation.  I am told the aircraft passed within 1.43 NM of each other; 400 FT separation.  I was working three positions combined; and the only other Radar Controller (SATCS) was working four positions combined.  The staffing in our sector is less than half of what it was in 1994 when our facility experienced a record number of operational errors.  The Regional Assessment Team assembled to research common contributing causes of operational errors that year reported too many combined positions being a major contributing factor.   We have been working with combined positions as the norm for so long that formal SOP procedures are all but unused; vectors and short-cuts are the 'new SOP.' I should have stopped Aircraft X at 8;000 feet; ensuring that I turned him and had separation before descending him further.  This is what I normally would have done; especially if I had been working the VIKKY position alone.  Due to the constant working of LOVES VIKKY SEALL combined; the routine of turning aircraft off the BUONO4 arrival route has become habit; over-riding common sense.




Synopsis: N90 controller reports of working a combined sectors and having an operational error due to distractions of VFR aircraft calling him.