Date: 201502
Local time of day: 1801-2400
Location: ZBW.ARTCC, NH
Light: Night
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Flight plan: IFR
Flight phase: Cruise
Airspace: Class G ZBW
ATC / advisory: Center ZBW
Second aircraft: Medium Large Transport
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Confusion; Situational Awareness; Distraction
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: Aircraft X was northbound; about 20 miles south of GIGTY; direct GDM VOR at 17;000 feet.  My intent was to descend him to 11;000 feet once he entered my airspace in 1 minute.  I took the handoff on Aircraft Y; who was about 20 miles west of GIGTY at 17;000 feet; eastbound towards GIGTY (I thought).  As I was about to issue Aircraft X a descent clearance; another aircraft; Aircraft Z; questioned a clearance that I had issued to him earlier.  Aircraft Z was originally told to 'Descend via the ROBUC1 Arrival; Runway 33L; resume published speed at BANKI.'  When he was about 6 miles west of Aircraft X he said that he had been given direct ROBUC by the previous controller and asked where he should resume published speed.  I immediately advised the Aircraft Z to maintain FL230; as Aircraft Z could have descended to 11;000 feet.  There is a published window of FL210-230 at GIGTY on the ROBUC STAR.  The next published altitude for an aircraft direct ROBUC is KRANN between 13;000 feet and 11;000 feet.  I was never told verbally or via automation that Aircraft Z was direct ROBUC.  So; I guess that unexpected exchange must have blown a circuit in my brain or something.  Because I completely forgot about descending Aircraft X.  That; combined with a 130 tailwind for Aircraft Y; led to the two aircraft getting close much faster than I expected them to.  I had diverted my attention to the D-Side to fix two routes on a couple of air taxis going from KBED to KISM.  While I was doing that; the Boston High controller; said to me in a loud voice; 'You have two at seventeen.'  I glanced back at the scope and immediately told Aircraft X to descend and maintain 11;000 feet; expedite.  He acknowledged and I then instructed Aircraft Y to turn 50 degrees right; expedite; and issued traffic.  Aircraft Y responded that he was climbing in response to a TCAS RA.  I said roger; but I still need you to turn right (to go behind his traffic.)  Aircraft Y refused the turn; climbed; and I believe that; combined with the expedited descent from Aircraft X; I never lost 3 miles (which we are allowed to use in that area).Links in a chain:  Number 1; I should have gotten control for descent on Aircraft X as soon as I saw the handoff coming my way on Aircraft Y.  Normally there is plenty of time to take care of it in your own airspace.  But that wind aloft was huge and Aircraft Y was converging much quicker than normal.  Normally; he would have passed behind Aircraft X by at least 3 miles.  That's why I wasn't worried.  Number 2.  Sector 19 should have left the ROBUC STAR aircraft on the procedure as required by SOP.  If they had; the Aircraft Z never would have questioned his clearance and I would not have been thrown off my rhythm. Number 3.  It would be nice; if carriers filed a preferential route.  If they had; then I wouldn't have been changing their routes. Number 4.  I've been doing this long enough that numbers 1; 2; and 3 should never be enough to cause this to happen.  I failed to ensure separation.  I got distracted when I shouldn't have.  I had 4 airplanes on my frequency; so this was inexcusable.  This is a humbling job.  Every time you feel bulletproof; the ATC gods tend to send a little message.  Message received.'




Synopsis: ZBW Controller has two aircraft in conflict and then is distracted by another aircraft asking a question. The Controller responds to the questioning aircraft and another Controller yells at that they have two at 17;000 feet. The Controller then resolves the situation by turning and descending the conflicting aircraft and does not have a loss of separation.