Date: 201603
Local time of day: 0601-1200
Location: ZDC.ARTCC, VA
Flight conditions: VMC
Light: Daylight
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class E ZDC
ATC / advisory: CTAF ZZZ; Center ZDC
Second aircraft: Small Aircraft
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Training / Qualification; Communication Breakdown
Second reporter function: First Officer; Pilot Not Flying
Anomaly: ATC Issue All Types; Conflict NMAC
Detector: Automation Aircraft RA; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Contributing factors: Environment - Non Weather Related; Airspace Structure; Airport; Human Factors; Procedure
Primary problem: Human Factors

Narrative: Aircraft X was eastbound heading to the airport; which is an uncontrolled field. There was VFR traffic out in front of him that was not in communication with ATC and squawking 1200. I gave Aircraft X a discretionary descent to 3;000 feet. I also called the VFR traffic to Aircraft X. I called the traffic a second time and the pilot stated that he had the aircraft on his TCAS. I called the traffic again as he got closer to the VFR aircraft. I called the traffic one more time when he was directly over top of the VFR aircraft and only separated by about 400 feet. A few moments after that the pilot told me that he responded to an RA and to take 'evasive action.' He said that he had the airport in sight and wanted to cancel his IFR clearance. I acknowledged him and cleared him from the center frequency. I immediately told my supervisor what had happened.I recommend that the pilot stop his descent above the VFR traffic until he is safely past the aircraft. That is why I gave him a discretionary descent so he could level off at any time.


Second narrative: Visual approach; during initial descent; data was loaded into FMS for landing then pressed send and FMS went blank. 'Dead'. I was then on Comm 2 announcing our position to Unicom for uncontrolled airport procedures. Captain was on Comm 1 talking with ARTCC. Captain was told of a VFR target maneuvering in the vicinity. I did not hear the conversation since I was talking on Comm 2. I looked at the MFD and suddenly noticed a yellow target pop up within 5 miles 12 o'clock at four hundred feet low and climbing. Now less than 5 miles at 200 feet below I told the captain to stop the descent.Since he was maneuvering VFR eyes outside; at the same time we got an 'RA to descend' we were approximately 3000 feet. The captain responded until clear of conflict. We were both quite vigilant looking outside below 10;000 feet and prior discussed the possibility of VFR traffic because of the clear weather. I never saw the target neither did the Captain. Evidently the other aircraft was on ATC frequency not Unicom. As we heard ATC ask the other aircraft if they saw us; they did not.There was good vigilance on our part even discussing the possibility of high volume of VFR flyers around an uncontrolled airport. The other aircraft was doing maneuvers too close to the airport for large aircraft arrival evidently not monitoring the Unicom frequency or announcing their position. Captain followed TCAS RA instructions to descend. [Recommend] discontinuing service to uncontrolled airports especially where flight training is conducted.


Synopsis: ZDC Controller reported an aircraft inbound to an uncontrolled airport had converging VFR traffic. The Controller issued traffic advisories instead of assigning an altitude or vectors to avoid the traffic. The flight crew responded to a TCAS RA to avoid the traffic. The First Officer also reported their account of the event.