Date: 201303
Local time of day: 0601-1200
Location: BCB.Airport, VA
Flight conditions: VMC
Weather elements / visibility: 50
Light: Daylight
Aircraft: Citationjet (C525/C526) - CJ I / II / III / IV
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class E BCB
ATC / advisory: CTAF BCB
Reporter organization: Corporate
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown
Anomaly: Aircraft Equipment Problem Less Severe; Conflict Airborne Conflict
Detector: Automation Aircraft RA; Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Procedure; Human Factors; Environment - Non Weather Related; Airport
Primary problem: Human Factors

Narrative: While conducting the RNAV approach to Runway 30 at BCB in VMC conditions and in the vicinity of ACASU fix; I maneuvered the aircraft to avoid a helicopter. We had been switched to advisory frequency but were never notified of any traffic. We had made a position report at about 15-20 miles out and had been monitoring the CTAF. No traffic was noted on the TCAS and no TA or RA was issued until after I had seen the traffic and started the evasive maneuver. The helicopter was slightly to the left of the final approach course to Runway 30. Initially I stopped my descent while I evaluated the direction and distance to the traffic. I sidestepped to the right of the approach course. I determined that the helicopter was traveling approximately in the same direction as we were; maybe slightly diverging left of the final approach course. It was not clear to me whether the helicopter was transiting the area or also approaching the airport. I asked the traffic to state his intentions on the CTAF; but there was no reply. We overtook the traffic on his right side and once clear; continued our approach and landed. At some point the helicopter did make a radio transmission that he was going to follow us to the airport and he landed a few minutes after us.I cancelled IFR on the ground with ROA Approach and the Approach Controller asked if we had encountered the traffic. He told me that shortly after he had given us the frequency change; the traffic had popped up on his screen and he had tried to call us. I told the Controller that we had maneuvered to avoid it.This was a classic case of a near collision at an uncontrolled airport in perfect VMC conditions; and underscores the importance of maintaining a visual watch when conducting an instrument approach in VMC. It is also important to not cancel IFR too early.  If we had cancelled IFR and subsequently had an accident the Controller would not have been waiting for us. I had been tempted to cancel IFR when the Controller gave us the frequency change; but had decided not to do so precisely for that reason.It is also interesting to note that during the evasive action I at some point was aware of an RA being issued by the TCAS but was so preoccupied with maintaining separation visually that I did not properly hear nor comprehend the RA.




Synopsis: A CE-525 flight crew flying the RNAV (GPS) Runway 30 approach to BCB had to maneuver to avoid a helicopter which was unknown to the TRACON prior to switching the flight to UNICOM.