Narrative:

There was a high volume entertainment event nearby. There were multiple light aircraft in area with multiple business jet traffic arriving IFR to an uncontrolled airport. The weather was ceiling and visibility unrestricted. I was monitoring CTAF/unicom upon terminal arrival; informed crew of the runway in use. We continued to monitor and transmit on CTAF throughout the approach and landing. In light of the unusual amount of activity around the airport; the crew planned to remain IFR as long as practical and fly the RNAV GPS approach. Approach initiated vectors for the downwind (east of airport) to get us established for the approach.approach asked if we could accept vectors to intercept the final approach course. We were cleared for the approach; and issued descent from 4;000 to 3;000 feet. Once established the aircraft can descend to the published altitude of 2;500 feet. As we were intercepting the course and beginning the descent; we received a traffic alert. We were unable to visually acquire the threat; but noted a target approaching from the left and slightly low on our TCAS display. I elected to gently arrest the descent and climb; and slightly away from the threat aircrafts' assumed path. At this point we noted a beech baron crossing the final approach path of RNAV/GPS inside of the initial approach fix; at an estimated altitude of between 3;000 and 3;500 feet heading to the east/southeast. We were not informed of another IFR aircraft flying another approach to the field that would cross our path or lead to a conflict; nor did we hear any transmissions of aircraft requesting a practice approach; or a transmission of an aircraft at our relative position on CTAF.within minutes after the event; we heard the aircraft transmit on CTAF that they would be flying a straight in approach to an intersecting runway. We can only assume that the pilot of that aircraft was completely unaware of multiple arriving IFR aircraft to our runway; and that our aircraft was flying the RNAV/GPS approach; and that they had crossed our approach corridor at a position and altitude that could cause a conflict. We assume the aircraft was on a VFR flight plan; and was perhaps visually flying using some form of guidance. Perhaps setting up for a left base to final and not monitoring or receiving traffic advisories from approach. Our aircraft landed without any further conflicts.

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Original NASA ASRS Text

Title: Lear 55 Captain on approach to an non-towered airport reported an NMAC with a unidentified VFR aircraft.

Narrative: There was a high volume entertainment event nearby. There were multiple light aircraft in area with multiple business jet traffic arriving IFR to an uncontrolled airport. The weather was Ceiling and Visibility Unrestricted. I was monitoring CTAF/UNICOM upon terminal arrival; informed crew of the runway in use. We continued to monitor and transmit on CTAF throughout the approach and landing. In light of the unusual amount of activity around the airport; the crew planned to remain IFR as long as practical and fly the RNAV GPS approach. Approach initiated vectors for the downwind (east of airport) to get us established for the approach.Approach asked if we could accept vectors to intercept the final approach course. We were cleared for the approach; and issued descent from 4;000 to 3;000 feet. Once established the aircraft can descend to the published altitude of 2;500 feet. As we were intercepting the course and beginning the descent; we received a traffic alert. We were unable to visually acquire the threat; but noted a target approaching from the left and slightly low on our TCAS display. I elected to gently arrest the descent and climb; and slightly away from the threat aircrafts' assumed path. At this point we noted a Beech Baron crossing the final approach path of RNAV/GPS inside of the initial Approach Fix; at an estimated altitude of between 3;000 and 3;500 feet heading to the east/southeast. We were not informed of another IFR aircraft flying another approach to the field that would cross our path or lead to a conflict; nor did we hear any transmissions of aircraft requesting a practice approach; or a transmission of an aircraft at our relative position on CTAF.Within minutes after the event; we heard the aircraft transmit on CTAF that they would be flying a straight in approach to an intersecting runway. We can only assume that the pilot of that aircraft was completely unaware of multiple arriving IFR aircraft to our runway; and that our aircraft was flying the RNAV/GPS approach; and that they had crossed our approach corridor at a position and altitude that could cause a conflict. We assume the aircraft was on a VFR flight plan; and was perhaps visually flying using some form of guidance. Perhaps setting up for a left base to final and not monitoring or receiving traffic advisories from Approach. Our aircraft landed without any further conflicts.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.