A corporate jet captain reported an airborne conflict with a light aircraft approaching sua.

Attributes
ACN	927602
Time
Date	201101
Local Time Of Day	0601-1200
Place
Locale Reference	SUA.Airport
State Reference	FL
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 135
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	Cruise
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine Flight Crew Rotorcraft
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 7000 Flight Crew Type 800
Events
Anomaly	Conflict Airborne Conflict
Miss Distance	Horizontal 500 Vertical 0

Narrative:

My aircraft was cleared for a visual approach to runway 30. Approach control cleared us to descend to 2500 MSL and proceed to sua. Our TCAS was clear over the airport. Conditions around the airport were VMC. We notified approach control when we had a visual on the airport per their request. They transferred control to sua tower which cleared us to land runway 30. While on the downwind to runway 30 at 2500MSL I noticed out of the corner of my eye a [light aircraft] at our same altitude passing from our 1100 to 0100 position. I rolled the aircraft to the left and started a descent passing behind the other aircraft. The aircraft came to within 500ft or so of [us]. As my aircraft was rolling out of the evasive maneuver we received an RA alert advising us to descend. We notified the tower that we were complying with an RA. They in turn told us they were just then picking up a primary contact that they were not in radio contact with. We finished the approach with a normal landing.

Original NASA ASRS Text

Title: A corporate jet Captain reported an airborne conflict with a light aircraft approaching SUA.

Narrative: My aircraft was cleared for a visual approach to Runway 30. Approach control cleared us to descend to 2500 MSL and proceed to SUA. Our TCAS was clear over the airport. Conditions around the airport were VMC. We notified approach control when we had a visual on the airport per their request. They transferred control to SUA tower which cleared us to land runway 30. While on the downwind to Runway 30 at 2500MSL I noticed out of the corner of my eye a [light aircraft] at our same altitude passing from our 1100 to 0100 position. I rolled the aircraft to the left and started a descent passing behind the other aircraft. The aircraft came to within 500ft or so of [us]. As my aircraft was rolling out of the evasive maneuver we received an RA alert advising us to descend. We notified the Tower that we were complying with an RA. They in turn told us they were just then picking up a primary contact that they were not in radio contact with. We finished the approach with a normal landing.

Data retrieved from NASA's ASRS site as of April 2012 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.