A near midair collision occurred in the vicinity of msn airport when the reporter's lancair and a C-...

Narrative:

Under positive control by msn approach control arriving from the west and descending out of 3;500 ft for msn airport to a left base for runway 03; we heard a traffic alert given to a cessna 310 from approach control. 'Traffic at 12 o'clock; less then a mile; descending out of 3;000 ft is a lancair.' we were then advised; 'traffic at 1 to 2 o'clock; less then a mile; climbing out of 2;500 ft is a cessna 310.' I was the pilot flying from the right seat. I immediately looked right and saw a cessna 310 staring back at be from my 2 o'clock position; climbing at me; with no relative movement in either direction; only quickly getting larger. I immediately put our lancair in a climbing left turn and watched the cessna 310 pass to our rear by 300 feet; and 100 feet below. I could hear ATC's audio alert tone going off when he gave us the advisory. We were both VFR; but under positive control in class C airspace with squawk codes. It was not busy at the time. More should have been done in this situation. I believe my evasive action prevented a serious incident. The flight resumed as normal; and a normal landing was made at msn on runway 03.

Original NASA ASRS Text

Title: A NMAC occurred in the vicinity of MSN airport when the reporter's Lancair and a C-310; both VFR in MSN Class C airspace and in contact with Approach Control; received late traffic advisories from the Controller.

Narrative: Under positive control by MSN Approach Control arriving from the west and descending out of 3;500 FT for MSN airport to a left base for Runway 03; we heard a traffic alert given to a Cessna 310 from Approach Control. 'Traffic at 12 o'clock; less then a mile; descending out of 3;000 FT is a Lancair.' We were then advised; 'Traffic at 1 to 2 o'clock; less then a mile; climbing out of 2;500 FT is a Cessna 310.' I was the pilot flying from the right seat. I immediately looked right and saw a Cessna 310 staring back at be from my 2 o'clock position; climbing at me; with no relative movement in either direction; only quickly getting larger. I immediately put our Lancair in a climbing left turn and watched the Cessna 310 pass to our rear by 300 feet; and 100 feet below. I could hear ATC's audio alert tone going off when he gave us the advisory. We were both VFR; but under positive control in Class C airspace with Squawk codes. It was not busy at the time. More should have been done in this situation. I believe my evasive action prevented a serious incident. The flight resumed as normal; and a normal landing was made at MSN on Runway 03.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1030069
Time
Date	201208
Local Time Of Day	0601-1200
Place
Locale Reference	MSN.Airport
State Reference	WI
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Lancair 235
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	None
Aircraft 2
Make Model Name	Cessna 310/T310C
Person 1
Function	Pilot Flying
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 20 Flight Crew Total 2700 Flight Crew Type 5
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 300 Vertical 100

A near midair collision occurred in the vicinity of msn airport when the reporter's lancair and a C-310; both VFR in msn class C airspace and in contact with approach control; received late traffic advisories from the controller.