A PA24 pilot experienced an near midair collision with a high wing cessna in VFR conditions.

Attributes
ACN	718970
Time
Date	200611
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : apa.vor
State Reference	CO
Altitude	msl bound lower : 6800 msl bound upper : 8500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d01.tracon tower : bos.tower
Operator	general aviation : personal
Make Model Name	PA-24 Turbo Comanche
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Flight Plan	None
Aircraft 2
Controlling Facilities	tracon : d01.tracon
Operator	general aviation : personal
Make Model Name	Cessna Single Piston Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : cfi pilot : multi engine
Experience	flight time last 90 days : 20 flight time total : 3700 flight time type : 500
ASRS Report	718970
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	conflict : nmac
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 250 vertical : 0
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

VFR return trip from publication to apa -- visibility unlimited -- no cloud coverage. Had been using VFR flight following. Handed off from cos approach to denver approach. Approximately 20 NM sse of apa den approach advised 'radar services terminated squawk VFR contact tower (apa).' about 2 mins after flight following termination at about 7500 ft MSL aircraft appeared at same altitude from right side at 85 degree bearing near miss less than 250 ft. Aggressive evasive action left diving turn. I suspect plane transitioning underneath class B airspace from east to west. May have been maneuvering; in that this area has a lot of training flts. I cannot believe that I did not see the traffic. I cannot believe that at least one of us did not see each other.

Original NASA ASRS Text

Title: A PA24 PLT EXPERIENCED AN NMAC WITH A HIGH WING CESSNA IN VFR CONDITIONS.

Narrative: VFR RETURN TRIP FROM PUB TO APA -- VISIBILITY UNLIMITED -- NO CLOUD COVERAGE. HAD BEEN USING VFR FLT FOLLOWING. HANDED OFF FROM COS APCH TO DENVER APCH. APPROX 20 NM SSE OF APA DEN APCH ADVISED 'RADAR SVCS TERMINATED SQUAWK VFR CONTACT TWR (APA).' ABOUT 2 MINS AFTER FLT FOLLOWING TERMINATION AT ABOUT 7500 FT MSL ACFT APPEARED AT SAME ALT FROM R SIDE AT 85 DEG BEARING NEAR MISS LESS THAN 250 FT. AGGRESSIVE EVASIVE ACTION L DIVING TURN. I SUSPECT PLANE TRANSITIONING UNDERNEATH CLASS B AIRSPACE FROM E TO W. MAY HAVE BEEN MANEUVERING; IN THAT THIS AREA HAS A LOT OF TRAINING FLTS. I CANNOT BELIEVE THAT I DID NOT SEE THE TFC. I CANNOT BELIEVE THAT AT LEAST ONE OF US DID NOT SEE EACH OTHER.

Data retrieved from NASA's ASRS site as of January 2009 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.