Commuter flight has near midair collision with light twin while approaching psp for landing.

Attributes
ACN	264104
Time
Date	199402
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : psp
State Reference	CA
Altitude	msl bound lower : 8000 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : psp
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 135
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	approach : visual enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Beechcraft Twin Piston Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 290 flight time total : 10000 flight time type : 5200
ASRS Report	264104
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : nmac non adherence : far other anomaly other
Independent Detector	other other : unspecified cockpit
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 500 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During our descent into psp, we were being vectored for a visual approach. As we were leveling off at 8000 ft (assigned altitude), we noticed a beechcraft baron (yellow/white) at our 11 O'clock position, opposite direction, same altitude, and approximately 500 ft away. We turned to our right and the baron turned to his right. We told the controller about the evasive action to avoid the traffic and the controller's reply was that he does not show any traffic that was in conflict with us. However, when we contacted the following controller, he concurred that by this stage, he was showing a target at our altitude and 4 mi behind us. After landing, I called the TRACON facility and supervisor by telephone, who pointed out that, due to the windmills in certain areas, radar coverage is blocked. He also indicated that the baron possibly turned his transponder on after the traffic conflict.

Original NASA ASRS Text

Title: COMMUTER FLT HAS NMAC WITH LIGHT TWIN WHILE APCHING PSP FOR LNDG.

Narrative: DURING OUR DSCNT INTO PSP, WE WERE BEING VECTORED FOR A VISUAL APCH. AS WE WERE LEVELING OFF AT 8000 FT (ASSIGNED ALT), WE NOTICED A BEECHCRAFT BARON (YELLOW/WHITE) AT OUR 11 O'CLOCK POS, OPPOSITE DIRECTION, SAME ALT, AND APPROX 500 FT AWAY. WE TURNED TO OUR R AND THE BARON TURNED TO HIS R. WE TOLD THE CTLR ABOUT THE EVASIVE ACTION TO AVOID THE TFC AND THE CTLR'S REPLY WAS THAT HE DOES NOT SHOW ANY TFC THAT WAS IN CONFLICT WITH US. HOWEVER, WHEN WE CONTACTED THE FOLLOWING CTLR, HE CONCURRED THAT BY THIS STAGE, HE WAS SHOWING A TARGET AT OUR ALT AND 4 MI BEHIND US. AFTER LNDG, I CALLED THE TRACON FACILITY AND SUPVR BY TELEPHONE, WHO POINTED OUT THAT, DUE TO THE WINDMILLS IN CERTAIN AREAS, RADAR COVERAGE IS BLOCKED. HE ALSO INDICATED THAT THE BARON POSSIBLY TURNED HIS XPONDER ON AFTER THE TFC CONFLICT.

Data retrieved from NASA's ASRS site as of July 2007 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.