Close proximity GA-small aircraft GA-small aircraft. Reporter on IFR flight plan working sna on V23.

Attributes
ACN	87404
Time
Date	198805
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : sli
State Reference	CA
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Route In Use	enroute airway : v23
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 15 flight time total : 800
ASRS Report	87404
Person 2
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : nmac non adherence : published procedure other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact none taken : insufficient time
Consequence	Other
Miss Distance	horizontal : 0 vertical : 10
Supplementary
Primary Problem	Flight Crew Human Performance
Situations
ATC Facility	other physical facility

Narrative:

I was cruising on an IFR flight plan on V-23, heading 120 (near damps int), altitude 5000, talking with coast approach. Another plane (single engine, low wing) passed 10' underneath me. He came from my 7 O'clock position and left in my 1 O'clock position about 20-30 knots faster than me. He was not seen as a transponder or primary target on the coast approach radar (according to controller). He was in level flight for as long as I could see him (about 3 minutes) after the near miss. My main purpose in making this report (I also filed a near miss report) is to point out that radar coverage along the orange county coast from balboa intersection to ocn VOR is not very good. The other aircraft in this near miss was large enough and 'metal enough' to return a descent radar echo. Yet none was seen. His altitude was such that he could have been a danger to commercial traffic departing sna or military arrivals to MCAS el toro. Many times, at altitudes from 3-5000', coast approach has been unable to see my aircraft, even when squawking an assigned transponder code in this particular, heavily traveled area. Something should be done to improve radar coverage in this area before a serious accident occurs.

Original NASA ASRS Text

Title: CLOSE PROX GA-SMA GA-SMA. REPORTER ON IFR FLT PLAN WORKING SNA ON V23.

Narrative: I WAS CRUISING ON AN IFR FLT PLAN ON V-23, HDG 120 (NEAR DAMPS INT), ALT 5000, TALKING WITH COAST APCH. ANOTHER PLANE (SINGLE ENGINE, LOW WING) PASSED 10' UNDERNEATH ME. HE CAME FROM MY 7 O'CLOCK POSITION AND LEFT IN MY 1 O'CLOCK POSITION ABOUT 20-30 KNOTS FASTER THAN ME. HE WAS NOT SEEN AS A TRANSPONDER OR PRIMARY TARGET ON THE COAST APCH RADAR (ACCORDING TO CTLR). HE WAS IN LEVEL FLT FOR AS LONG AS I COULD SEE HIM (ABOUT 3 MINUTES) AFTER THE NEAR MISS. MY MAIN PURPOSE IN MAKING THIS REPORT (I ALSO FILED A NEAR MISS REPORT) IS TO POINT OUT THAT RADAR COVERAGE ALONG THE ORANGE COUNTY COAST FROM BALBOA INTERSECTION TO OCN VOR IS NOT VERY GOOD. THE OTHER ACFT IN THIS NEAR MISS WAS LARGE ENOUGH AND 'METAL ENOUGH' TO RETURN A DSCNT RADAR ECHO. YET NONE WAS SEEN. HIS ALT WAS SUCH THAT HE COULD HAVE BEEN A DANGER TO COMMERCIAL TFC DEPARTING SNA OR MIL ARRIVALS TO MCAS EL TORO. MANY TIMES, AT ALTS FROM 3-5000', COAST APCH HAS BEEN UNABLE TO SEE MY ACFT, EVEN WHEN SQUAWKING AN ASSIGNED TRANSPONDER CODE IN THIS PARTICULAR, HEAVILY TRAVELED AREA. SOMETHING SHOULD BE DONE TO IMPROVE RADAR COVERAGE IN THIS AREA BEFORE A SERIOUS ACCIDENT OCCURS.

Data retrieved from NASA's ASRS site as of August 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.