Close proximity air carrier-medium large transport GA-small aircraft 20 west of ont.

Attributes
ACN	104025
Time
Date	198902
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : sna airport : ont
State Reference	CA
Altitude	msl bound lower : 8000 msl bound upper : 8400
Environment
Flight Conditions	Marginal
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : ont
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : private pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time total : 6500
ASRS Report	103025
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Miss Distance	horizontal : 300 vertical : 400
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

While on vectors from approach control level at 8000', the controller stated that he had an aircraft alert at our 10 O'clock position less than a mi unverified at 8400'. We looked to the 10 O'clock position just as a single engine low wing aircraft passed over head and slightly to our rear from left to right. The aircraft passed within 300-400' of our aircraft and we had no time to take evasive action. The controller possibly could have given us an earlier warning if his workload were not so great. Numerous aircraft were being vectored by the controller and VFR targets were everywhere.

Original NASA ASRS Text

Title: CLOSE PROX ACR-MLG GA-SMA 20 WEST OF ONT.

Narrative: WHILE ON VECTORS FROM APCH CTL LEVEL AT 8000', THE CTLR STATED THAT HE HAD AN ACFT ALERT AT OUR 10 O'CLOCK POS LESS THAN A MI UNVERIFIED AT 8400'. WE LOOKED TO THE 10 O'CLOCK POS JUST AS A SINGLE ENG LOW WING ACFT PASSED OVER HEAD AND SLIGHTLY TO OUR REAR FROM LEFT TO RIGHT. THE ACFT PASSED WITHIN 300-400' OF OUR ACFT AND WE HAD NO TIME TO TAKE EVASIVE ACTION. THE CTLR POSSIBLY COULD HAVE GIVEN US AN EARLIER WARNING IF HIS WORKLOAD WERE NOT SO GREAT. NUMEROUS ACFT WERE BEING VECTORED BY THE CTLR AND VFR TARGETS WERE EVERYWHERE.

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.