Close proximity GA-small aircraft unk-aircraft in ont arsa.

Attributes
ACN	136200
Time
Date	199002
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : poc
State Reference	CA
Altitude	msl bound lower : 3700 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ont
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other descent other
Route In Use	approach : visual enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 40 flight time total : 850 flight time type : 360
ASRS Report	136200
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	Other
Miss Distance	horizontal : 0 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

It is always dangerous landing at brackett field because of its close proximity to ont. We were being vectored in for a visibility landing at brackett field. Ont approach gave us an altitude of 4000' for an approach. He was keeping us at 4000' because he had traffic coming the opp way at 3500'. He said we could intercept the localizer to find brackett field (we were unfamiliar with it). I intercepting the localizer and began to track it down, since we were on final approach for a landing to the west. I descended to 3700' and passed 200' over the opp twin engine traffic. Then the controller said we should have stayed at 4000', and he cleared us to land. I don't think the controller should have been vectoring traffic underneath us while we were on final approach.

Original NASA ASRS Text

Title: CLOSE PROX GA-SMA UNK-ACFT IN ONT ARSA.

Narrative: IT IS ALWAYS DANGEROUS LNDG AT BRACKETT FIELD BECAUSE OF ITS CLOSE PROX TO ONT. WE WERE BEING VECTORED IN FOR A VIS LNDG AT BRACKETT FIELD. ONT APCH GAVE US AN ALT OF 4000' FOR AN APCH. HE WAS KEEPING US AT 4000' BECAUSE HE HAD TFC COMING THE OPP WAY AT 3500'. HE SAID WE COULD INTERCEPT THE LOC TO FIND BRACKETT FIELD (WE WERE UNFAMILIAR WITH IT). I INTERCEPTING THE LOC AND BEGAN TO TRACK IT DOWN, SINCE WE WERE ON FINAL APCH FOR A LNDG TO THE W. I DSNDED TO 3700' AND PASSED 200' OVER THE OPP TWIN ENG TFC. THEN THE CTLR SAID WE SHOULD HAVE STAYED AT 4000', AND HE CLRED US TO LAND. I DON'T THINK THE CTLR SHOULD HAVE BEEN VECTORING TFC UNDERNEATH US WHILE WE WERE ON FINAL APCH.

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.