FA22 crew had an near midair collision with an small aircraft in IMC conditions near cno.

Attributes
ACN	436076
Time
Date	199905
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : cno.airport
State Reference	CA
Altitude	msl single value : 3000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	SA-227 AC Metro III
Operating Under FAR Part	Part 135
Navigation In Use	ils other localizer
Flight Phase	descent : approach
Route In Use	approach : instrument non precision
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 120 flight time total : 2900 flight time type : 50
ASRS Report	436076
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	airspace violation : entry conflict : nmac inflight encounter : vfr in imc non adherence : far non adherence : published procedure
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	vertical : 200
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

I was first officer (PF) of part 135 passenger flight. We were on IFR flight plan tracking hawthorne localizer runway 25. We were in and out of clouds. Received tcasi TA, aircraft within 1 mi, 400 ft below and climbing. I tried to acquire aircraft visually to our right. When tcasi TA indicated 200 ft separation and climbing, we began a climbing left turn off localizer. No call from socal approach control regarding aircraft. Just as we began evasive action, ATC gave us a frequency change. We did not continue to track tcasi target due to workload of localizer approach and conditions. Crew was very familiar with area, this approach routing, and traffic hazards. We believe other aircraft was trying to depart chino area VFR and was flying between/around layers. We had numerous targets depicted on tcasi at the time. Collision averted by tcasi alert, effective monitoring by captain, good crew coordination and timely evasive action.

Original NASA ASRS Text

Title: FA22 CREW HAD AN NMAC WITH AN SMA IN IMC CONDITIONS NEAR CNO.

Narrative: I WAS FO (PF) OF PART 135 PAX FLT. WE WERE ON IFR FLT PLAN TRACKING HAWTHORNE LOC RWY 25. WE WERE IN AND OUT OF CLOUDS. RECEIVED TCASI TA, ACFT WITHIN 1 MI, 400 FT BELOW AND CLBING. I TRIED TO ACQUIRE ACFT VISUALLY TO OUR R. WHEN TCASI TA INDICATED 200 FT SEPARATION AND CLBING, WE BEGAN A CLBING L TURN OFF LOC. NO CALL FROM SOCAL APCH CTL REGARDING ACFT. JUST AS WE BEGAN EVASIVE ACTION, ATC GAVE US A FREQ CHANGE. WE DID NOT CONTINUE TO TRACK TCASI TARGET DUE TO WORKLOAD OF LOC APCH AND CONDITIONS. CREW WAS VERY FAMILIAR WITH AREA, THIS APCH ROUTING, AND TFC HAZARDS. WE BELIEVE OTHER ACFT WAS TRYING TO DEPART CHINO AREA VFR AND WAS FLYING BTWN/AROUND LAYERS. WE HAD NUMEROUS TARGETS DEPICTED ON TCASI AT THE TIME. COLLISION AVERTED BY TCASI ALERT, EFFECTIVE MONITORING BY CAPT, GOOD CREW COORD AND TIMELY EVASIVE ACTION.

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.