Large transport took evasive action to assure clearance with small transport.

Attributes
ACN	82133
Time
Date	198802
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : fim
State Reference	CA
Altitude	msl bound lower : 1200 msl bound upper : 1200
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : lax
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	arrival : profile descent
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 6000 flight time type : 2000
ASRS Report	82133
Person 2
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 2000 vertical : 0
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

On profile descent around 12000', I saw a light twin banking sharply at about the 2-3 O'clock position. The twin had obviously seen us and was turning to avoid, but I took control of the aircraft and banked left to ensure sep. We asked center if he was showing the aircraft on radar, and he showed nothing but said he would look for him. We were then handed off to approach. The traffic was difficult to see due to low sun at the 1-2 O'clock position and haze. Mandatory xponders with altitude encoding capability on all aircraft would have alerted ATC to the potential conflict, and would have alerted us to the problem much sooner than visibility acquisition provided.

Original NASA ASRS Text

Title: LGT TOOK EVASIVE ACTION TO ASSURE CLRNC WITH SMT.

Narrative: ON PROFILE DSCNT AROUND 12000', I SAW A LIGHT TWIN BANKING SHARPLY AT ABOUT THE 2-3 O'CLOCK POS. THE TWIN HAD OBVIOUSLY SEEN US AND WAS TURNING TO AVOID, BUT I TOOK CTL OF THE ACFT AND BANKED LEFT TO ENSURE SEP. WE ASKED CENTER IF HE WAS SHOWING THE ACFT ON RADAR, AND HE SHOWED NOTHING BUT SAID HE WOULD LOOK FOR HIM. WE WERE THEN HANDED OFF TO APCH. THE TFC WAS DIFFICULT TO SEE DUE TO LOW SUN AT THE 1-2 O'CLOCK POS AND HAZE. MANDATORY XPONDERS WITH ALT ENCODING CAPABILITY ON ALL ACFT WOULD HAVE ALERTED ATC TO THE POTENTIAL CONFLICT, AND WOULD HAVE ALERTED US TO THE PROB MUCH SOONER THAN VIS ACQUISITION PROVIDED.

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.