TCASII RA, sight traffic and turn away.

Attributes
ACN	233070
Time
Date	199302
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : pdz
State Reference	CA
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ont
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent : approach
Route In Use	arrival : profile descent
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : atp pilot : cfi
Experience	flight time last 90 days : 200 flight time total : 9000 flight time type : 2200
ASRS Report	233070
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : clearance other anomaly other other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 3000 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

On approach to airport, marginal visibility, WX radar on for light precipitation, TCASII issued a TA, radar was operational on 20 mi range and target was observed somewhere near center of aircraft. Was busy setting up for approach and talking to approach control. Second TA issued by TCASII. Immediately went to 5 mi TCASII only mode and observed target moving from 1-2 O'clock, less than 1 mi. Went visual and observed small aircraft off right at same altitude. Added thrust and banked left deviating from approach instructions. Advised ATC and returned to profile when clear of traffic. ATC was very busy, however, they reported no traffic at our altitude and gave no TA's. TCASII showed no altitude reporting on target. Have had numerous close calls in this area due to numerous airports operating in area, and several unidentified aircraft. Also, TCASII software would be very much more useful if, when a TA is issued, it would automatically switch to TCASII only 5 mi range, as this is the most useful display when searching for aircraft. In TCASII WX mode in greater than 10 mi traffic target readout relative to aircraft is useless.

Original NASA ASRS Text

Title: TCASII RA, SIGHT TFC AND TURN AWAY.

Narrative: ON APCH TO ARPT, MARGINAL VISIBILITY, WX RADAR ON FOR LIGHT PRECIPITATION, TCASII ISSUED A TA, RADAR WAS OPERATIONAL ON 20 MI RANGE AND TARGET WAS OBSERVED SOMEWHERE NEAR CTR OF ACFT. WAS BUSY SETTING UP FOR APCH AND TALKING TO APCH CTL. SECOND TA ISSUED BY TCASII. IMMEDIATELY WENT TO 5 MI TCASII ONLY MODE AND OBSERVED TARGET MOVING FROM 1-2 O'CLOCK, LESS THAN 1 MI. WENT VISUAL AND OBSERVED SMALL ACFT OFF R AT SAME ALT. ADDED THRUST AND BANKED L DEVIATING FROM APCH INSTRUCTIONS. ADVISED ATC AND RETURNED TO PROFILE WHEN CLR OF TFC. ATC WAS VERY BUSY, HOWEVER, THEY RPTED NO TFC AT OUR ALT AND GAVE NO TA'S. TCASII SHOWED NO ALT RPTING ON TARGET. HAVE HAD NUMEROUS CLOSE CALLS IN THIS AREA DUE TO NUMEROUS ARPTS OPERATING IN AREA, AND SEVERAL UNIDENTIFIED ACFT. ALSO, TCASII SOFTWARE WOULD BE VERY MUCH MORE USEFUL IF, WHEN A TA IS ISSUED, IT WOULD AUTOMATICALLY SWITCH TO TCASII ONLY 5 MI RANGE, AS THIS IS THE MOST USEFUL DISPLAY WHEN SEARCHING FOR ACFT. IN TCASII WX MODE IN GREATER THAN 10 MI TFC TARGET READOUT RELATIVE TO ACFT IS USELESS.

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.