A B737 flight crew has TCASII RA during descent into sna.

Attributes
ACN	561537
Time
Date	200209
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sna.airport
State Reference	CA
Altitude	msl single value : 3000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon tower : sna.tower
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	approach : traffic pattern
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : sct.tracon
Operator	general aviation : personal
Make Model Name	PA-28 Cherokee/Archer II/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	descent : intermediate altitude
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial
ASRS Report	561537
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	561538
Events
Anomaly	conflict : airborne critical non adherence : far non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other controllerb other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1000 vertical : 100
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance Airspace Structure
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Socal approach had placed us on a right downwind for ILS runway 19R at sna. We were at 3000 ft, the cloud bases were about 200 ft above us. Abeam snake intersection we began to watch a TCASII target about 3 mi ahead and to the left 800 ft above us. The target was wbound crossing our nose left to right and descending to 3000 ft as it did so. When the target reached a relative position of 1 O'clock position it turned into us causing an RA to climb. I was flying and began the climb. At the same time socal called the traffic and captain replied that we were climbing to an RA. Socal then cleared us to 4000 ft and the captain saw the traffic visually. He stated that it was a blue and white piper cherokee and that it had passed us 1000 ft laterally and 100 ft vertically. The captain stated he would report an near midair collision and advised socal approach of same.

Original NASA ASRS Text

Title: A B737 FLC HAS TCASII RA DURING DSCNT INTO SNA.

Narrative: SOCAL APCH HAD PLACED US ON A R DOWNWIND FOR ILS RWY 19R AT SNA. WE WERE AT 3000 FT, THE CLOUD BASES WERE ABOUT 200 FT ABOVE US. ABEAM SNAKE INTXN WE BEGAN TO WATCH A TCASII TARGET ABOUT 3 MI AHEAD AND TO THE L 800 FT ABOVE US. THE TARGET WAS WBOUND XING OUR NOSE L TO R AND DSNDING TO 3000 FT AS IT DID SO. WHEN THE TARGET REACHED A RELATIVE POS OF 1 O'CLOCK POS IT TURNED INTO US CAUSING AN RA TO CLB. I WAS FLYING AND BEGAN THE CLB. AT THE SAME TIME SOCAL CALLED THE TFC AND CAPT REPLIED THAT WE WERE CLBING TO AN RA. SOCAL THEN CLRED US TO 4000 FT AND THE CAPT SAW THE TFC VISUALLY. HE STATED THAT IT WAS A BLUE AND WHITE PIPER CHEROKEE AND THAT IT HAD PASSED US 1000 FT LATERALLY AND 100 FT VERTLY. THE CAPT STATED HE WOULD RPT AN NMAC AND ADVISED SOCAL APCH OF SAME.

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.