A B737-400 flight crew experience a TCASII RA in sct airspace.

Attributes
ACN	581813
Time
Date	200305
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : javsi
State Reference	CA
Altitude	msl single value : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : sct.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
ASRS Report	581813
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne critical other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action flight crew : took precautionary avoidance action
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	Airspace Structure

Narrative:

We were cleared to descend to 2500 ft after smo VOR on a 070 degree heading. Flying through broken clouds. Somewhere in the vicinity of javsi (over downtown la) approach advised numerous VFR aircraft below the class B airspace. I could see 3 targets on the TCASII display, all about 600 ft below us. One target began climbing and came within 400 ft of us. We received an RA and responded to it by climbing. We never saw the other aircraft. We advised ATC and had a brief discussion as to why the controller descended us so close to known traffic. The controller responded that he had to descend us and that he would explain if I called him on the telephone. I didn't call. I am sure ATC has a good reason for descending aircraft so low so far from the runway, however good sense dictates that you should not descend aircraft in IMC conditions so close to VFR traffic. ATC's procedures put our aircraft in harm's way unnecessarily during a high workload period, a bad combination.

Original NASA ASRS Text

Title: A B737-400 FLT CREW EXPERIENCE A TCASII RA IN SCT AIRSPACE.

Narrative: WE WERE CLRED TO DSND TO 2500 FT AFTER SMO VOR ON A 070 DEG HDG. FLYING THROUGH BROKEN CLOUDS. SOMEWHERE IN THE VICINITY OF JAVSI (OVER DOWNTOWN LA) APCH ADVISED NUMEROUS VFR ACFT BELOW THE CLASS B AIRSPACE. I COULD SEE 3 TARGETS ON THE TCASII DISPLAY, ALL ABOUT 600 FT BELOW US. ONE TARGET BEGAN CLBING AND CAME WITHIN 400 FT OF US. WE RECEIVED AN RA AND RESPONDED TO IT BY CLBING. WE NEVER SAW THE OTHER ACFT. WE ADVISED ATC AND HAD A BRIEF DISCUSSION AS TO WHY THE CTLR DSNDED US SO CLOSE TO KNOWN TFC. THE CTLR RESPONDED THAT HE HAD TO DSND US AND THAT HE WOULD EXPLAIN IF I CALLED HIM ON THE TELEPHONE. I DIDN'T CALL. I AM SURE ATC HAS A GOOD REASON FOR DSNDING ACFT SO LOW SO FAR FROM THE RWY, HOWEVER GOOD SENSE DICTATES THAT YOU SHOULD NOT DSND ACFT IN IMC CONDITIONS SO CLOSE TO VFR TFC. ATC'S PROCS PUT OUR ACFT IN HARM'S WAY UNNECESSARILY DURING A HIGH WORKLOAD PERIOD, A BAD COMBINATION.

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.