B737-700 flight crew has a TCAS RA during sadde six arrival to lax.

Attributes
ACN	722929
Time
Date	200701
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lax.airport
State Reference	CA
Altitude	msl single value : 14000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla.artcc
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 246
ASRS Report	722929
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 38 flight time type : 30
ASRS Report	722930
Events
Anomaly	conflict : airborne critical non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : took precautionary avoidance action
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

On sadde six arrival to lax cleared to cross symon at 12000 ft. Notified by ZLA of VFR traffic at 11-12 O'clock position; at 14000 ft MSL. Maintained normal descent gradient to cross symon at 12000 ft. Received TCAS TA; and shortly thereafter; an RA to maintain vertical speed (approximately 2000 FPM descent). I acquired visual contact of the traffic at 12 O'clock position; and as we descended through the traffic's altitude and were below the other aircraft. It appeared to me as if he began a descent and we received a TCAS RA to climb. Since the rate of closure was high and we were already below that aircraft and descending; I maintained the descent to avoid pulling back up through the conflicting traffic's altitude and avoid an near midair collision. We were able to maintain the ATC clearance and comply with the RA guidance except with respect to reversing the descent when below and clear of the other traffic. ATC could have directed us to level off above the traffic and then delete the symon crossing restr; I could also have either increased my rate of descent to get below the traffic or leveled off above and requested relief for the symon crossing restr.

Original NASA ASRS Text

Title: B737-700 FLT CREW HAS A TCAS RA DURING SADDE SIX ARR TO LAX.

Narrative: ON SADDE SIX ARR TO LAX CLRED TO CROSS SYMON AT 12000 FT. NOTIFIED BY ZLA OF VFR TFC AT 11-12 O'CLOCK POS; AT 14000 FT MSL. MAINTAINED NORMAL DSCNT GRADIENT TO CROSS SYMON AT 12000 FT. RECEIVED TCAS TA; AND SHORTLY THEREAFTER; AN RA TO MAINTAIN VERT SPD (APPROX 2000 FPM DSCNT). I ACQUIRED VISUAL CONTACT OF THE TFC AT 12 O'CLOCK POS; AND AS WE DSNDED THROUGH THE TFC'S ALT AND WERE BELOW THE OTHER ACFT. IT APPEARED TO ME AS IF HE BEGAN A DSCNT AND WE RECEIVED A TCAS RA TO CLB. SINCE THE RATE OF CLOSURE WAS HIGH AND WE WERE ALREADY BELOW THAT ACFT AND DSNDING; I MAINTAINED THE DSCNT TO AVOID PULLING BACK UP THROUGH THE CONFLICTING TFC'S ALT AND AVOID AN NMAC. WE WERE ABLE TO MAINTAIN THE ATC CLRNC AND COMPLY WITH THE RA GUIDANCE EXCEPT WITH RESPECT TO REVERSING THE DSCNT WHEN BELOW AND CLR OF THE OTHER TFC. ATC COULD HAVE DIRECTED US TO LEVEL OFF ABOVE THE TFC AND THEN DELETE THE SYMON XING RESTR; I COULD ALSO HAVE EITHER INCREASED MY RATE OF DSCNT TO GET BELOW THE TFC OR LEVELED OFF ABOVE AND REQUESTED RELIEF FOR THE SYMON XING RESTR.

Data retrieved from NASA's ASRS site as of January 2009 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.