B757 flight crew has TCASII alert activate during climb. They descend and notify ATC.

Attributes
ACN	374350
Time
Date	199707
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : sli
State Reference	CA
Altitude	msl bound lower : 13000 msl bound upper : 13700
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	departure other enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	374350
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : nmac other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	vertical : 200

Narrative:

In VMC, climbing through 13700 ft to 17000 ft on sli 090 degree radial 40 NM, TCASII alert, followed immediately by warning to descend. Copilot followed vsi display including an increase descent warning. TCASII display showed a target within 200 ft directly above us. Advised ZLA 125.65 of descent to 13000 ft for warning. They confirmed the target which they were not controling. After clear, asked for return to climb to 17000 ft, and were cleared to FL230. Explained the descent to the flight attendants en route who had noticed the maneuver and had explained it to 1 passenger who asked that the pilot stop dive-bombing, that it was from thermals. Thank you lord for TCASII, amen.

Original NASA ASRS Text

Title: B757 FLC HAS TCASII ALERT ACTIVATE DURING CLB. THEY DSND AND NOTIFY ATC.

Narrative: IN VMC, CLBING THROUGH 13700 FT TO 17000 FT ON SLI 090 DEG RADIAL 40 NM, TCASII ALERT, FOLLOWED IMMEDIATELY BY WARNING TO DSND. COPLT FOLLOWED VSI DISPLAY INCLUDING AN INCREASE DSCNT WARNING. TCASII DISPLAY SHOWED A TARGET WITHIN 200 FT DIRECTLY ABOVE US. ADVISED ZLA 125.65 OF DSCNT TO 13000 FT FOR WARNING. THEY CONFIRMED THE TARGET WHICH THEY WERE NOT CTLING. AFTER CLR, ASKED FOR RETURN TO CLB TO 17000 FT, AND WERE CLRED TO FL230. EXPLAINED THE DSCNT TO THE FLT ATTENDANTS ENRTE WHO HAD NOTICED THE MANEUVER AND HAD EXPLAINED IT TO 1 PAX WHO ASKED THAT THE PLT STOP DIVE-BOMBING, THAT IT WAS FROM THERMALS. THANK YOU LORD FOR TCASII, AMEN.

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.