B757 on vectors from sct to sna at approximately 5000 ft received TCASII TA followed with GPWS event...

Attributes
ACN	638005
Time
Date	200411
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : kayoh
State Reference	CA
Altitude	msl single value : 5000
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : kayoh 4
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 200 flight time total : 16000 flight time type : 2000
ASRS Report	638005
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : published procedure other anomaly other
Independent Detector	aircraft equipment : gpws aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Airspace Structure Navigational Facility Aircraft ATC Human Performance
Primary Problem	Airspace Structure

Narrative:

Talking with socal approach, aircraft X was cleared direct kayoh intersection. Our initial altitude clearance was to 5200 ft, and then just east of kayoh, clearance was to 5000 ft. TCASII gave us a 'traffic, traffic,' and we noticed the yellow symbol on HSI with no altitude with it. The symbol changed to a white diamond, and we asked approach about the traffic. Socal said it was a transponder on top of a hill. Shortly thereafter, the GPWS gave us a 'terrain, terrain, pull up.' just after (about 5100 ft) while pulling up, the warning stopped. We were in clear VMC with cloud deck below, and no terrain in sight. Called socal approach after landing at sna, and they said they are having problems in the area of the transponder on the hill, and appreciated the report.

Original NASA ASRS Text

Title: B757 ON VECTORS FROM SCT TO SNA AT APPROX 5000 FT RECEIVED TCASII TA FOLLOWED WITH GPWS EVENT.

Narrative: TALKING WITH SOCAL APCH, ACFT X WAS CLRED DIRECT KAYOH INTXN. OUR INITIAL ALT CLRNC WAS TO 5200 FT, AND THEN JUST E OF KAYOH, CLRNC WAS TO 5000 FT. TCASII GAVE US A 'TFC, TFC,' AND WE NOTICED THE YELLOW SYMBOL ON HSI WITH NO ALT WITH IT. THE SYMBOL CHANGED TO A WHITE DIAMOND, AND WE ASKED APCH ABOUT THE TFC. SOCAL SAID IT WAS A XPONDER ON TOP OF A HILL. SHORTLY THEREAFTER, THE GPWS GAVE US A 'TERRAIN, TERRAIN, PULL UP.' JUST AFTER (ABOUT 5100 FT) WHILE PULLING UP, THE WARNING STOPPED. WE WERE IN CLR VMC WITH CLOUD DECK BELOW, AND NO TERRAIN IN SIGHT. CALLED SOCAL APCH AFTER LNDG AT SNA, AND THEY SAID THEY ARE HAVING PROBS IN THE AREA OF THE XPONDER ON THE HILL, AND APPRECIATED THE RPT.

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.