B757 flight crew has a egpws terrain warning during approach to sna.

Attributes
ACN	723133
Time
Date	200701
Local Time Of Day	1801 To 2400
Place
Locale Reference	intersection : kayoh
State Reference	CA
Altitude	msl single value : 5300
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach descent : intermediate altitude
Route In Use	arrival star : kayoh
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 6500
ASRS Report	723133
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	other spatial deviation
Independent Detector	aircraft equipment : gpws other flight crewa other flight crewb
Resolutory Action	flight crew : took precautionary avoidance action flight crew : exited adverse environment
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance Aircraft Airspace Structure
Primary Problem	Ambiguous

Narrative:

Incident occurred on flight to sna. Flight was on kayoh arrival. ATC directed flight to depart kayoh heading 260 degrees. Established on that heading at 8000 ft MSL and shortly after passing kayoh; flight was directed to descend and maintain 5000 ft MSL. At approximately 5300 ft MSL; the GPWS annunciated; 'terrain; terrain.' autoplt was disconnected and pull-up maneuver executed. Aircraft climbed to approximately 5800 ft MSL during the maneuver. After returning to 5000 ft MSL; flight continued without further incident.

Original NASA ASRS Text

Title: B757 FLT CREW HAS A EGPWS TERRAIN WARNING DURING APCH TO SNA.

Narrative: INCIDENT OCCURRED ON FLT TO SNA. FLT WAS ON KAYOH ARR. ATC DIRECTED FLT TO DEPART KAYOH HDG 260 DEGS. ESTABLISHED ON THAT HDG AT 8000 FT MSL AND SHORTLY AFTER PASSING KAYOH; FLT WAS DIRECTED TO DSND AND MAINTAIN 5000 FT MSL. AT APPROX 5300 FT MSL; THE GPWS ANNUNCIATED; 'TERRAIN; TERRAIN.' AUTOPLT WAS DISCONNECTED AND PULL-UP MANEUVER EXECUTED. ACFT CLBED TO APPROX 5800 FT MSL DURING THE MANEUVER. AFTER RETURNING TO 5000 FT MSL; FLT CONTINUED WITHOUT FURTHER INCIDENT.

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.