B737 flight crew receives a GPWS 'terrain warning' during the arrival into oak. Flight crew executes...

Attributes
ACN	686143
Time
Date	200602
Place
Locale Reference	intersection : sunol
State Reference	CA
Altitude	msl single value : 5000
Environment
Flight Conditions	IMC
Aircraft 1
Controlling Facilities	tracon : n90.tracon
Operator	common carrier : air carrier
Make Model Name	B737-500
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach
Route In Use	arrival star : panoche2
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 3250 flight time total : 10475 flight time type : 3250
ASRS Report	686143
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	other anomaly other
Independent Detector	aircraft equipment : gpws other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : took precautionary avoidance action
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Aircraft Airspace Structure Environmental Factor Flight Crew Human Performance Weather
Primary Problem	Ambiguous

Narrative:

Originally filed for panoche 2 arrival. Changed to commo 1 arrival. Changed back to panoche 2; but told oak still landing runway 11. Instructed to cross bored intersection at 10000 ft. Entered IMC at 9500 ft. Later cleared to 7000 ft; then 6000 ft. Cleared to 5000 ft between bushy and sunol intxns. Heard another aircraft cleared for runway 29 approach. Captain requested landing runway. Norcal told us runway 29. Approaching sunol radio altimeter indicated '2500.' at approximately 5100 ft; during leveloff; GPWS warned 'terrain; terrain.' RA indicated approximately 2200 ft. Terrain map showed solid green returns below; no yellow or red returns. Initiated terrain avoidance maneuver. Climbed to 6000 ft. Advised norcal of GPWS climb. Norcal stated MVA at our position was 5000 ft. Charted MSA on ILS runway 29 approach plate is 5100 ft. After landing; captain called ATC supervisor. Supervisor said no terrain in front of us; MVA is 5000 ft; and this happens every few months. Said they had reviewed tapes and both controller and crew had performed properly. Suggested that possible high descent rate may have caused GPWS warning. Do not think this was the case -- aircraft was already initiating leveloff when warning occurred.

Original NASA ASRS Text

Title: B737 FLT CREW RECEIVES A GPWS 'TERRAIN WARNING' DURING THE ARR INTO OAK. FLT CREW EXECUTES AVOIDANCE MANEUVER.

Narrative: ORIGINALLY FILED FOR PANOCHE 2 ARR. CHANGED TO COMMO 1 ARR. CHANGED BACK TO PANOCHE 2; BUT TOLD OAK STILL LNDG RWY 11. INSTRUCTED TO CROSS BORED INTXN AT 10000 FT. ENTERED IMC AT 9500 FT. LATER CLRED TO 7000 FT; THEN 6000 FT. CLRED TO 5000 FT BTWN BUSHY AND SUNOL INTXNS. HEARD ANOTHER ACFT CLRED FOR RWY 29 APCH. CAPT REQUESTED LNDG RWY. NORCAL TOLD US RWY 29. APCHING SUNOL RADIO ALTIMETER INDICATED '2500.' AT APPROX 5100 FT; DURING LEVELOFF; GPWS WARNED 'TERRAIN; TERRAIN.' RA INDICATED APPROX 2200 FT. TERRAIN MAP SHOWED SOLID GREEN RETURNS BELOW; NO YELLOW OR RED RETURNS. INITIATED TERRAIN AVOIDANCE MANEUVER. CLBED TO 6000 FT. ADVISED NORCAL OF GPWS CLB. NORCAL STATED MVA AT OUR POS WAS 5000 FT. CHARTED MSA ON ILS RWY 29 APCH PLATE IS 5100 FT. AFTER LNDG; CAPT CALLED ATC SUPVR. SUPVR SAID NO TERRAIN IN FRONT OF US; MVA IS 5000 FT; AND THIS HAPPENS EVERY FEW MONTHS. SAID THEY HAD REVIEWED TAPES AND BOTH CTLR AND CREW HAD PERFORMED PROPERLY. SUGGESTED THAT POSSIBLE HIGH DSCNT RATE MAY HAVE CAUSED GPWS WARNING. DO NOT THINK THIS WAS THE CASE -- ACFT WAS ALREADY INITIATING LEVELOFF WHEN WARNING OCCURRED.

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.

B737 flight crew receives a GPWS 'terrain warning' during the arrival into oak. Flight crew executes avoidance maneuver.