GPWS alarm sounds during approach.

Attributes
ACN	295973
Time
Date	199502
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : san
State Reference	CA
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : san tower : ord
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 250 flight time total : 12000 flight time type : 3000
ASRS Report	295973
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Aircraft B737-300/500 flight yy sfo-san, KK45 pm. WX 15 overcast 7 mi, tops approximately 50 overcast. On approach to san (localizer 27) we were given a right turn to 240 degrees, descend and maintain 3800 ft, intercept the localizer at or above 3800 ft, cleared for the approach. Aircraft speed was 170 KTS, flaps 5 degrees descending at 500 FPM, autoplt on altitude approximately 5000 ft. When passing through 4000 ft in the clouds, the GPWS called 'terrain, terrain.' except maneuver executed and warning silenced at about 5000 ft. Notified ATC, intercepted final and landed. All clrncs were complied with and no procedural deviations were noted. Incredibly the ATC controller said a previous flight reported the same exact situation. As we spoke, the 2 aircraft ahead of us on final transmitted that they too had a GPWS warning on approach. Terrain was briefed, and the location of the highest obstacle (2791 ft) just north of vyda would coincide with actual terrain clearance of approximately 1000 ft. Controller said MVA for this sector is 3800 ft MSL. Nobody likes a GPWS warning, especially when you are operating on a normal ATC clearance with no deviation from SOP's. Perhaps this altitude is too low for this type of approach segment.

Original NASA ASRS Text

Title: GPWS ALARM SOUNDS DURING APCH.

Narrative: ACFT B737-300/500 FLT YY SFO-SAN, KK45 PM. WX 15 OVCST 7 MI, TOPS APPROX 50 OVCST. ON APCH TO SAN (LOC 27) WE WERE GIVEN A R TURN TO 240 DEGS, DSND AND MAINTAIN 3800 FT, INTERCEPT THE LOC AT OR ABOVE 3800 FT, CLRED FOR THE APCH. ACFT SPD WAS 170 KTS, FLAPS 5 DEGS DSNDING AT 500 FPM, AUTOPLT ON ALT APPROX 5000 FT. WHEN PASSING THROUGH 4000 FT IN THE CLOUDS, THE GPWS CALLED 'TERRAIN, TERRAIN.' EXCEPT MANEUVER EXECUTED AND WARNING SILENCED AT ABOUT 5000 FT. NOTIFIED ATC, INTERCEPTED FINAL AND LANDED. ALL CLRNCS WERE COMPLIED WITH AND NO PROCEDURAL DEVS WERE NOTED. INCREDIBLY THE ATC CTLR SAID A PREVIOUS FLT RPTED THE SAME EXACT SIT. AS WE SPOKE, THE 2 ACFT AHEAD OF US ON FINAL XMITTED THAT THEY TOO HAD A GPWS WARNING ON APCH. TERRAIN WAS BRIEFED, AND THE LOCATION OF THE HIGHEST OBSTACLE (2791 FT) JUST N OF VYDA WOULD COINCIDE WITH ACTUAL TERRAIN CLRNC OF APPROX 1000 FT. CTLR SAID MVA FOR THIS SECTOR IS 3800 FT MSL. NOBODY LIKES A GPWS WARNING, ESPECIALLY WHEN YOU ARE OPERATING ON A NORMAL ATC CLRNC WITH NO DEV FROM SOP'S. PERHAPS THIS ALT IS TOO LOW FOR THIS TYPE OF APCH SEGMENT.

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.