Narrative:

Jawws 1 arrival to sjc, established on the oak 138 degree radial at approximately 30-40 DME, first officer flying, WX solid IMC, aircraft on autoplt, speed 250 KTS, vertical speed 700 FPM down, cleared to 4500 ft, sjc altimeter 30.13, time approximately XA40. While descending through approximately 4800-4700 ft, we received a GPWS 'terrain' warning. First officer executed escape maneuver by smoothly and rapidly advancing throttles to the mechanical stops and rotating aircraft pitch to 15 degrees nose up. Warning continued while climbing at 300-500 FPM. After warning stopped, aircraft was leveled at 7000 ft and bay approach was advised. We were informed that 4500 ft was the MVA for that sector. No other aircraft were observed on TCASII in our area. Bay approach cleared us to 4000 ft and we proceeded with radar vectors to the visual approach runway 12R. Because of IMC conditions, I could not confirm if warning was false, so I assumed it was real. Aircraft was written up because I cannot confirm or deny that the engines were not overtemped or oversped. Callback conversation with bay TRACON revealed the following information: called bay TRACON and spoke to a specialist regarding the GPWS problem at sjc. Specialist said they were aware of the problem and also had correspondence with alpa and the FAA regional office. As of this time they do not have a solution, but it may be a software problem with the airborne equipment (over sensitive to changing terrain). Other facilities, such as pdx and den, are also reporting the same. The specialist claims that no procedural changes have been made at bay.

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Original NASA ASRS Text

Title: AN ACR FLC HAS A GPWS TERRAIN WARNING WHILE DSNDING ON THE JAWWS 1 ARR. THE FLC PROPERLY EXECUTED AN EVASIVE CLB TO AVOID TERRAIN. THE MVA FOR THE AREA WAS 4500 FT.

Narrative: JAWWS 1 ARR TO SJC, ESTABLISHED ON THE OAK 138 DEG RADIAL AT APPROX 30-40 DME, FO FLYING, WX SOLID IMC, ACFT ON AUTOPLT, SPD 250 KTS, VERT SPD 700 FPM DOWN, CLRED TO 4500 FT, SJC ALTIMETER 30.13, TIME APPROX XA40. WHILE DSNDING THROUGH APPROX 4800-4700 FT, WE RECEIVED A GPWS 'TERRAIN' WARNING. FO EXECUTED ESCAPE MANEUVER BY SMOOTHLY AND RAPIDLY ADVANCING THROTTLES TO THE MECHANICAL STOPS AND ROTATING ACFT PITCH TO 15 DEGS NOSE UP. WARNING CONTINUED WHILE CLBING AT 300-500 FPM. AFTER WARNING STOPPED, ACFT WAS LEVELED AT 7000 FT AND BAY APCH WAS ADVISED. WE WERE INFORMED THAT 4500 FT WAS THE MVA FOR THAT SECTOR. NO OTHER ACFT WERE OBSERVED ON TCASII IN OUR AREA. BAY APCH CLRED US TO 4000 FT AND WE PROCEEDED WITH RADAR VECTORS TO THE VISUAL APCH RWY 12R. BECAUSE OF IMC CONDITIONS, I COULD NOT CONFIRM IF WARNING WAS FALSE, SO I ASSUMED IT WAS REAL. ACFT WAS WRITTEN UP BECAUSE I CANNOT CONFIRM OR DENY THAT THE ENGS WERE NOT OVERTEMPED OR OVERSPED. CALLBACK CONVERSATION WITH BAY TRACON REVEALED THE FOLLOWING INFO: CALLED BAY TRACON AND SPOKE TO A SPECIALIST REGARDING THE GPWS PROB AT SJC. SPECIALIST SAID THEY WERE AWARE OF THE PROB AND ALSO HAD CORRESPONDENCE WITH ALPA AND THE FAA REGIONAL OFFICE. AS OF THIS TIME THEY DO NOT HAVE A SOLUTION, BUT IT MAY BE A SOFTWARE PROB WITH THE AIRBORNE EQUIP (OVER SENSITIVE TO CHANGING TERRAIN). OTHER FACILITIES, SUCH AS PDX AND DEN, ARE ALSO RPTING THE SAME. THE SPECIALIST CLAIMS THAT NO PROCEDURAL CHANGES HAVE BEEN MADE AT BAY.

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.