Narrative:

On a vector to oak international airport, ca, approach control, bay approach began a vector from the STAR published for oak airport. The vector took the flight from den, co, over the hills east of oak airport. At a point in the descent from 8000 ft MSL to 5000 ft, over mt. Diablo the aircraft GPWS system (#4) began and calculated a collision closure rate that resulted in a GPWS warning indication in the cockpit and an indication of radar altimeter going through 1300 ft to go to the ground AGL. At the first warning of GPWS I initiated the crew to accomplish the approved procedure for this situation. Autoplt disconnect, aircraft pitch 15 degree up, firewall power and climb immediately. Flight departed 5000 ft MSL to a safe VFR altitude of 6500 ft MSL. At this point, flight could not communicate the altitude deviation due to heavy and seemingly impossible ATC radio saturation. Eventfully the controller was informed and immediately the bay approach controller handed us off to the next bay approach controller for the final turn to oak runway 11 ILS. This controller was informed of the situation and then cleared flight for the ILS to oak runway 11. After landing, I contacted the oak tower and coordinated a communication with bay approach control supervisor and discussed the event and the conditions and her feeling about what had happened. Vectoring of aircraft in this area should be stopped immediately.

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Original NASA ASRS Text

Title: ACR LGT REVERSED DSCNT IN RESPONSE TO GPWS WARNING, ACFT WAS APCHING MT, DIABLO DSNDING TO 5000 FT ON RADAR VECTORS.

Narrative: ON A VECTOR TO OAK INTL ARPT, CA, APCH CTL, BAY APCH BEGAN A VECTOR FROM THE STAR PUBLISHED FOR OAK ARPT. THE VECTOR TOOK THE FLT FROM DEN, CO, OVER THE HILLS E OF OAK ARPT. AT A POINT IN THE DSCNT FROM 8000 FT MSL TO 5000 FT, OVER MT. DIABLO THE ACFT GPWS SYS (#4) BEGAN AND CALCULATED A COLLISION CLOSURE RATE THAT RESULTED IN A GPWS WARNING INDICATION IN THE COCKPIT AND AN INDICATION OF RADAR ALTIMETER GOING THROUGH 1300 FT TO GO TO THE GND AGL. AT THE FIRST WARNING OF GPWS I INITIATED THE CREW TO ACCOMPLISH THE APPROVED PROC FOR THIS SITUATION. AUTOPLT DISCONNECT, ACFT PITCH 15 DEG UP, FIREWALL PWR AND CLB IMMEDIATELY. FLT DEPARTED 5000 FT MSL TO A SAFE VFR ALT OF 6500 FT MSL. AT THIS POINT, FLT COULD NOT COMMUNICATE THE ALTDEV DUE TO HVY AND SEEMINGLY IMPOSSIBLE ATC RADIO SATURATION. EVENTFULLY THE CTLR WAS INFORMED AND IMMEDIATELY THE BAY APCH CTLR HANDED US OFF TO THE NEXT BAY APCH CTLR FOR THE FINAL TURN TO OAK RWY 11 ILS. THIS CTLR WAS INFORMED OF THE SITUATION AND THEN CLRED FLT FOR THE ILS TO OAK RWY 11. AFTER LNDG, I CONTACTED THE OAK TWR AND COORDINATED A COM WITH BAY APCH CTL SUPVR AND DISCUSSED THE EVENT AND THE CONDITIONS AND HER FEELING ABOUT WHAT HAD HAPPENED. VECTORING OF ACFT IN THIS AREA SHOULD BE STOPPED IMMEDIATELY.

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.