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A B757 descending from 9000 ft to 6000 ft receives a GPWS alert and climbs immediately back to 9000 ft. Aircraft was flying over the ocean at the time and terrain was not a threat. All of this under control of oak, ca, TRACON.
| Attributes | |
| ACN | 392970 |
| Time | |
| Date | 199802 |
| Day | Mon |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : pye airport : sfo |
| State Reference | CA |
| Altitude | msl bound lower : 6000 msl bound upper : 9000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : oak |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 240 flight time total : 20000 flight time type : 2000 |
| ASRS Report | 392970 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Experience | flight time last 90 days : 100 flight time total : 10200 flight time type : 1000 |
| ASRS Report | 393061 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | flight crew : took evasive action |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
We were cleared from 9000 ft to 6000 ft by sfo approach control. Upon leveling at 6000 ft, we received a 'terrain, terrain' warning on the GPWS. We immediately climbed back up to 9000 ft and advised approach control of the warning we received and our intentions. Approach control advised us that we were overwater and there was no reason for the GPWS warning we had received. We continued to the airport and landed uneventfully. Supplemental information from acn 393061: after exiting the hold, we had descended from 9000 ft to 6000 ft given a west vector. On that westerly heading, we received 2 GPWS warnings for terrain. Captain called for an immediate climb/go around thrust. I simultaneously notified ATC.
Original NASA ASRS Text
Title: A B757 DSNDING FROM 9000 FT TO 6000 FT RECEIVES A GPWS ALERT AND CLBS IMMEDIATELY BACK TO 9000 FT. ACFT WAS FLYING OVER THE OCEAN AT THE TIME AND TERRAIN WAS NOT A THREAT. ALL OF THIS UNDER CTL OF OAK, CA, TRACON.
Narrative: WE WERE CLRED FROM 9000 FT TO 6000 FT BY SFO APCH CTL. UPON LEVELING AT 6000 FT, WE RECEIVED A 'TERRAIN, TERRAIN' WARNING ON THE GPWS. WE IMMEDIATELY CLBED BACK UP TO 9000 FT AND ADVISED APCH CTL OF THE WARNING WE RECEIVED AND OUR INTENTIONS. APCH CTL ADVISED US THAT WE WERE OVERWATER AND THERE WAS NO REASON FOR THE GPWS WARNING WE HAD RECEIVED. WE CONTINUED TO THE ARPT AND LANDED UNEVENTFULLY. SUPPLEMENTAL INFO FROM ACN 393061: AFTER EXITING THE HOLD, WE HAD DSNDED FROM 9000 FT TO 6000 FT GIVEN A W VECTOR. ON THAT WESTERLY HEADING, WE RECEIVED 2 GPWS WARNINGS FOR TERRAIN. CAPT CALLED FOR AN IMMEDIATE CLB/GAR THRUST. I SIMULTANEOUSLY NOTIFIED ATC.
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.