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An air carrier SF34 flight crew gets a false GPWS terrain warning. The flight crew reacts to the warning by reconfirming with the controller that they are at the proper altitude and clear of terrain.
| Attributes | |
| ACN | 393042 |
| Time | |
| Date | 199801 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : elm |
| State Reference | NY |
| Altitude | msl bound lower : 3300 msl bound upper : 3300 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : elm |
| Operator | common carrier : air carrier |
| Make Model Name | SF 340A |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : cfi pilot : atp pilot : instrument pilot : commercial |
| Experience | flight time last 90 days : 270 flight time total : 3700 flight time type : 1300 |
| ASRS Report | 393042 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
Our flight was from bgm-elm. We descended from cruise altitude to 3300 ft MSL. We were receiving radar vectors for the ILS runway 24 into elm. The GPWS terrain advisory went off and continued to go off until we were on the ground. We were IMC for about 1 min before joining the GS. I immediately requested a verification of our altitude from approach. They verified 3300 ft MSL and subsequently cleared us for the approach. False terrain advisories in saab 'a' model aircraft are quite common. Common enough that we seldom believe them. This is a very dangerous situation to be in. Knowing the GPWS is wrong yet it still going off. I've decided that in the future, even though I know the warning to be false, I will go around and proceed to my alternate airport. Not a good situation either way.
Original NASA ASRS Text
Title: AN ACR SF34 FLC GETS A FALSE GPWS TERRAIN WARNING. THE FLC REACTS TO THE WARNING BY RECONFIRMING WITH THE CTLR THAT THEY ARE AT THE PROPER ALT AND CLR OF TERRAIN.
Narrative: OUR FLT WAS FROM BGM-ELM. WE DSNDED FROM CRUISE ALT TO 3300 FT MSL. WE WERE RECEIVING RADAR VECTORS FOR THE ILS RWY 24 INTO ELM. THE GPWS TERRAIN ADVISORY WENT OFF AND CONTINUED TO GO OFF UNTIL WE WERE ON THE GND. WE WERE IMC FOR ABOUT 1 MIN BEFORE JOINING THE GS. I IMMEDIATELY REQUESTED A VERIFICATION OF OUR ALT FROM APCH. THEY VERIFIED 3300 FT MSL AND SUBSEQUENTLY CLRED US FOR THE APCH. FALSE TERRAIN ADVISORIES IN SAAB 'A' MODEL ACFT ARE QUITE COMMON. COMMON ENOUGH THAT WE SELDOM BELIEVE THEM. THIS IS A VERY DANGEROUS SIT TO BE IN. KNOWING THE GPWS IS WRONG YET IT STILL GOING OFF. I'VE DECIDED THAT IN THE FUTURE, EVEN THOUGH I KNOW THE WARNING TO BE FALSE, I WILL GAR AND PROCEED TO MY ALTERNATE ARPT. NOT A GOOD SIT EITHER WAY.
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.