Narrative:

We were flying direct to the crw runway 23 FAF under the control of crw approach. We were at low altitude and had been given further descent clearance to 2900 ft. As we descended over dark, mostly unlighted mountainous terrain, the aircraft's GPWS sounded. Although visibility was good, the lack of illumination prevented us from positively knowing whether or not the GPWS warning was real or false. Given that uncertainty, and in accordance with company policy, the captain immediately began a climb so as to silence the GPWS. At the same time we radioed the controller of our change in altitude, that we were climbing to 4000 ft. After chastising us for changing our altitude without permission, our explanation did not appear to be acceptable to him, he then reclred us to 4000 ft.

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Original NASA ASRS Text

Title: MLG RECEIVED GPWS ALERT DURING DSCNT NON ADHERENCE TO ATC CLRNC CLB.

Narrative: WE WERE FLYING DIRECT TO THE CRW RWY 23 FAF UNDER THE CTL OF CRW APCH. WE WERE AT LOW ALT AND HAD BEEN GIVEN FURTHER DSCNT CLRNC TO 2900 FT. AS WE DSNDED OVER DARK, MOSTLY UNLIGHTED MOUNTAINOUS TERRAIN, THE ACFT'S GPWS SOUNDED. ALTHOUGH VISIBILITY WAS GOOD, THE LACK OF ILLUMINATION PREVENTED US FROM POSITIVELY KNOWING WHETHER OR NOT THE GPWS WARNING WAS REAL OR FALSE. GIVEN THAT UNCERTAINTY, AND IN ACCORDANCE WITH COMPANY POLICY, THE CAPT IMMEDIATELY BEGAN A CLB SO AS TO SILENCE THE GPWS. AT THE SAME TIME WE RADIOED THE CTLR OF OUR CHANGE IN ALT, THAT WE WERE CLBING TO 4000 FT. AFTER CHASTISING US FOR CHANGING OUR ALT WITHOUT PERMISSION, OUR EXPLANATION DID NOT APPEAR TO BE ACCEPTABLE TO HIM, HE THEN RECLRED US TO 4000 FT.

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.