B757 crew responded to a false GPWS terrain warning.

Attributes
ACN	431634
Time
Date	199903
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : bwi.airport
State Reference	MD
Altitude	msl bound lower : 6000 msl bound upper : 6500
Person 1
Affiliation	Other
Qualification	pilot : multi engine pilot : instrument pilot : commercial
ASRS Report	431534
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : undershoot altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	aircraft equipment : gpws other flight crewa other flight crewb
Resolutory Action	flight crew : took precautionary avoidance action
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Received a GPWS warning as we were descending through approximately 6300 ft to level at 6000 ft. Both radar altimeters went to approximately 700 ft with a continuous warning of terrain. A climb was initiated and the radar altimeters went to approximately 200 ft as we passed an indicated 6500 ft in the climb. ATC was notified and vectors were given back to bwi for the approach without further incident.

Original NASA ASRS Text

Title: B757 CREW RESPONDED TO A FALSE GPWS TERRAIN WARNING.

Narrative: RECEIVED A GPWS WARNING AS WE WERE DSNDING THROUGH APPROX 6300 FT TO LEVEL AT 6000 FT. BOTH RADAR ALTIMETERS WENT TO APPROX 700 FT WITH A CONTINUOUS WARNING OF TERRAIN. A CLB WAS INITIATED AND THE RADAR ALTIMETERS WENT TO APPROX 200 FT AS WE PASSED AN INDICATED 6500 FT IN THE CLB. ATC WAS NOTIFIED AND VECTORS WERE GIVEN BACK TO BWI FOR THE APCH WITHOUT FURTHER INCIDENT.

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.