Narrative:

We were flying at 10000', 250 KTS, 10 mi northeast of dulles on a heading of 260 degrees attempting to avoid a line of thunderstorms in our approach for landing at dulles. West/O warning in moderate to heavy rain, the GPWS went off with terrain and pull up warning. Full forward thrust was applied and the nose raised to about 20 degrees. The warning continued to about 13500'. We were climbing at about 6000 FPM. By the time we could level off we were at 15500' and 180 KTS. ATC was advised of our actions within the first 30 seconds and again after the warnings stopped. After the second notification we were given a heading and altitude at our discretion for radar vectors to an ILS at dulles. We executed the above procedures as per training dictates. The 3 cockpit crew members, in retrospect, could not justify the warnings for the regime of flight (i.e., 10000', no terrain problems, at least 5000' above any local MEA), but being totally IFR we reacted as trained and climbed out of danger. The captain's radio altimeter read 700' when the warning sounded and went to 500' before increasing. This may have been the cause of the problem.

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Original NASA ASRS Text

Title: ACR HVT LEVEL AT 10000' TO IAD EXPERIENCES FALSE GND PROX WARNING INDICATION AND INITIATES EMERGENCY CLIMB TO 15500'.

Narrative: WE WERE FLYING AT 10000', 250 KTS, 10 MI NE OF DULLES ON A HDG OF 260 DEGS ATTEMPTING TO AVOID A LINE OF TSTMS IN OUR APCH FOR LNDG AT DULLES. W/O WARNING IN MODERATE TO HEAVY RAIN, THE GPWS WENT OFF WITH TERRAIN AND PULL UP WARNING. FULL FORWARD THRUST WAS APPLIED AND THE NOSE RAISED TO ABOUT 20 DEGS. THE WARNING CONTINUED TO ABOUT 13500'. WE WERE CLBING AT ABOUT 6000 FPM. BY THE TIME WE COULD LEVEL OFF WE WERE AT 15500' AND 180 KTS. ATC WAS ADVISED OF OUR ACTIONS WITHIN THE FIRST 30 SECS AND AGAIN AFTER THE WARNINGS STOPPED. AFTER THE SECOND NOTIFICATION WE WERE GIVEN A HDG AND ALT AT OUR DISCRETION FOR RADAR VECTORS TO AN ILS AT DULLES. WE EXECUTED THE ABOVE PROCS AS PER TRNING DICTATES. THE 3 COCKPIT CREW MEMBERS, IN RETROSPECT, COULD NOT JUSTIFY THE WARNINGS FOR THE REGIME OF FLT (I.E., 10000', NO TERRAIN PROBS, AT LEAST 5000' ABOVE ANY LCL MEA), BUT BEING TOTALLY IFR WE REACTED AS TRAINED AND CLBED OUT OF DANGER. THE CAPT'S RADIO ALTIMETER READ 700' WHEN THE WARNING SOUNDED AND WENT TO 500' BEFORE INCREASING. THIS MAY HAVE BEEN THE CAUSE OF THE PROB.

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.