B727 crew received a GPS terrain warning to pull up.

Attributes
ACN	495711
Time
Date	200012
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : cpr.airport
State Reference	WY
Altitude	msl bound lower : 9500 msl bound upper : 11000
Environment
Flight Conditions	IMC
Weather Elements	Snow
Light	Night
Aircraft 1
Controlling Facilities	tracon : cpr.tracon
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 75 flight time total : 7000 flight time type : 600
ASRS Report	495711
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	aircraft equipment : gpws
Resolutory Action	flight crew : took precautionary avoidance action
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flight departed holding ddy VOR and vectored for ILS runway 3 cpr. Flight descended to assigned altitude of 9500 ft. Level at 9500 ft, downwind runway 3, gpwas activated with 'whoop, whoop, pull up, terrain, ter....' the second 'terrain' stopped short as the captain initiated an immediate climb to 11000 ft. The first officer informed ATC of the emergency escape maneuver due to gpwas activation. ATC asked what a GPS (sic) was. Captain explained to ATC that a terrain avoidance maneuver had been executed due to a cockpit alarm. ATC responded that our altitude had been at the minimum safe vectoring altitude. ATC then asked if we could descend and continue the approach.

Original NASA ASRS Text

Title: B727 CREW RECEIVED A GPS TERRAIN WARNING TO PULL UP.

Narrative: FLT DEPARTED HOLDING DDY VOR AND VECTORED FOR ILS RWY 3 CPR. FLT DSNDED TO ASSIGNED ALT OF 9500 FT. LEVEL AT 9500 FT, DOWNWIND RWY 3, GPWAS ACTIVATED WITH 'WHOOP, WHOOP, PULL UP, TERRAIN, TER....' THE SECOND 'TERRAIN' STOPPED SHORT AS THE CAPT INITIATED AN IMMEDIATE CLB TO 11000 FT. THE FO INFORMED ATC OF THE EMER ESCAPE MANEUVER DUE TO GPWAS ACTIVATION. ATC ASKED WHAT A GPS (SIC) WAS. CAPT EXPLAINED TO ATC THAT A TERRAIN AVOIDANCE MANEUVER HAD BEEN EXECUTED DUE TO A COCKPIT ALARM. ATC RESPONDED THAT OUR ALT HAD BEEN AT THE MINIMUM SAFE VECTORING ALT. ATC THEN ASKED IF WE COULD DSND AND CONTINUE THE APCH.

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.