Light transport on vectors for final approach has GPWS alarm, responds.

Attributes
ACN	181793
Time
Date	199106
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : cha
State Reference	TN
Altitude	msl bound lower : 3500 msl bound upper : 4000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : cha tower : cle
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 35000 flight time type : 130
ASRS Report	181793
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 270 flight time total : 5000
ASRS Report	182232
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

While being vectored on a base leg for the ILS 20 at cha the GPWS issued a 'terrain' warning and 'pull up' command. We climbed from our assigned altitude of 3500' to 4000'. We notified approach of our climb passing through 3700-38000'. At 4000' the warning stopped. ATC advised us we were in a 3500' vectoring altitude sector, cleared us to 2500' with a 170 degree heading to intercept the 20 ILS and cleared us for the approach. This was our third night in a row making this approach into cha, and the second time in this aircraft. This was the first time we ever had a GPWS warning. I have heard of false warnings with this system, however, under the night-IMC conditions we had no choice but to climb.

Original NASA ASRS Text

Title: LTT ON VECTORS FOR FINAL APCH HAS GPWS ALARM, RESPONDS.

Narrative: WHILE BEING VECTORED ON A BASE LEG FOR THE ILS 20 AT CHA THE GPWS ISSUED A 'TERRAIN' WARNING AND 'PULL UP' COMMAND. WE CLBED FROM OUR ASSIGNED ALT OF 3500' TO 4000'. WE NOTIFIED APCH OF OUR CLB PASSING THROUGH 3700-38000'. AT 4000' THE WARNING STOPPED. ATC ADVISED US WE WERE IN A 3500' VECTORING ALT SECTOR, CLRED US TO 2500' WITH A 170 DEG HDG TO INTERCEPT THE 20 ILS AND CLRED US FOR THE APCH. THIS WAS OUR THIRD NIGHT IN A ROW MAKING THIS APCH INTO CHA, AND THE SEC TIME IN THIS ACFT. THIS WAS THE FIRST TIME WE EVER HAD A GPWS WARNING. I HAVE HEARD OF FALSE WARNINGS WITH THIS SYS, HOWEVER, UNDER THE NIGHT-IMC CONDITIONS WE HAD NO CHOICE BUT TO CLB.

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.