While being vectored for an approach, light transport received GPWS.

Attributes
ACN	257548
Time
Date	199311
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : tri
State Reference	TN
Altitude	msl bound lower : 4300 msl bound upper : 4300
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : tri
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other descent : approach
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 : 170 flight time total : 6200 flight time type : 600
ASRS Report	257548
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Aircraft was level at 4300 ft MSL approximately 20 KTS IMC in rain at night. Receiving radar vectors for an ILS to runway 23 at tri city airport, tn. Was about 360 degrees and 10-12 mi from airport. From GPWS got a 'whoop, whoop, pull up,' then several 'terrain, terrain' warnings. We initiated a climb (climbed to 5300 ft) and told approach. They verified we had the correct altimeter setting, which we did. After the warnings stopped we were cleared once again to 4300 ft. Note that several other air crews flying the light transport have had similar experiences at tri. Perhaps the minimum safe vector altitude should be reevaluated for this airport. Or it might be a problem with the parameters of our GPWS.

Original NASA ASRS Text

Title: WHILE BEING VECTORED FOR AN APCH, LTT RECEIVED GPWS.

Narrative: ACFT WAS LEVEL AT 4300 FT MSL APPROX 20 KTS IMC IN RAIN AT NIGHT. RECEIVING RADAR VECTORS FOR AN ILS TO RWY 23 AT TRI CITY ARPT, TN. WAS ABOUT 360 DEGS AND 10-12 MI FROM ARPT. FROM GPWS GOT A 'WHOOP, WHOOP, PULL UP,' THEN SEVERAL 'TERRAIN, TERRAIN' WARNINGS. WE INITIATED A CLB (CLBED TO 5300 FT) AND TOLD APCH. THEY VERIFIED WE HAD THE CORRECT ALTIMETER SETTING, WHICH WE DID. AFTER THE WARNINGS STOPPED WE WERE CLRED ONCE AGAIN TO 4300 FT. NOTE THAT SEVERAL OTHER AIR CREWS FLYING THE LTT HAVE HAD SIMILAR EXPERIENCES AT TRI. PERHAPS THE MINIMUM SAFE VECTOR ALT SHOULD BE REEVALUATED FOR THIS ARPT. OR IT MIGHT BE A PROB WITH THE PARAMETERS OF OUR GPWS.

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.