F100 crew had a GPWS terrain warning in mdt class D airspace.

Attributes
ACN	479063
Time
Date	200007
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : mdt.airport
State Reference	PA
Altitude	msl bound lower : 5000 msl bound upper : 9000
Environment
Flight Conditions	IMC
Weather Elements	Rain Turbulence
Light	Night
Aircraft 1
Controlling Facilities	tracon : mdt.tracon tower : clt.tower
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
ASRS Report	479063
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment : gpws other flight crewa other flight crewb
Resolutory Action	controller : provided flight assist controller : issued new clearance flight crew : took evasive action
Consequence	other
Supplementary
Problem Areas	Aircraft Weather
Primary Problem	Aircraft

Narrative:

Altitude deviation due to GPWS alert. During descent into mdt in an F100, radar was on with first officer in terrain mode and captain in WX mode. During descent from 8000 ft to 4000 ft MSL, we entered moderate rain and turbulence. It was night in IMC. Passing about 5000 ft, the GPWS alert for 'terrain, terrain, pull up' went off. The captain immediately applied the appropriate procedure with the climb. I called approach and told them we were climbing for a terrain alert we were given 7000 ft to maintain. I asked for 8000 ft since we were passing 7000 ft with the warning going off again. We were given 8000 ft to maintain as we were passing 8000 ft. We leveled off at 9000 ft with all alerts extinguished. Approach control did not seem to have a problem with our climb. We requested another descent and descended without incident. The GPWS went off at approximately 5000 ft. The grid mora was 5000 ft.

Original NASA ASRS Text

Title: F100 CREW HAD A GPWS TERRAIN WARNING IN MDT CLASS D AIRSPACE.

Narrative: ALTDEV DUE TO GPWS ALERT. DURING DSCNT INTO MDT IN AN F100, RADAR WAS ON WITH FO IN TERRAIN MODE AND CAPT IN WX MODE. DURING DSCNT FROM 8000 FT TO 4000 FT MSL, WE ENTERED MODERATE RAIN AND TURB. IT WAS NIGHT IN IMC. PASSING ABOUT 5000 FT, THE GPWS ALERT FOR 'TERRAIN, TERRAIN, PULL UP' WENT OFF. THE CAPT IMMEDIATELY APPLIED THE APPROPRIATE PROC WITH THE CLB. I CALLED APCH AND TOLD THEM WE WERE CLBING FOR A TERRAIN ALERT WE WERE GIVEN 7000 FT TO MAINTAIN. I ASKED FOR 8000 FT SINCE WE WERE PASSING 7000 FT WITH THE WARNING GOING OFF AGAIN. WE WERE GIVEN 8000 FT TO MAINTAIN AS WE WERE PASSING 8000 FT. WE LEVELED OFF AT 9000 FT WITH ALL ALERTS EXTINGUISHED. APCH CTL DID NOT SEEM TO HAVE A PROB WITH OUR CLB. WE REQUESTED ANOTHER DSCNT AND DSNDED WITHOUT INCIDENT. THE GPWS WENT OFF AT APPROX 5000 FT. THE GRID MORA WAS 5000 FT.

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.