MD80 crew got a GPWS 'terrain' warning at 8000 ft in IMC conditions, in the rain, arriving at ord.

Attributes
ACN	547019
Time
Date	200205
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	msl single value : 8000
Environment
Flight Conditions	IMC
Weather Elements	Rain
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : c90.tracon tower : eug.tower
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	approach : traffic pattern arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	547019
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	547015
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather inflight encounter other
Independent Detector	aircraft equipment : gpws other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action flight crew : exited adverse environment flight crew : overrode automation flight crew : returned to assigned airspace other
Consequence	other other
Supplementary
Problem Areas	Company FAA Weather Aircraft
Primary Problem	Aircraft

Narrative:

Terrain alert. First officer flying on downwind to runway 22R ord at 8000 ft in IMC and light rain. We got a 'terrain, terrain' alert. We climbed to 8800 ft and told approach, which said there was nothing there. Alert stopped and we returned to altitude. We did not exceed go around power. Supplemental information from acn 547015: in moderate rainstorm, first officer disconnected autothrottles and autoplt, added power and climbed to 9000 ft. Approach controller was advised. Aircraft flown to uneventful landing and maintenance notified of false warning.

Original NASA ASRS Text

Title: MD80 CREW GOT A GPWS 'TERRAIN' WARNING AT 8000 FT IN IMC CONDITIONS, IN THE RAIN, ARRIVING AT ORD.

Narrative: TERRAIN ALERT. FO FLYING ON DOWNWIND TO RWY 22R ORD AT 8000 FT IN IMC AND LIGHT RAIN. WE GOT A 'TERRAIN, TERRAIN' ALERT. WE CLBED TO 8800 FT AND TOLD APCH, WHICH SAID THERE WAS NOTHING THERE. ALERT STOPPED AND WE RETURNED TO ALT. WE DID NOT EXCEED GAR PWR. SUPPLEMENTAL INFO FROM ACN 547015: IN MODERATE RAINSTORM, FO DISCONNECTED AUTOTHROTTLES AND AUTOPLT, ADDED PWR AND CLBED TO 9000 FT. APCH CTLR WAS ADVISED. ACFT FLOWN TO UNEVENTFUL LNDG AND MAINT NOTIFIED OF FALSE WARNING.

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.