Air carrier flight crew experiences false TCASII warning.

Attributes
ACN	264536
Time
Date	199402
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mdw
State Reference	IL
Altitude	msl bound lower : 2700 msl bound upper : 3000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord artcc : zob
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 150 flight time total : 15000 flight time type : 6000
ASRS Report	264536
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

TCASII gave a false RA to descend. No traffic call just 'descend, descend' with red traffic 1/2 mi 12 O'clock, plus 200 ft. Traffic suddenly appeared with RA. We descended 300 ft and traffic and RA disappeared. Advised ATC and they showed no traffic.

Original NASA ASRS Text

Title: ACR FLC EXPERIENCES FALSE TCASII WARNING.

Narrative: TCASII GAVE A FALSE RA TO DSND. NO TFC CALL JUST 'DSND, DSND' WITH RED TFC 1/2 MI 12 O'CLOCK, PLUS 200 FT. TFC SUDDENLY APPEARED WITH RA. WE DSNDED 300 FT AND TFC AND RA DISAPPEARED. ADVISED ATC AND THEY SHOWED NO TFC.

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.