Evasive action taken on ILS final to chicago for what turned out to be a false RA from the TCASII.

Attributes
ACN	485160
Time
Date	200009
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	msl bound lower : 1000 msl bound upper : 1500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : c90.tracon tower : bos.tower
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 22r other
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 16000 flight time type : 2500
ASRS Report	485160
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 30 flight time total : 2200 flight time type : 30
ASRS Report	485702
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : far non adherence : published procedure non adherence : company policies other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : became reoriented flight crew : returned to original clearance flight crew : took evasive action
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

False RA 1500 ft AGL, ILS runway 22R LOM. First officer flying. We followed RA aggressively, advised approach. He said he had no traffic near us. We turned off transponder (and TCASII), leveled off at 1000 ft AGL, reintercepted GS. Uneventful landing.

Original NASA ASRS Text

Title: EVASIVE ACTION TAKEN ON ILS FINAL TO CHICAGO FOR WHAT TURNED OUT TO BE A FALSE RA FROM THE TCASII.

Narrative: FALSE RA 1500 FT AGL, ILS RWY 22R LOM. FO FLYING. WE FOLLOWED RA AGGRESSIVELY, ADVISED APCH. HE SAID HE HAD NO TFC NEAR US. WE TURNED OFF XPONDER (AND TCASII), LEVELED OFF AT 1000 FT AGL, REINTERCEPTED GS. UNEVENTFUL LNDG.

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.