Flight crew on ILS responds to TCASII RA.

Attributes
ACN	306880
Time
Date	199506
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 5500
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	306880
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew Other
Miss Distance	horizontal : 3000 vertical : 800
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On ILS to runway 04R ord at 5000 ft on GS received TA for aircraft off right front, 1900 ft TA became RA to climb and then climb climb now. Followed RA and climbed 400-500 ft above GS. Target aircraft passed at 3 O'clock, 1/2 mi and, 800 ft according to TCASII. At no time was the target in visual contact. ATC was advised and reported that the target was behind us. I suspect TCASII may have been mis-positioning the target.

Original NASA ASRS Text

Title: FLC ON ILS RESPONDS TO TCASII RA.

Narrative: ON ILS TO RWY 04R ORD AT 5000 FT ON GS RECEIVED TA FOR ACFT OFF R FRONT, 1900 FT TA BECAME RA TO CLB AND THEN CLB CLB NOW. FOLLOWED RA AND CLBED 400-500 FT ABOVE GS. TARGET ACFT PASSED AT 3 O'CLOCK, 1/2 MI AND, 800 FT ACCORDING TO TCASII. AT NO TIME WAS THE TARGET IN VISUAL CONTACT. ATC WAS ADVISED AND RPTED THAT THE TARGET WAS BEHIND US. I SUSPECT TCASII MAY HAVE BEEN MIS-POSITIONING THE TARGET.

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.