Medium large transport flight crew on approach has TCASII RA. Evasive action.

Attributes
ACN	212985
Time
Date	199206
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ord
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 5200
Environment
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 150 flight time total : 6500 flight time type : 1000
ASRS Report	212985
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

During the approach segment of flight ord changed runway configns. We were assigned runway 22R ILS. During the radar vectors to the ILS 22R we observed a target on the TCASII screen and then a TA switched to RA mode. Target appeared to approach the 1 mi ring at which time we followed the RA commands to climb, which we went to 5200 at which time the ATC controller stated there was no traffic that close. We then went through wake turbulence which confirmed a critical intruder.

Original NASA ASRS Text

Title: MLG FLC ON APCH HAS TCASII RA. EVASIVE ACTION.

Narrative: DURING THE APCH SEGMENT OF FLT ORD CHANGED RWY CONFIGNS. WE WERE ASSIGNED RWY 22R ILS. DURING THE RADAR VECTORS TO THE ILS 22R WE OBSERVED A TARGET ON THE TCASII SCREEN AND THEN A TA SWITCHED TO RA MODE. TARGET APPEARED TO APCH THE 1 MI RING AT WHICH TIME WE FOLLOWED THE RA COMMANDS TO CLB, WHICH WE WENT TO 5200 AT WHICH TIME THE ATC CTLR STATED THERE WAS NO TFC THAT CLOSE. WE THEN WENT THROUGH WAKE TURB WHICH CONFIRMED A CRITICAL INTRUDER.

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.