An air carrier captain reported that a TCASII RA occurred while on final for ILS runway 4R at ewr.

Attributes
ACN	486490
Time
Date	200009
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ewr.airport
State Reference	NJ
Altitude	msl bound lower : 2000 msl bound upper : 3000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90.tracon tower : myf.tower
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 4r other
Flight Phase	descent : approach
Route In Use	approach : instrument precision arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : n90.tracon
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 230 flight time total : 17000 flight time type : 1100
ASRS Report	486490
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Events
Anomaly	inflight encounter other other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Vectored to ILS final runway 4R ewr. While on intercept heading (at 300 ft MSL), given 'maintain 2000 ft until established, cleared ILS runway 4R.' while on final and descending to 2000 ft, traffic appeared ahead on TCASII screen at 2000 ft (slow moving or stationary) at approximately 3 mi. While attempting to ask tower about it, we got an RA from TCASII. Executed RA maneuver. No further problem. Called tower on phone. They said it as unknown traffic, and we never lost separation from known IFR traffic. Due to layered clouds, we never acquired traffic visually.

Original NASA ASRS Text

Title: AN ACR CAPT RPTED THAT A TCASII RA OCCURRED WHILE ON FINAL FOR ILS RWY 4R AT EWR.

Narrative: VECTORED TO ILS FINAL RWY 4R EWR. WHILE ON INTERCEPT HDG (AT 300 FT MSL), GIVEN 'MAINTAIN 2000 FT UNTIL ESTABLISHED, CLRED ILS RWY 4R.' WHILE ON FINAL AND DSNDING TO 2000 FT, TFC APPEARED AHEAD ON TCASII SCREEN AT 2000 FT (SLOW MOVING OR STATIONARY) AT APPROX 3 MI. WHILE ATTEMPTING TO ASK TWR ABOUT IT, WE GOT AN RA FROM TCASII. EXECUTED RA MANEUVER. NO FURTHER PROB. CALLED TWR ON PHONE. THEY SAID IT AS UNKNOWN TFC, AND WE NEVER LOST SEPARATION FROM KNOWN IFR TFC. DUE TO LAYERED CLOUDS, WE NEVER ACQUIRED TFC VISUALLY.

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.