Act large transport experiences localizer problems on approach to runway 4R at jfk.

Attributes
ACN	144321
Time
Date	199004
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : jfk
State Reference	NY
Altitude	msl bound lower : 500 msl bound upper : 2500
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tower : jfk artcc : zma
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : atp pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 15000
ASRS Report	144321
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	other anomaly other other spatial deviation
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	flight crew : overcame equipment problem flight crew : became reoriented flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other

Narrative:

While approaching jfk with autoplt coupled to ILS 4R on localizer on G/south at approximately 2500', localizer suddenly deviated to right. Autoplt was disconnected, and we commenced manual approach following localizer to 4R. Localizer fluctuated from right to left and then back to right. We broke out of overcast at 1000' and saw runway to the left and made uneventful landing. We had no warning flags on our avionics equipment. Suspect interference of some sort. After landing, heard other aircraft mention ILS interference on 4R on tower and ground control frequencys.

Original NASA ASRS Text

Title: ACT LGT EXPERIENCES LOCALIZER PROBLEMS ON APCH TO RWY 4R AT JFK.

Narrative: WHILE APCHING JFK WITH AUTOPLT COUPLED TO ILS 4R ON LOC ON G/S AT APPROX 2500', LOC SUDDENLY DEVIATED TO R. AUTOPLT WAS DISCONNECTED, AND WE COMMENCED MANUAL APCH FOLLOWING LOC TO 4R. LOC FLUCTUATED FROM R TO L AND THEN BACK TO R. WE BROKE OUT OF OVCST AT 1000' AND SAW RWY TO THE L AND MADE UNEVENTFUL LNDG. WE HAD NO WARNING FLAGS ON OUR AVIONICS EQUIP. SUSPECT INTERFERENCE OF SOME SORT. AFTER LNDG, HEARD OTHER ACFT MENTION ILS INTERFERENCE ON 4R ON TWR AND GND CTL FREQS.

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.