An air carrier mdt pilot complains about the ibul localizer.

Attributes
ACN	277058
Time
Date	199407
Day	Thu
Place
Locale Reference	airport : mia
State Reference	FL
Altitude	agl bound lower : 50 agl bound upper : 200
Aircraft 1
Controlling Facilities	tower : mia
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : ibul Other Other
Flight Phase	descent : approach landing other
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 8000
ASRS Report	277058
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

I have noted a NAVAID anomaly with respect to the localizer runway 9R transmitter. I always tune in the localizer with any approach -- even VFR. This occurs every time, irrespective of the D-8 I fly. At decision ht, 200 AGL, the expanded localizer indicator begins (full scale) to fluctuate erratically. This continues to approximately 50 ft AGL. (Also known as 'pac man' needle). In dense fog, we utilize the expanded localizer for visual assist/backup down to the runway surface FAA needs to investigate this anomaly.

Original NASA ASRS Text

Title: AN ACR MDT PLT COMPLAINS ABOUT THE IBUL LOC.

Narrative: I HAVE NOTED A NAVAID ANOMALY WITH RESPECT TO THE LOC RWY 9R XMITTER. I ALWAYS TUNE IN THE LOC WITH ANY APCH -- EVEN VFR. THIS OCCURS EVERY TIME, IRRESPECTIVE OF THE D-8 I FLY. AT DECISION HT, 200 AGL, THE EXPANDED LOC INDICATOR BEGINS (FULL SCALE) TO FLUCTUATE ERRATICALLY. THIS CONTINUES TO APPROX 50 FT AGL. (ALSO KNOWN AS 'PAC MAN' NEEDLE). IN DENSE FOG, WE UTILIZE THE EXPANDED LOC FOR VISUAL ASSIST/BACKUP DOWN TO THE RWY SURFACE FAA NEEDS TO INVESTIGATE THIS ANOMALY.

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.