Multiple runway operation simultaneous parallel instrument approachs. Aircraft deviation.

Attributes
ACN	328646
Time
Date	199602
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ifxd
State Reference	MO
Altitude	msl bound lower : 3300 msl bound upper : 3300
Aircraft 1
Controlling Facilities	tower : stl tower : hwd
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 4 controller radar : 18
ASRS Report	328646
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other spatial deviation
Independent Detector	other controllera
Resolutory Action	none taken : anomaly accepted
Consequence	faa : investigated
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

Stl has an lda/DME approach to runways 30L and 2L. At times on the lda/DME runway 30L approach, on about an 8-12 mi final, some aircraft drift left of the lda localizer into the ntz. When asked, the pilots say they are right on the localizer. My alignment was checked and was found to be within tolerances. Maintenance personnel now think it may be a radio frequency interference problem. This problem does not happen all of the time, only occasionally.

Original NASA ASRS Text

Title: MULTIPLE RWY OP SIMULTANEOUS PARALLEL INST APCHS. ACFT DEV.

Narrative: STL HAS AN LDA/DME APCH TO RWYS 30L AND 2L. AT TIMES ON THE LDA/DME RWY 30L APCH, ON ABOUT AN 8-12 MI FINAL, SOME ACFT DRIFT L OF THE LDA LOC INTO THE NTZ. WHEN ASKED, THE PLTS SAY THEY ARE RIGHT ON THE LOC. MY ALIGNMENT WAS CHKED AND WAS FOUND TO BE WITHIN TOLERANCES. MAINT PERSONNEL NOW THINK IT MAY BE A RADIO FREQ INTERFERENCE PROB. THIS PROB DOES NOT HAPPEN ALL OF THE TIME, ONLY OCCASIONALLY.

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.