Emb captain reported tower advised of a track deviation on ILS approach to iah.

Attributes
ACN	1744133
Time
Date	202005
Local Time Of Day	1801-2400
Place
Locale Reference	IAH.Airport
State Reference	TX
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Embraer Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	Navigational Equipment and Processing
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Wake Vortex Encounter Inflight Event / Encounter Weather / Turbulence

Narrative:

I was flying pilot on ILS 8R at iah. Localizer was very squirrelly. Autopilot was chasing it; so I disconnected and hand flew probably around reign. Localizer was very sensitive and fluctuating back and forth 1/4 to 1/2 dot. Kept it relatively centered. Was barely deflected; less than 1/4 dot and tower override says we are south of localizer; turn left immediately and re-intercept. According to CDI we were just slightly right; almost touching centered. I made a correction to the north and changed to magenta needles to follow until outside of OM. While on magenta needles; we encountered wake turbulence. Aircraft in front of us was about 6 miles ahead. We had aircraft to the south on parallel below us. Went back to green needles outside of OM. Light rain but we got visual of the runway. Localizer seemed to be slightly off; and sensitive. I queried if anyone else had issues with localizer; tower said no; and that we were back and forth across course for most of the arrival. I wrote it up when we arrived at the gate. Threat of possible inaccurate CDI/localizer. Hand flying. Being south of localizer during parallel approaches is undesirable. Wake turbulence possibly because of south of course. Use magenta needles for longer on approach. Turn autopilot back on.

Original NASA ASRS Text

Title: EMB Captain reported Tower advised of a track deviation on ILS approach to IAH.

Narrative: I was flying pilot on ILS 8R at IAH. LOC was very squirrelly. Autopilot was chasing it; so I disconnected and hand flew probably around REIGN. LOC was very sensitive and fluctuating back and forth 1/4 to 1/2 dot. Kept it relatively centered. Was barely deflected; less than 1/4 dot and Tower override says we are south of localizer; turn left immediately and re-intercept. According to CDI we were just slightly right; almost touching centered. I made a correction to the north and changed to magenta needles to follow until outside of OM. While on magenta needles; we encountered wake turbulence. Aircraft in front of us was about 6 miles ahead. We had aircraft to the south on parallel below us. Went back to green needles outside of OM. Light rain but we got visual of the runway. Localizer seemed to be slightly off; and sensitive. I queried if anyone else had issues with localizer; Tower said no; and that we were back and forth across course for most of the arrival. I wrote it up when we arrived at the gate. Threat of possible inaccurate CDI/localizer. Hand flying. Being south of localizer during parallel approaches is undesirable. Wake turbulence possibly because of south of course. Use magenta needles for longer on approach. Turn autopilot back on.

Data retrieved from NASA's ASRS site 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.