An EMB145 pilot reported that the aircraft autopilot does not track well on the localizer approach t...

Narrative:

Almost had to execute a missed approach while trying to track localizer 18L at cvg due to a well known anomaly on the embraer. The autopilot/localizer system in the airplane does not track well in some approaches around the country; another one is 18L in dfw. It is erratic and most of the time the autopilot has to be disconnected. Right before we had to execute a missed approach because we had full needle deflection we went visual. No far's were broken but not a good feeling. Everything else normal; final approach and landing with no major maneuvers. The point of the matter is that this should not happen; the systems in the airplane should work properly; the tower reported to us that the next two landing airplanes had no problems with the localizer; so the ground portion can be discounted. I spoke with another first officer and he said that it also happens at one of the localizer's in cmh. Corrective action: not sure; but at a minimum our air carrier should do some tests and figure out a way to fix the problem. In a long 13 hour duty day; with an approach to minimums in severe weather on the last leg of 5 leg day and at night; [it] could get ugly. Again; only localizer 18L in cvg; I've done several to cvg; 18C; 36C; 36L and no problem the embraer seems to handle those well; but not 18L.

Original NASA ASRS Text

Title: An EMB145 pilot reported that the aircraft autopilot does not track well on the LOC approach to CVG Runway 18L and at several other airports around the country. This anomaly could be an issue for a fatigued crew in poor weather.

Narrative: Almost had to execute a missed approach while trying to track LOC 18L at CVG due to a well known anomaly on the Embraer. The autopilot/localizer system in the airplane does not track well in some approaches around the country; another one is 18L in DFW. It is erratic and most of the time the autopilot has to be disconnected. Right before we had to execute a missed approach because we had full needle deflection we went visual. No FAR's were broken but not a good feeling. Everything else normal; final approach and landing with no major maneuvers. The point of the matter is that this should not happen; the systems in the airplane should work properly; the Tower reported to us that the next two landing airplanes had no problems with the LOC; so the ground portion can be discounted. I spoke with another First Officer and he said that it also happens at one of the LOC's in CMH. Corrective action: not sure; but at a minimum our air carrier should do some tests and figure out a way to fix the problem. In a long 13 hour duty day; with an approach to minimums in severe weather on the last leg of 5 leg day and at night; [it] could get ugly. Again; only LOC 18L in CVG; I've done several to CVG; 18C; 36C; 36L and no problem the Embraer seems to handle those well; but not 18L.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	929540
Time
Date	201101
Local Time Of Day	1201-1800
Place
Locale Reference	CVG.Airport
State Reference	KY
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	ILS/VOR
Person 1
Function	First Officer
Qualification	Flight Crew Commercial Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 210 Flight Crew Total 4000 Flight Crew Type 3000
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

An EMB145 pilot reported that the aircraft autopilot does not track well on the localizer approach to cvg runway 18L and at several other airports around the country. This anomaly could be an issue for a fatigued crew in poor weather.