Narrative:

On being vectored for the ILS runway 20 at baf by bradley approach control on a practice approach in IMC at my assigned altitude of 3000 ft, I received a navigation flag on the localizer/GS readout instrument. I informed bradley of the flag, and asked to have time to figure out the problem. Bradley told me to remain at 3000 ft and gave me a heading of 110 degrees. For the next 5 mins I tried to figure out why I was getting flags on both navigation and GS. I was unable to determine the source of the difficulty, so I switched to the #2 navigation system and requested the VOR approach to baf runway 20. Bradley vectored me around, and then cleared me for the approach, which I executed and landed. During the time I was investigating the problem, both my heading and altitude varied considerably. I was more than 300 ft above and below the assigned 3000 ft altitude, and my heading varied substantially. I was in solid IMC the whole time. While the controller was patient and helpful, and I eventually (if somewhat erratically) worked my way back to the airport using the VOR approach, I am reporting the unintentional deviation from ATC assignments. I realize now that I should have xferred sooner to the navigation #2 system and concentrated more on stabilizing the approach. Although I am IFR current, I have scheduled time with an instructor to improve my proficiency in actual IMC.

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Original NASA ASRS Text

Title: C172 PRACTICING IFR APCHS INTO BAF VARIES FROM ATC ASSIGNED ALT AND HEADING.

Narrative: ON BEING VECTORED FOR THE ILS RWY 20 AT BAF BY BRADLEY APCH CTL ON A PRACTICE APCH IN IMC AT MY ASSIGNED ALT OF 3000 FT, I RECEIVED A NAV FLAG ON THE LOC/GS READOUT INST. I INFORMED BRADLEY OF THE FLAG, AND ASKED TO HAVE TIME TO FIGURE OUT THE PROB. BRADLEY TOLD ME TO REMAIN AT 3000 FT AND GAVE ME A HEADING OF 110 DEGS. FOR THE NEXT 5 MINS I TRIED TO FIGURE OUT WHY I WAS GETTING FLAGS ON BOTH NAV AND GS. I WAS UNABLE TO DETERMINE THE SOURCE OF THE DIFFICULTY, SO I SWITCHED TO THE #2 NAV SYS AND REQUESTED THE VOR APCH TO BAF RWY 20. BRADLEY VECTORED ME AROUND, AND THEN CLRED ME FOR THE APCH, WHICH I EXECUTED AND LANDED. DURING THE TIME I WAS INVESTIGATING THE PROB, BOTH MY HEADING AND ALT VARIED CONSIDERABLY. I WAS MORE THAN 300 FT ABOVE AND BELOW THE ASSIGNED 3000 FT ALT, AND MY HEADING VARIED SUBSTANTIALLY. I WAS IN SOLID IMC THE WHOLE TIME. WHILE THE CTLR WAS PATIENT AND HELPFUL, AND I EVENTUALLY (IF SOMEWHAT ERRATICALLY) WORKED MY WAY BACK TO THE ARPT USING THE VOR APCH, I AM RPTING THE UNINTENTIONAL DEV FROM ATC ASSIGNMENTS. I REALIZE NOW THAT I SHOULD HAVE XFERRED SOONER TO THE NAV #2 SYS AND CONCENTRATED MORE ON STABILIZING THE APCH. ALTHOUGH I AM IFR CURRENT, I HAVE SCHEDULED TIME WITH AN INSTRUCTOR TO IMPROVE MY PROFICIENCY IN ACTUAL IMC.

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.