Narrative:

I was instructed by ATC to maintain 3400 ft on vectors to final ILS 28R oak. I then intercepted localizer and was cleared for the approach. I continued my intercept; as localizer CDI was active but not yet fully intercepted. I turned to an estimated heading of 240. Upon noticing that I had an excess altitude of nearly 500 ft; I needed to increase my descent. I notified ATC of my intention to perform a left hand 360-degree turn and re-intercept localizer. I was in VMC; and had simply needed a reminder that upon receiving my IFR clearance; the responsibility of terrain and traffic avoidance became shared by ATC and myself. Approximately 90 degrees into the turn and after a response from ATC; I corrected the action and turned back on the proper heading by which time a possible pilot deviation had been noted. Cause for the excess altitude was a pilot lack of situational awareness. I expected to intercept localizer at grove; but instead was approaching urzaf. Factors affecting the quality of my performance under IFR was a direct result of unclear distinction as to when I fell under IFR regulations. In practice approaches in VFR conditions; when ATC was not responsible for aircraft separation; there was more flexibility in procedures. I called norcal approach when I completed my flight; and have been actively cooperating with any and all requests thereafter.

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Original NASA ASRS Text

Title: C172 pilot and TRACON Controller reported confusion on the part of the pilot about following ATC instructions under an IFR clearance.

Narrative: I was instructed by ATC to maintain 3400 ft on vectors to final ILS 28R OAK. I then intercepted localizer and was cleared for the approach. I continued my intercept; as localizer CDI was active but not yet fully intercepted. I turned to an estimated heading of 240. Upon noticing that I had an excess altitude of nearly 500 ft; I needed to increase my descent. I notified ATC of my intention to perform a left hand 360-degree turn and re-intercept localizer. I was in VMC; and had simply needed a reminder that upon receiving my IFR clearance; the responsibility of terrain and traffic avoidance became shared by ATC and myself. Approximately 90 degrees into the turn and after a response from ATC; I corrected the action and turned back on the proper heading by which time a possible pilot deviation had been noted. Cause for the excess altitude was a pilot lack of situational awareness. I expected to intercept localizer at GROVE; but instead was approaching URZAF. Factors affecting the quality of my performance under IFR was a direct result of unclear distinction as to when I fell under IFR regulations. In practice approaches in VFR conditions; when ATC was not responsible for aircraft separation; there was more flexibility in procedures. I called Norcal Approach when I completed my flight; and have been actively cooperating with any and all requests thereafter.

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.