Narrative:

I was flying multiple ILS 36 practice approaches at ocf under the hood (with a safety pilot). My nav 1 is a garmin 430W. After the second approach I planned on flying the published missed for a hold. On the missed; the procedure calls for flying the ocf VORTAC R-355 to the holding fix. On missed; I engaged the autopilot which initiated a standard turn to the right to intercept what I then noticed to be the magenta course line which was well to the right of the heading called for in the procedure. The heading taken by the autopilot to the magenta line turned us approximately 35 degrees to the right of the published missed course; away from the runway; and in the general direction of the control tower. It was confusing at the time at a critical stage of my flight (climb-out on missed in simulated instrument conditions). However; there was no conflicting traffic; the tower controllers didn't mention it; and my safety pilot didn't comment on it. I became alarmed after the flight when I viewed my ground track on foreflight and saw that my heading on that botched missed approach took me generally towards the control tower. I simulated the approach on the 430W trainer at home to try to understand what happened. What I discovered; and since believe I have confirmed with other pilots; is that my garmin 430W navigation data base (which is current) erroneously renders the starting point of the missed approach course to the northeast side of the runway (the ocf VORTAC is located on the northwest side of the runway). The autopilot was attempting to intercept the erroneous missed approach course. The problem arose because the navigation data is incorrect and I spent time trying to figure out why things were happening like they were. I should have been flying the airplane where the approach plate directed me regardless of the GPS magenta line. Contributing to the problem was my bias towards believing my automation over myself; my concern that deviating from its guidance would endanger the flight; and the fact that the problem developed during a critical stage of the flight (climb-out in a high performance; complex airplane in simulated instrument conditions on missed approach).I'll definitely stick to the approach plates over my automation/GPS in the future (this situation has reformed my bias). Also; I'll ask my safety pilot (who is instrument rated) to follow along the approach procedures on these practice approaches more closely for deviations; we've evidently lapsed into a mere 'see and avoid' role for him.

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Original NASA ASRS Text

Title: A general aviation pilot reported that the GPS directed a missed approach course that did not agree with the published procedure for the ILS Runway 36 at OCF.

Narrative: I was flying multiple ILS 36 practice approaches at OCF under the hood (with a safety pilot). My Nav 1 is a Garmin 430W. After the second approach I planned on flying the published missed for a hold. On the missed; the procedure calls for flying the OCF VORTAC R-355 to the holding fix. On missed; I engaged the autopilot which initiated a standard turn to the right to intercept what I then noticed to be the magenta course line which was well to the right of the heading called for in the procedure. The heading taken by the autopilot to the magenta line turned us approximately 35 degrees to the right of the published missed course; away from the runway; and in the general direction of the control tower. It was confusing at the time at a critical stage of my flight (climb-out on missed in simulated instrument conditions). However; there was no conflicting traffic; the tower controllers didn't mention it; and my safety pilot didn't comment on it. I became alarmed after the flight when I viewed my ground track on Foreflight and saw that my heading on that botched missed approach took me generally towards the control tower. I simulated the approach on the 430W trainer at home to try to understand what happened. What I discovered; and since believe I have confirmed with other pilots; is that my Garmin 430W navigation data base (which is current) erroneously renders the starting point of the missed approach course to the NE side of the runway (the OCF VORTAC is located on the NW side of the runway). The autopilot was attempting to intercept the erroneous missed approach course. The problem arose because the navigation data is incorrect and I spent time trying to figure out why things were happening like they were. I should have been flying the airplane where the approach plate directed me regardless of the GPS magenta line. Contributing to the problem was my bias towards believing my automation over myself; my concern that deviating from its guidance would endanger the flight; and the fact that the problem developed during a critical stage of the flight (climb-out in a high performance; complex airplane in simulated instrument conditions on missed approach).I'll definitely stick to the approach plates over my automation/GPS in the future (this situation has reformed my bias). Also; I'll ask my safety pilot (who is instrument rated) to follow along the approach procedures on these practice approaches more closely for deviations; we've evidently lapsed into a mere 'see and avoid' role for him.

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.