Narrative:

While conducting the sts VOR DME runway 14 approach; and while executing the published procedure turn; our ground track crossed over onto the non-protected side; east of the final approach course. The cause for the deviation was the result of an object (an ipad) being placed on the glare shield which caused the magnetic compass to show an erroneous indication; and thus our directional gyro was not correctly referenced. While tracking outbound on the 326 radial; the CDI was centered and we tracked the course properly; however; once we began the procedure turn and turned left to what we believed to be was a heading of 281 as published; we were in fact on a heading closer to 300 degrees. We flew for 1 minute and then turned to the right to join the final approach course. During our turn back to course; the center controller advised us that we were east of the final approach course and that we needed to ascend immediately because we were below his MVA for the area we were in. Being that we were in VMC; I immediately canceled our IFR; and we continued VFR into sts to land. After landing we determined that the ipad being placed on the glare shield was the cause for the disturbance to the magnetic compass. As a further note; the ipad was not turned on; in fact the battery was fully discharged. The ipad is getting a lot of praise from the aviation industry; as it is certainly a useful tool for pilots; however; I would recommend that some literature be published to warn pilots of the potential danger it could present in the form of interference with other instruments if not mounted or placed in area known not to cause interference.

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Original NASA ASRS Text

Title: C172 instructor pilot reports course deviation during VOR approach to STS caused by improperly set directional gyro. An iPad placed on the glareshield caused the wet compass to read inaccurately and the gyro was not set correctly. The iPad was not on at the time and in fact the battery was completely discharged.

Narrative: While conducting the STS VOR DME Runway 14 approach; and while executing the published procedure turn; our ground track crossed over onto the non-protected side; east of the final approach course. The cause for the deviation was the result of an object (an iPad) being placed on the glare shield which caused the magnetic compass to show an erroneous indication; and thus our directional gyro was not correctly referenced. While tracking outbound on the 326 radial; the CDI was centered and we tracked the course properly; however; once we began the procedure turn and turned left to what we believed to be was a heading of 281 as published; we were in fact on a heading closer to 300 degrees. We flew for 1 minute and then turned to the right to join the final approach course. During our turn back to course; the Center Controller advised us that we were east of the final approach course and that we needed to ascend immediately because we were below his MVA for the area we were in. Being that we were in VMC; I immediately canceled our IFR; and we continued VFR into STS to land. After landing we determined that the iPad being placed on the glare shield was the cause for the disturbance to the magnetic compass. As a further note; the iPad was not turned on; in fact the battery was fully discharged. The iPad is getting a lot of praise from the aviation industry; as it is certainly a useful tool for pilots; however; I would recommend that some literature be published to warn pilots of the potential danger it could present in the form of interference with other instruments if not mounted or placed in area known not to cause interference.

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.