Narrative:

Initially completed a flight to ZZZ; setup garmin 650 navigation for an approach to ZZZ runway 15. Contacted the tower at ZZZ clear to land. Garmin 650 appeared to function normally. Completed two local flights and checked weather for return. Weather was IFR... Filed flight plan. Contacted ZZZ ground for clearance. Taxied to runway 15 to departure. Setup garmin 650 for direct to destination. Contacted approach... Everything normal. Climbed to 3000. Received headings from ATC. ATC indicated to turn left to intercept the inbound course. That is when I realized the GPS or I was not functioning properly. Advised ATC immediately. Radar vectored around to try again. Recycle GPS and reset it to [dkb] GPS runway xx. Tried again. In the meantime; I become extremely rattled by the GPS issue. Lost altitude and heading. Recovered back to 3000 and ATC heading. ATC was extremely professional and worked with me until we both realized I was unable to correct the GPS issue... We agreed to change the approach to the ILS. Thereby not relying on the GPS at all. ATC gave me radar vectors to the ILS approach course. Which I was able to intercept the localizer and follow the glide slope to circle to land ... Closed flight plan. The overall issue with the GPS is very concerning... I plan to go back out with a cfii this week to review the issue by repeating in VFR conditions the approach and figure out what I may have done wrong or if the GPS unit had a problem and get it fixed!!! The bottom line will be to get more training from a cfii and ensure this issue is never repeated. I have made many flights and approaches with the garmin 650 and am current IFR in the previous 6 months. In fact; in practice I have made at least 12 GPS approaches simulated in the past 6 months or so. With a cfii and/or check pilot.

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Original NASA ASRS Text

Title: Pilot reported experiencing erratic GPS input and display while in IMC flight conditions.

Narrative: Initially completed a flight to ZZZ; setup Garmin 650 NAV for an approach to ZZZ Runway 15. Contacted the tower at ZZZ clear to land. Garmin 650 appeared to function normally. Completed two local flights and checked weather for return. Weather was IFR... filed flight plan. Contacted ZZZ Ground for clearance. Taxied to Runway 15 to departure. Setup Garmin 650 for direct to destination. Contacted Approach... Everything normal. Climbed to 3000. Received headings from ATC. ATC indicated to turn left to intercept the inbound course. That is when I realized the GPS or I was not functioning properly. Advised ATC immediately. Radar vectored around to try again. Recycle GPS and reset it to [DKB] GPS Runway XX. Tried again. In the meantime; I become extremely rattled by the GPS issue. Lost altitude and heading. Recovered back to 3000 and ATC heading. ATC was extremely professional and worked with me until we both realized I was unable to correct the GPS issue... we agreed to change the approach to the ILS. Thereby not relying on the GPS at all. ATC gave me radar vectors to the ILS approach course. Which I was able to intercept the localizer and follow the glide slope to circle to land ... closed flight plan. The overall issue with the GPS is very concerning... I plan to go back out with a CFII this week to review the issue by repeating in VFR conditions the approach and figure out what I may have done wrong or if the GPS unit had a problem and get it fixed!!! The bottom line will be to get more training from a CFII and ensure this issue is never repeated. I have made many flights and approaches with the Garmin 650 and am current IFR in the previous 6 months. In fact; in practice I have made at least 12 GPS approaches simulated in the past 6 months or so. With a CFII and/or Check Pilot.

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.