Narrative:

I was flying on instrument plan and was vectored and then cleared for the RNAV runway 19 approach. On approach; my number 1 GPS failed and I called approach telling them it had failed and they gave me a heading and steer while I figured out what to do next. ATIS was reporting 800 ovc so I decided to try the VOR-a. I set the number 1 navigation up and was cleared for the approach. I started the approach and at minimums of 1;360 ft (538 above field); I caught a small glimpse of field but weather was lower than reported. Was told by someone on ground they thought it was 300 ovc. I reported missed and at that time; my number 1 GPS came back but my indicator 'froze.' being distracted; I busted the climb. Approach then gave me vectors to indianapolis for the ILS 5L approach. In vectoring for approach; I put autopilot on a heading bug and altitude hold to give me time to pull out approach plate and set up approach while flying IMC. However; the number 1 GPS kept coming back and then going out and each time; it kicked off the autopilot leading me to deviate from heading/altitude. I finally got the ILS dialed in and approach sent me past the localizer and then turned me back to join the approach. After clearing me on approach; I started down. However; the number 1 GPS in the unit; whenever it came back or went off caused the indicator to go back to center for a few seconds before showing the 'true indication' of the localizer/glideslope. After trying to correct a couple of times; I finally called missed and approach was helpful in looking for some better weather. They asked if I could make it to lafayette; indiana and I replied I could. Approach gave me vectors and altitudes. Meanwhile; the autopilot kept getting kicked off and as I was trying to determine if the problem was only the number 1 or both the number 1 and number 2 navs; I was distracted and deviated my altitude (flying higher than cleared). I finally was able to determine that the problem was exclusive to the number 1 navigation/GPS and switched to the number 2 navigation and set it up for the ILS. After setting up the number 2 and having a steady signal/guidance; I then turned my attention to flying the aircraft and made a good ILS approach with needles centered on glideslope. I landed with 33 minutes fuel left in the tanks. Tower asked me to call one of the controllers at indianapolis who asked what problem was and I explained that my number 1 GPS kept interfering with the navigation portion of the unit and freezing the indicator for a few seconds.

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Original NASA ASRS Text

Title: Lancair pilot reports three missed approaches and two diversions due to NAV/GPS malfunctions; landing with 33 minutes of fuel remaining.

Narrative: I was flying on instrument plan and was vectored and then cleared for the RNAV RWY 19 approach. On approach; my Number 1 GPS failed and I called Approach telling them it had failed and they gave me a heading and steer while I figured out what to do next. ATIS was reporting 800 OVC so I decided to try the VOR-A. I set the Number 1 NAV up and was cleared for the approach. I started the approach and at minimums of 1;360 FT (538 above field); I caught a small glimpse of field but weather was lower than reported. Was told by someone on ground they thought it was 300 OVC. I reported missed and at that time; my Number 1 GPS came back but my indicator 'froze.' Being distracted; I busted the climb. Approach then gave me vectors to Indianapolis for the ILS 5L approach. In vectoring for approach; I put autopilot on a heading bug and altitude hold to give me time to pull out approach plate and set up approach while flying IMC. However; the Number 1 GPS kept coming back and then going out and each time; it kicked off the autopilot leading me to deviate from heading/altitude. I finally got the ILS dialed in and Approach sent me past the localizer and then turned me back to join the approach. After clearing me on approach; I started down. However; the Number 1 GPS in the unit; whenever it came back or went off caused the indicator to go back to center for a few seconds before showing the 'true indication' of the localizer/glideslope. After trying to correct a couple of times; I finally called missed and approach was helpful in looking for some better weather. They asked if I could make it to Lafayette; Indiana and I replied I could. Approach gave me vectors and altitudes. Meanwhile; the autopilot kept getting kicked off and as I was trying to determine if the problem was only the Number 1 or both the Number 1 and Number 2 NAVs; I was distracted and deviated my altitude (flying higher than cleared). I finally was able to determine that the problem was exclusive to the Number 1 NAV/GPS and switched to the Number 2 NAV and set it up for the ILS. After setting up the Number 2 and having a steady signal/guidance; I then turned my attention to flying the aircraft and made a good ILS approach with needles centered on glideslope. I landed with 33 minutes fuel left in the tanks. Tower asked me to call one of the controllers at Indianapolis who asked what problem was and I explained that my Number 1 GPS kept interfering with the NAV portion of the unit and freezing the indicator for a few seconds.

Data retrieved from NASA's ASRS site as of July 2013 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.