Narrative:

I departed and had to switch over to symbol #2 generator to get navigation system to track to GPS route. Was on IFR vectors to localizer when I realized none of my IFR approach options were working. So we were in VFR conditions and I saw the airport and canceled IFR. Started VFR approach and contacted tower. Was told to cancel all restrictions and cleared to land. Knowing the area very well; I stayed in visual contact with airport and landed. After landing called maintenance and told them of the lock up I had on the navigation system. After the systems were shut down I ordered gpu hook up and turned avionics back on and everything was working. I have never seen this happen before I thought I had symbol generator #1 problem and when we switched to #2 it all worked and we continued our flight. We left for two leg flight the next day everything worked. I have ordered another computer system that operates most all autopilot and navigation systems. Whatever locked up the system somehow corrected its condition when power was removed after shut down. I had a lot of VFR options for landing at other airports; but having a visual contact with my destination made the most sense. Having back up systems are great but having the kind of lock up in the navigation system changes the landing options to VFR only. Knowing the system the way I do; some sort of electronic lock up occurred and may never happen again but replacing the main computer system should prevent it from ever happening again.

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Original NASA ASRS Text

Title: A CE560 Symbol Generator #1 malfunctioned in flight; disabling navigation systems. After landing all systems returned to normal after they were shutdown and restarted.

Narrative: I departed and had to switch over to symbol #2 generator to get navigation system to track to GPS route. Was on IFR vectors to localizer when I realized none of my IFR approach options were working. So we were in VFR conditions and I saw the airport and canceled IFR. Started VFR approach and contacted Tower. Was told to cancel all restrictions and cleared to land. Knowing the area very well; I stayed in visual contact with airport and landed. After landing called Maintenance and told them of the lock up I had on the navigation system. After the systems were shut down I ordered GPU hook up and turned avionics back on and everything was working. I have never seen this happen before I thought I had symbol generator #1 problem and when we switched to #2 it all worked and we continued our flight. We left for two leg flight the next day everything worked. I have ordered another computer system that operates most all autopilot and NAV systems. Whatever locked up the system somehow corrected its condition when power was removed after shut down. I had a lot of VFR options for landing at other airports; but having a visual contact with my destination made the most sense. Having back up systems are great but having the kind of lock up in the NAV system changes the landing options to VFR only. Knowing the system the way I do; some sort of electronic lock up occurred and may never happen again but replacing the main computer system should prevent it from ever happening again.

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.