Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Commercial
Flight Crew Last 90 Days 25; Flight Crew Total 815; Flight Crew Type 300
Other / Unknown
Aircraft Equipment Problem Less Severe
General None Reported / Taken
Aircraft; Human Factors
I fly an aircraft with an IFR-certified Garmin GNC300XL; which is a non-WAAS GPS receiver. We have been noticing lately that this unit is drawing incorrect courses from our present position direct to GPS waypoints. Sometimes the unit will draw the correct course; and while we are enroute on that course; it will completely re-draw an incorrect route to the same waypoint. Sometimes the unit will completely delete all waypoint information and leave us with no course to follow whatsoever; as though the unit has just been initialized and is waiting for us to input information.While enroute to our destination airport on a VFR training flight; the unit erased our course and waypoint while we were 15 miles southwest of the destination. We simply reverted to pilotage to continue to our destination airport.This could; however; present a real problem to GNC300XL operators; especially during IFR conditions; hence the reason for this report. While searching for the solution to this problem; we are limiting the unit for use during VFR operations only.
An IFR-certified Garmin GNC300XL installed in a C150 began giving faulty information related to courses and waypoints.