Garmin SERVICE ADVISORY,NO.: 1510 Rev A GDU 620 Software Version 6.21


G500, G600, and G500H Series products using GDU 620 main software version 6.21.


Flight crews may observe unexpected display issues such as flashing “NO AP DATA” annunciation or intermittent display of the Flight Director cue. The condition can also cause intermittent display issues related to ADF, Weather Radar, and Fast/Slow (PC-12 aircraft only).

These issues can be caused by a fragmented Terrain Database file on the Database Card.


• No action is required if the display does not exhibit the issues described above (not all GDU 620 displays are affected).
• If the aforementioned issues are observed:

  1. Crew should closely monitor altitude capture performance if the G500/G600 is used for automatic altitude capture (i.e. altitude preselect).
  2. Contact Garmin Aviation Service Center or Dealer for a replacement Database Card that is marked MOD 1.


The MOD 1 Database Card will be provided to resolve the issue. Future shipments of affected data cards will include MOD 1 status.


35 years component-level Aviation/Electronics repair/Avionics retrofit experience. FCC General Radiotelephone with Ship Radar. Navcom-Audio, Transponder-Pulse-Radar, Autopilot expertise. IT Administration since 1983. Private Pilot since 1986. CAD designer since 1990. FAA Certified Repair Station Chief Inspector since 1994. Started 3 Avionics Shops. College: Business Administration/Marketing. Motorcycle enthusiast. 6 year USAF Veteran, Ground Radio Equipment Technician (30474, E-5). WordPress novice.

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