Garmin G1000 Pilot's Manual page 302

APPENDIX A
System Annunciation
Other Various Red X Indications
A-6
Display system is not receiving airspeed input from air data computer.
Display is not receiving altitude input from the air data computer.
Display is not receiving vertical speed input from the air data computer.
Display is not receiving valid heading input from AHRS.
GPS information is either not present or is invalid for navigation use.
Note that AHRS utilizes GPS inputs during normal operation. AHRS operation may
be degraded if GPS signals are not present (see AFMS).
Display is not receiving valid transponder information.
A red 'X' through any other display field, such as engine instrumentation fields,
indicates that the field is not receiving valid data.
Garmin G1000 Pilot's Guide for the Quest Kodiak 100
Comment
190-00590-00 Rev. C