Revision A9 32
GRT Avionics Mini-X Installation, Setup & User Manual
4.8 Altimeter Calibration
When the Mini is to be used for IFR flight, the altimeter portion of the AHRS must be calibrated to
conform to FAR 91.411. This is to be done at an interval in time as dictated by FAR 91.411. It is not
necessary to calibrate the altimeter more often than this requirement.
The accuracy of the altimeter can be adjusted using entries provided on this page to account sensor
errors that may occur due to aging. The adjustments are stored within the AHRS/Air Data Computer.
Partial Altimeter Calibration – Correcting Altimeter vs Baroset
This calibration adjusts the relationship between the altitude display and the barometric pressure
setting. This calibration does not require an air data test set, and may be performed on an annual
basis, or as needed as follows:
1. Position the aircraft at a location with a known elevation.
2. Turn on the Mini and allow at least 5 minutes to elapse before continuing.
3. Obtain the current barometric pressure setting. This setting should be provided by the airport
at which the airplane is located, or a nearby airport, and should be as recent as possible.
4. Access Set Menu > Altimeter Calibration.
5. Use the knob to highlight Calibrate- OFF. Rotate the knob to turn it ON.
6. Set the baroset to the currently reported altimeter setting.
7. Use the knob to highlight the Bias setting. Adjust the setting until the altimeter matches the
airport elevation. (Note that there is about a 2 second delay until adjustments are reflected
in the displayed altitude.)
8. Press the SAVE softkey, then EXIT. Calibration is complete! Do not alter any other altitude
settings. The altimeter calibration will be turned off automatically when this page is exited.
