AHRS Recalibration

[Ray93J]

Add the ability to calibrate to zero AHRS ADS-B receiver to allow unit to be recalibrated and operated in the vertical orientation. iFly does not offer that feature. AHRS units must be placed on the glare shield which exposes it to more heat than if it was installed vertically on a side window. STRATUX and Dual allow recalibration to vertical using their tools.