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Aviation Alerts and Advisories

Service Alert 1027 Rev B: Aircraft with Maximum Airspeed Limitations that Vary with Altitude


G500 and G600 Systems with Software Version 3.02 or earlier, that have a maximum airspeed limitation that varies with altitude. A list of known affected aircraft on the G500/600 AML is listed in Table 1 of this alert. Rev B of this alert lists additional aircraft (added models are highlighted in grey).


Certain airplane models (see page two of this alert) on the G500/600 AML, require a maximum airspeed indication (“barber pole”) that will change based on altitude. GDU 620 Software Version 3.02 in G500/G600 Systems does not currently provide a means to display a maximum airspeed indication that varies with altitude. This could result in the display of maximum airspeed indication that is higher than the actual operating limitation.


Garmin will support the display of maximum airspeed indications that vary with altitude in GDU 620 Software Version 5.00 and later versions. When Software Version 5.00 is STC approved, an upgrade will be announced.


For affected aircraft: The current G500 and G600 STC Installation Manuals, (Garmin p/n 190-01102-06 Rev 3 and 190-00601-06 Rev E, respectively) require that aircraft models affected by this issue retain the original airspeed indicator and/or airspeed limitation placard. (Some of the affected aircraft models originally used a moveable maximum airspeed indication on the airspeed indicator and other models used a placard, to depict the maximum allowable airspeed.) The pilot is to rely on the secondary airspeed indicator and/or placard for the maximum airspeed limitations.

The current AFMS contains a description of this limitation. Review the AFMS installed in the aircraft. If AFMS Rev. C (G600) or later or Rev. 2 (G500) or later is installed, verify that section 2.8 is filled out for the installation. If AFMS Rev. B or earlier (G600) or Rev. 1 (G500) is installed or section 2.8 has not been filled out, contact your Garmin dealer.

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