Majority of all aircraft that have autopilot capabilities are equipped with a IAS/Mach Selector on the AP panel. What this does is allows pilots to set a speed in Mach and IAS, regardless of altitude.
Infinite Flight automatically switches to Mach speed when above FL280, and switches back to AIS when below FL280.
I would like to suggest that Devs implement a selector for this, it could be added into the AP interface and be the same as the APPR NAV’ button
IAS/MACH Number Changeover Switch (Top Button) on the A/P Panel of a Boeing 787.