Power off when external USB power is turned off

Hi,

Just upgraded from a Mini to a Mini 2.

The "original" Mini had a setting to turn off the device when USB power is turned off. This is very helpful for example in an aircraft cockpit where you want the device to turn on at the beginning of the flight and automatically turn off once the aircraft power is turned off. 

Cannot find that setting on the Mini 2. Am I missing something or is this feature missing in the current firmware version?

-Sven