Sometimes it is not possible to extend code within the if statement of a ::instance().isEnabled().

To extend functionality in these scenarios, it would be beneficial to be able to check is flight features are enabled from custom code, to be consistent with standard functionality. As of this moment that is not possible, since flight classes are internal.

This would be an easy fix by just replacing the 'internal' keywords of both the class and the instance() method with 'public' in all flight classes.