Flying

You are able to fly if you are an Aarakocran, are an immortal, or have
the fly spell cast on you. But common sense tells you that things
usually are not constantly in flight - they land to rest or sleep, to
enter buildings, go underwater where you don't fly but swim, and so on...

So, we have 2 commands, FLY and LAND. FLY lets anyone capable of flight
to become airborne. LAND takes anyone airborne and sets them back on the
surface.