Given some other character, sure. How many times has powered flight
been lost in _Avialae_? I'm thinking at least 11, probably more (not
even counting multiple losses among palaeognathes).
Much more often among rails alone -- 2000 years ago, every small Pacific
island had its own species of flightless rail, and the big ones had two or
three, never mind the occasional flightless parrot or duck or ibis or...