I'm trying to figure out how this carry-on bag rule works in practice:
Onboard the aircraft, all carry-on baggage must be stowed under the seat or in the overhead compartments. Porter may require that an item of carry-on baggage travel as checked luggage if the bag cannot be safely stowed in the cabin.
My rolling luggage meets the size requirements, maybe even the weight requirements for the three-night trip I'm planning out of IAD in late May, but there's no way it fits overhead on a Q400. It will fit underneath a seat, but then the seat behind had better stay vacant. So will they gate-check the bag for free--meaning I should eat the $22 extra a Standard fare would cost over Basic--or will they not, meaning I should buy a Basic fare and eat the checked-bag fee on that?