The unaffordable expenses that occur after one arrives at a destination.
A wedding is being planned and the high a maintenance bride who is a stewardess and is reasoning with everyone that she wants the wedding to be in Hawaii. She explains that she can get very low cost flight tickets for everyone. Many in the two families want to go but are not that well off. Someone says "yes, but that plane has to land sometime." That means that the low cost flight tickets are appreciated but the huge expenses start once the plane has landed like taxi cabs or limos, motel rooms in Hawaii, tipping skycaps, cabs, luggage handlers, buying drinks at a renowned resort where prices are inflated, thus the idea of low cost flight tickets is irrelevant.
"That Plane" is a bit of a take on "those plans."