I think that the additional weight on the water on the surface of the outer airplane body increases friction with the air, and also weight of the aircraft. But does the fuel consumption increase? And by how much?
I think that the additional weight on the water on the surface of the outer airplane body increases friction with the air, and also weight of the aircraft. But does the fuel consumption increase? And by how much?
I don’t know much about it myself, but I would guess it is negligible. Maybe for small propeller machines with a fairly limited amount of fuel capacity; but larger planes, especially commercial ones, have reserve fuel for quite some time.
Situations where landing at the destination is temporarily unavailable, air traffic requires the plane to circle for some time, or they are even rerouted to a different airport can always occur and are accounted for. A minor increase from rainfall shouldn’t make a dent. I would think.