Airplane toilet seats: Up or down?

At the risk of offending half the population of the world, and embarrassing my mother for my bad manners, allow me to ask a question: When finished using the lavatory on planes, should men leave the toilet seat up or down? I know and abide by the rules around terrestrial toilets used by both sexes: leave the seat and lid down when done. It’s the right and polite thing to do. But are rules in the air different?