Is this double-decker seat the future of airplane travel?
https://edition.cnn.com/travel/article/zephyr-seat-double-decker-airplane/index.html
Though the inventor says the space above passengers can be usable, it's difficult to fully use the space for seats on the 2nd floor.
To create space for them, seats on the 1st floor must be lower or the ceiling of the 1st floor must be lower. It means the 1st floor can be just for sleeping, due to lower ceiling. But, in this case, it's impossible for passengers on the 1st floor to eat inflight meals.
