Originally Posted by
canadiancow
The aircraft generally flies with a positive angle of attack.
If the seat is parallel to the floor, your head will be lower than your feet, which really sucks.
If the seat is perpendicular to gravity, you get what you want.
Can you clarify what you mean by "truly flat"?
This is my observation as well. The slight angle of the top part of the seat is close the the angle of attack. It "feels" flat to me. It hasn't prevented me from sleeping.