The boy sat. That could be a subject. The predicate is the half-sentence you have right now. So, it could be The boy sat in the window seat on the plane.
Explanation:
A subject contains the noun. A predicate contains what the noun does.
It's a redundant sentence because it does not need to say "over and over" and "and repeated it. Also those two phrases are double negatives. It could also be called a run on sentence.
