Since Percy is a son of Poseidon, he feels best in the water. Since Nico is son of Hades, he feels best in the shadows. Shouldn't Thalia, who is daughter of Zeus, feel best in the sky, not afraid of it?

she feels alright with lightning

That is a good point but I think that Rick Riordan was trying to twist up the book and make it a little thêm interesting.

She's not afraid of the sky, she's afraid of heights.

She`s just scared of heights, she probably had a bad experience hoặc something (falling). I think she`s okay in airplanes, as long as she doesn`t look down. And I`m pretty sure she`s getting better, in LO she didn`t freeze on Olympus, when they were jumping off the bridge.

But yah, it is ironic.

Thats a good point. i guess she probably had bad history with being in the sky. i'm afraid of heights because my class and i went on a school field trip to the state capitol and we were at the hàng đầu, đầu trang looking over the balconcony and one of the guys were being an idiot and ran up behing me a pushed me and and i almost fell over the edge. Been scared ever since. So history really effects the human mind