Given the contradictory claims by pilots themselves on the subject, I will go ahead an assert I am correct on both.
Good way to prove yourself right I guess, just assert yourself to be correct.
From this thread it sounds like you can't see it on most flights (I travel quite a lot with work but have never noticed a curve).
From Concorde though, which flew higher, it does sound like you could see it:
https://www.flyertalk.com/forum/travelbuzz/633492-pilots-when-can-you-start-seeing-curvature-earth-sky-black.htmlBut you guys have that covered anyway with this Wiki page:
https://wiki.tfes.org/High_Altitude_PhotographsThis is one of the somewhat frustrating parts of flat earth theory, a lot of it is "Heads I win, tails you lose"
FE: The horizon is flat, that proves the earth is flat
RE: Well, no, it's just at ground level the curve is too small to be detected. At high enough altitude you can see the curve
FE: That's just the spotlight of the sun
RE: What? You literally just said there isn't a curve!
FE: Yes, but...LOOK OVER THERE! *runs away*
FE: (to other FErs) We won another one! *high fives*