I also find it hard to believe that in what was undoubtedly hours of helicopter footage, there wasn't a ten second stretch in which they weren't visible, but whatever...
They're noticeable on the blu-ray (at 1.78), and I've seen the film projected at 1.85 on several occasions and they're still visible, though not obvious. If it's something you're not aware of, it probably wouldn't stand out.
https://www.mutedhorn.net/the-shining