This is one of those cultural memes ("The Top Gun landing was ImPoSsIbLe") that tells on the person saying it for not having read the manual. If you don't read the manual, the landing sequence is pretty much impossible to figure out. If you do, you pretty much get it the first and every time after that.
Except for those of us as kids who RENTED the game which didn't typically come with the manual...
That said, this is bad game design. A manual should never be needed.
The trick is just to know the numbers to aim for and ignore the instructions.
I had the game and the manual, but I can’t recall if I ever read the manual. I played the game a ton and was maybe 50/50 at the landings, but just followed the on-screen instructions. I could probably have puzzled out the target numbers, but never did (was it in the manual?). Now you can just google the correct values and nail it every time (paying no attention to the on-screen directions).
[edit] incidentally, my “it’s not actually hard” thing from the NES is the dam level in TMNT. It’s a challenge like the first two times you play it, then never again. It’s just not that hard. I think it’s easier than tons of Mario game levels, for instance.