[bryondowd]

Makes sense that a cockpit wouldn't need a clear distinction between brackets and parenthesis, or |. But I am surprised about the similarity of 0 and O. I recall when I went to the ATC academy they really drilled in using a horizontal slash through zeros when hand-written. Also had to underline the letter S in any case where it could be ambiguous with the number 5 (as in a plane's tail number). I think we also had to put a horizontal strike through the letter Z to distinguish it from a 2.

[_moof]

Probably more important in an ATC context than a flight deck setting. Tail numbers come to mind, as you said. Although I could see Part 91 operators mixing up airport identifiers with O and 0, airlines don't fly to airports where that matters... intersections and navaids are all alpha... approach names aren't going to have any ambiguity... so I guess one could argue it's ok? Still, you're right, it was a weird choice not to disambiguate them.

(Also, I'm super jealous you went to the ATC academy. By the time I seriously considered it, I'd aged out.)