https://en.wikipedia.org/wiki/Slashed_zero#Similar_symbols:

”The slashed zero causes problems in all languages because it can be mistaken for 8, especially when lighting is dim, imaging or eyes are out of focus, or printing is small compared to the dot size.”

I think that can be a valid reason to use regular zeroes on all kinds of numeric indicators.

https://en.wikipedia.org/wiki/Slashed_zero#Similar_symbols:

”The slashed zero causes problems in all languages because it can be mistaken for 8, especially when lighting is dim, imaging or eyes are out of focus, or printing is small compared to the dot size.”

I think that can be a valid reason to use regular zeroes on all kinds of numeric indicators in airplanes, where context makes it clear that O’s cannot be present.

The page header on the site shows a sample avionics display, some of the 0's are slashed, some aren't.

http://b612-font.com/images/photo-header.jpg

The picture in the header does include slashed 0's though.

Edit: the pdf included in the download has both variants of 0, the slashed one at unicode point E007. So it seems it's up to the user to pick one.

I can’t think of any particular instances where a O or 0 would mix in the cockpit. Switches and panels are always labeled with letters in form of words or abbreviations. Gauges use exclusively numbers for measuring some quantity, for example EGT. In cases where numbers and letter might mix there are specific rules about not using O or 0 or even 1 and L.

Interestingly the picture in the background of the header seems to have some 0s with a cross through and some without.

How often do you see 0/O ambiguity inn non-programming context?

Probably you know usually if it's a number or text. It's more a problem in product codes etc. But yes, I agree, it would be better with crossed zeros. I even cross zeros in my handwriting.

What if upper case O was mapped to lower case o. Then only o/0 are available. No chance of confusion but could be distracting or annoying to read.. end random thought..