Originally Posted by
mvoight
If it says they must understand on "or" the other, then that doesn't mean both.
I agree with this statement narrowly, but it doesn't *say* "must understand one OR the other", it says:
"No certificate holder may seat a person in a seat affected by this section if [...] The person lacks the ability to read and understand instructions required by this section and related to emergency evacuation provided by the certificate holder in printed or graphic form or the ability to understand oral crew commands."
I realize this is FT but it would help if people actually read the text of what's being discussed.
If the text is supposed to require them to understand both, then it should say "and". or the author of that writing doesn't understand the difference between "and" and "or".
I also agree it would be clearer if, instead of what is effectively a double negative (and the source of everyone's confusion), it was rephrased in an affirmative manner: "passengers seated in this section must be able to [A] and [B]", but it the problem isn't that the author doesn't understand "or" it's that too many people don't know De Morgan's Law.
If you express this as P = "can sit in the exit row", A = "can read printed or graphic form", and B = "can understand oral crew commands" then as written in the CFR
P = not (not A OR not B)
which by De Morgan's law, if you want to combine the outer and inner "not"s
P = (not not A) AND (not not B) = A AND B
They're logically equivalent.
If that's too abstract to deal with, refer instead to my Spanish-English translator example.