It's a given the search capability wasn't there. It's also a given there
was a war warning out. I'd think a prudent commander would do the best he
could with the assets he had. Formulate some threat axes. 270 would be
more likely than 090. Application of a little common sense (your enemy
might like to avoid detection, therefor he's likely to give your forward
bases: Wake, Midway, etc) might refine that considerably. There's even a
discipline (Operations analysis, senior course at USNA) that's intended for
problems just like this: maximization of search detection with given
assets.

So maybe you wind up with a pattern that gives a PsubD of 30%. An educated
guess (threat axis either NW or SW of Pearl) might sweeten that
considerably. And you FLY! They had SOME search capability, why not use
it? Instead they played staff games ... memos flying all over the place.
Can't do a full search, so we'll ask for the assets (non-existent) and sit
on our hands till we get them.

The underlying problem was that while a Japanese attack was expected, no one
knew where it might occur. But on Oahu in early December 1941, everyone
knew, in their hearts, it couldn't happen there (or if it did, it would be
sabotage by all those Japanese living on the island).

R / John