Non-vulgar way to express an "Oh shucks!" moment?

That muscle-tensing moment in time when you realize that you are watching a disaster unfold before your eyes and there's absolutely nothing you can do about it.

An "Oh, Shit!" moment is the perfect way to capture this, but I need it for formal correspondence where the vulgarity is unprofessional.

Here's an example of the sentence I want to use:

It was not an "Oh, Shit!" moment for him, so I did not respond with an "Oh, Shit!" sense of urgency.

Solution 1:

You might consider emergency or one of its synonyms. Here is some information about the word from ODO:

a serious, unexpected, and often dangerous situation requiring immediate action.

"your quick response in an emergency could be a lifesaver"

synonyms: crisis, urgent situation, extremity, exigency; accident, disaster, catastrophe, calamity; difficulty, plight, predicament, danger

"a military emergency"

arising from or needed or used in an emergency.

modifier noun: emergency

"an emergency exit"

synonyms: urgent, crisis; impromptu, extraordinary

"an emergency meeting"

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Oxford Living Dictionaries

At the very least it might be a good place to start a thesaurus search.

The term uh-oh moment also came to mind, but that's probably a little too childish for what you're going for.

Solution 2:

Oh, no!

It was not an "Oh, no!" moment for him, so I did not respond with an "Oh, no!" sense of urgency.