How about "suddenly"/ all of a sudden? It basically means abruptly, not at a definite moment of the descent. That's how I'd say.

Suddenly I started to shout at....

I would agree that Sergey, Liliana and Nancy Lynn are all correct. It's a stylistic matter at that point depending on the full context, and all three of these options are preferable to the three possibilities in the source term I think.

if you preferred to keep the word 'moment'

I knew I needed to keep it together to drive safely and yes, there was a moment when I started to go into a sort of an impromptu speech. ...
https://beta.blogger.com/comment. g?blogID=13561217&postID=114582231076761598

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Note added at 20 mins (2006-09-29 22:43:09 GMT)
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but then - at one moment - is fine too:

At one moment Herenda fainted, probably as a consequence of his wound, ... For example, at one moment he talked about the training they received in Metkovic ...
www.balkanpeace.org/cib/bos/wctb14.shtml

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Note added at 27 mins (2006-09-29 22:50:29 GMT)
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and why is that, sophia?!

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Note added at 30 mins (2006-09-29 22:52:53 GMT)
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imho in your comment is totally inappropriate, don't you think? as it stands for 'in my humble opinion' i believe? you need to learn to substantiate your comments, otherwise you come across as rather abrupt...

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Note added at 1 hr (2006-09-29 23:34:56 GMT)
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so, what are you neutral about, nancy? you haven't made one single linguistic comment about my entry.
and i do not take it personally. 'abrupt' in english means 'brief to the point of rudeness;
syn. curt.


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Note added at 9 hrs (2006-09-30 08:19:36 GMT)
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thank you, CC: i think mr forstag's comment is a good example how blabbing about being a native speaker (even an apparently educated one) is not always a good thing.

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Note added at 10 hrs (2006-09-30 08:33:53 GMT)
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thanks, dusty, for finding my suggestion a perfectly acceptable native english one.

i offered it because the asker was grasping for the right one with the word 'moment' in this particular situation - when they were coming down the stairs.



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Note added at 10 hrs (2006-09-30 08:41:13 GMT)
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oops, noticed sophia's new comment.

it's good practice to keep your old comment (instead of deleting it) and add another one space permitting, otherwise proz.com users find it difficult to follow.

you might find that starting your construction with 'no need...' was rather awkward in polite conversations.

and finally, nancy, why don't you follow the rules like the rest of us and use 'peer comment' field for strictly linguistic purposes.