From the network guidelines:
When shouldn't I comment?
Answering a question or providing an alternate solution to an existing answer; instead, post an actual answer (or edit to expand an existing one);
Should Aviation deviate from the SE network guidelines and allow answers in comments?
No, we should not.
It is true that we are more lax on comments around here, but such "answers" can neither be commented upon (without creating massive comment discussions), nor downvoted if necessary. Moreover, they are completely outside the normal review process, and normal flags are not applicable to them. More importantly, this is not what comments are for. Comments are for requesting more information and suggesting improvements, not answering the question.
I'm not immune, I've also posted similar comments in the past, this is not a good excuse to avoid improvement.
If you have an answer, please post it as such. If you don't have time to post a full answer, post it later, we are not StackOverflow, a few hours delay in posting an answer is not the end of the world.
Moreover, I cannot see what would make Aviation special and a place where such comments would be somehow beneficial, as far as I can see, there is not a single SE site that accepts them.
And to conclude, you can see from this meta post on a sister site that community managers are actively deleting them and asking not to have such kind of comments, I do not see any reason for which to go against the site administration.
No.
Comments are ephemeral. They are for asking clarification or leaving constructive criticism. They are not for answering a question or providing an alternate solution to an existing answer. It is very clearly mentioned on our privileges page.
Regarding the situation where one has only a partial answer, then post a partial answer and mention it. Each answer on a question does not have to be a complete, perfect and candidate for the acceptable answer.
As an example, look at this partial answer I provided on a very famous question. It is not the complete answer, yet it was well received (at least it appears that way).
This is a very long an interesting read about comments.
There's a nuance here I'd like to point out.
The question didn't make it clear whether it was asking only about comments posted below questions, or also about comments posted below answers.
A related answer said "Comments are for requesting more information and suggesting improvements, not answering the question."
A suggested improvement listed in a comment below an answer could in some ways be construed as "answering the question in a comment", but constructively suggesting limited improvements to existing answers falls outside the scope of the behavior we are trying to discourage.
Reasons why an improvement to an answer might be suggested in a comment, rather than in an outright edit, include--
It's an expansion to the original meaning of the answer, and commenter is not certain that the original author would agree that the new content is correct, or think that it improves the answer.
It's a (constructive) suggestion that the original author re-consider and correct some limited portion of the content of the answer-- (obviously not a total revision, in that case it would be better for the commenter to just make a new answer that contradicts the existing one(s)) (Also, this statement is not intended as a justification of "extended conversation/debate" in comments!)
Commenter has reason to suspect that additional changes might be soon made to the answer and commenter wishes to minimize total number of times question is bumped up to the top (and/or the total number of times the question is bumped back onto the first page) of the active questions list by an edit after a significant period of inactivity-- so chooses to simply suggest the edit in a comment rather than making it outright.
