This is gramatically correct. "which" is the right replacement for "altitude" when lumping two sentences into one sentence. If we split it into two sentences then "which" becomes "it"It's the altitude before reaching which a decision has to be made whether you will continue to approach or go around.
Is "the altitude before reaching which" gramatically correct here?
I'm afraid I think it needs the comma you've removed from my sentence. Otherwise going round sounds like a form of approaching, to my ear.I guess It's the altitude before reaching which you have to make a decision whether you will continue to approach or go around sounds a bit better.
I thought this might have happened. I wasn't altogether serious. I should learn to use emoticons.I haven't removed anything from your sentence, I composed my version independently. I replied to your original post before I saw the additions you subsequently edited in.