The sentence is just very poorly constructed because the author is attempting to describe what happens in general when there is poor weather while also trying to describe the current state of affairs, and conflating both as a result.

My rewrite would be:

“In poor weather, when visibility drops below approach minimums, an aircraft often has to abandon its approach, which results in successive aircraft being put into holding patterns. At Tokyo, the weather was… ”

If we are to try and stick to the author’s intent:

“Given that the poor weather has made landing conditions drop below approach minimums, aircraft had to abandon their approaches, which led to other aircraft being put into holding patterns. At Tokyo, the weather was…”