Polar stations are even more inaccessible during polar winter with months of total darkness and it is just too dangerous to reach them. The winter-over crews need to be completely self-sufficient until the sun rises again.
The general rule is that the Americans don't fly during the winter but they do tend to downplay and not publicize the times when they do fly.
[1] https://www.theguardian.com/world/2025/aug/06/mcmurdo-statio...