Decades ago, I worked in the TACAMO
aircraft, the older KC-130 version. TACAMO was a US Navy aircraft charged with maintaining communications with nuclear submarines in the event of nuclear war. The aircraft had a small "sunroof" and it's sole purpose was to allow the navigator to see the sun and stars so he could use the sextant that was part of the issued equipment. The idea was that there would be no radio navigation aids left when their mission was over and they had to return to
... well anywhere they could land since the survival of any airbase was not guaranteed.