Fancy automatic systems like that one are rare, but celestial navigation done by hand used to be quite common on board commercial aircraft. Making a long flight over the ocean in decades past, there really was no other way to keep track of where you were with any sort of accuracy. This lasted well into the jet age. Early 747s had a sextant port so that the navigator could use it to get a position fix.
There are rumors that the 747's sextant port fit a hose pretty well, and could be used as a nice vacuum cleaner while at altitude.
> The mounting location for the sextant remains in current 747 designs since it was originally designed and certified with an installed sextant. The sextant (and all associated hardware) has long since been removed with the advent of multiple, highly reliable long-range navigation systems. When installed, there was no requirement to depressurize the aircraft.
No requirement to depressurize, but it had the potential.
The "vacuum hose on the sextant port" thing sure sounds like an urban legend. On the other hand, it also sounds like the sort of thing some of my old pilot friends would try.
There are rumors that the 747's sextant port fit a hose pretty well, and could be used as a nice vacuum cleaner while at altitude.