NavList:

>>Has anyone silvered a mirror lately in an emergency, or perhaps repaired a chronometer? Celestial navigation is merely an old fashioned 'black box' requiring a bit more of the navigator..."<<

Milton Freedman, in a program broadcast on PBS in 1980, said:

Look at this lead pencil. There’s not a single person in the world who could make this pencil.

Remarkable statement? Not at all. The wood from which it is made, for all I know, comes from a tree that was cut down in the state of Washington. To cut down that tree, it took a saw. To make the saw, it took steel. To make steel, it took iron ore. This black center—we call it lead but it’s really graphite, compressed graphite—I’m not sure where it comes from, but I think it comes from some mines in South America. This red top up here, this eraser, a bit of rubber, probably comes from Malaya, where the rubber tree isn’t even native! It was imported from South America by some businessmen with the help of the British government. This brass ferrule? I haven’t the slightest idea where it came from. Or the yellow paint! Or the paint that made the black lines. Or the glue that holds it together.

Literally thousands of people co-operated to make this pencil.

If celestial navigation is a black box, because hardly any navigator knows how to re-silver his mirrors, then we would have to say that an HB pencil is also a black box.

But once we go that far, we have such a broad definition of "black box" that it has ceased to be a useful description of anything at all.

Celestial navigation takes a good bit more training/background to use than the GPS receiver built into my smartphone...but once you acquire enough knowledge to perform celestial nav at all, it is certainly more transparent in its processes than my cellphone.  So I would say, "No...sextant navigation is not a black box, not in the same way that cell-phone GPS navigation is black box."

Bob