[rgmerk]

Hmmm. If, rather than flying close to sea level, you flew at high altitude (above commercial airliners), and kept it relatively small, I suspect that you could do this and no one would notice unless you told them.

Though at high altitudes the winds are such that it would be less of an airship and more of a steerable balloon.

[alexfernandez]

At really high altitudes air density goes down quickly; this is good for planes but bad for airships because payloads are reduced. Plus, as you say, winds are really really strong: over 200 km/h. https://earth.nullschool.net/#current/wind/isobaric/250hPa/o...

I have seen many high altitude airship studies trying to hover around, but none have been viable in the end. To go around the world it seems better to just float, as in the comment above: https://news.ycombinator.com/item?id=46881679.