Celestial - Airborne
But then airborne celestial is quite different from maritime in practice.
The sextant is different, all calculations are done beforehand rather than after the shooting, and additional corrections need to be made for speed, altitude, coriolis, course deviations etc. It's actually quite more complex. But very satisfactory once accomplished.
best performance to be expected is 2 nm, but 5 - 10 nm is more realistic. Doesn't sound great compared to GPS, but it gets you to that island airfield out in the pacific. I have recently achieved 5 nm in a self-restored WW2 bubble sextant while in a microlight aircraft.
I have a few of these devices and learnt the skill recently. Would be willing to help out anyone interested.
Eric