Until about 10 years ago, the sextant was used in aviation as well. The RAF continued to use them until the wide availability of GPS made them obselete.
The aviation periscopic sextant was a precision instrument and could be used to measure depression angles as well. There was a formula to calculate your range from the depression angle and your height relative to a ground object. As it also had an azimuth ring which was accurate to about a degree or so, you could get an accurate range and bearing fix from a ground feature with a single observation.