[ampdepolymerase]

You need clear view of the sky and big lenses (you can always use more compact metamaterial lenses and infrared imaging for cloudy days but they are as expensive if not more than INS). Star charts also drift over the years and you will have the same problem as magnetic true north where the database needs to be updated regularly. Fine for airliners, not so great for skyhawks.

[adolph]

An automatic celestial navigation system for navigating both night and day by observation of K-band or H-band infrared light from multiple stars.

https://patents.google.com/patent/US7349803B2/en

In this celestial map, the bodies of the solar system are placed so exactly that those versed in astronomy could calculate the precession (progressively earlier occurrence) of the Pole Star for approximately the next 14,000 years. Conversely, future generations could look upon this monument and determine, if no other means were available, the exact date on which Hoover Dam was dedicated.

https://www.usbr.gov/lc/hooverdam/history/essays/artwork.htm...

[JKCalhoun]

I'm imagining a navigation system by trying to pattern-match the earth terrain with a downward-facing camera from the plane.

A suitably large database of satellite photos covering various conditions, day, night might work for all cases but cloudy (when the plane is above/in the clouds).

[fbanon]

Already exists: https://en.wikipedia.org/wiki/TERCOM Since the 1950s!

[JKCalhoun]

Oh yeah, contour-matching. I remember this being touted with regard to U.S. cruise missiles in the 80's, 90's.

Guess radar + countour is more reliable than camera + imagery.

(I'll crawl back to the 1800's now.)

[maxden]

They've used that landing on Mars as well, Terrain Relative Navigation.

[cm2187]

Yeah I guess that wouldn’t work during takeoff and landing. But for the most common airliners (a320 to a380 and boeing equivalent): are there clouds above their cruising altitude? By day I presume you could use the sun.

[p_l]

Some early jetliners had special cupola for star navigation, but it soon fell out of use because NDB, VOR, DME and other radio systems were easier and better.