NavList:

David Iwancio you wrote:
I saw that false horizons was brought up here back in 2020, with mention that it may just be anecdotes from navigators looking to avoid extra work.  But has there been any real research or writing on the phenomenon beyond "Don't shoot the moon at night?"

I'm asking because I'm wondering if it could be explained by the dip of the horizon being signifigantly different at night than during daylight/twilight hours.

David

I thought this was an ‘an air navigator’ belief, and that usually involves bubble or pendulous reference sextants, so dip rarely comes into it.  There have been relatively few schools of air navigation, so myths tend to perpetuate.  An instructor tells a class something, and a couple of years later the students come back as instructors; so myths perpetuate.  Air Navigation tends to be taught ‘by numbers’ like most drills in the Services, and anything ‘non-standard’ can easily be forgotten or applied in the wrong sense.  In the case of the Moon, you must remember to apply P in A, and if using a graticule, you might also prefer to shoot an edge and allow for semi diameter.  Also, if pre-calculating, you might have sign reversals to apply, so is a 32-mile error due to poor piloting or poor maths?  Therefore, the Moon and planets tend to be avoided at night in the tropopause when there are plenty of stars to use.  In the daytime, or below thin cloud at night the Moon and brightest planets can be very useful.  In the Services nearly all logs and charts are peer, leader, or instructor marked, even in wartime, so poor Moon shots would have been noticed.  DaveP