Originally Posted by
DespairingTraveller
I believe that approximation is only valid near sea level.
I went back to basics and did the trig. I may have made a mistake, so would be happy to be corrected if someone wants to check the calculation.
DT, no, the results are additive - we used 1.14 for nautical miles so:
1.14*sqrt Ha + 1.14*sqrt Ho would for 37k and 250 feet give 219 + 18 = 237 nm.
Now there is a phenomenon of analogous propagation where the light waves are bent by atmospheric ducting. However at night I believe such ducting is unlikely. One would conclude that an observer at 370 miles (nm or statute) would be unsighted. Now if that distance was kilometres
