Accuracy of celestial fixes


Sextant and LOP Accuracy




Federal Aviation Regulations, Part 63, Navigator Flight Test , see ground test items 3 and  4, and flight test item 37. (During the ground test, no error greater than 8 NM and average error no greater than 5 NM. In the air, 10 NM.)


American Practical Navigator, H.O. 9 (1962)

Smooth air, 5 to 10 miles.


Page 417



Air Navigation, H.O. 216 (1941)


Page 182


Page 183


Air Navigation, AFM 51-40 (1951), Page 206

Smooth air, 3 to 8 miles.




Air Navigation, Weems (1938)


Page 313
Smooth air and averaging sights, 5 to 6 miles.

Page 314 & 315


Page 316


Page 362 & 363


Page 364 & 365
Noonan himself writes to Weems that his accuracy is ten nautical miles



Page 424 & 425

Noonan's report on navigation, April 29, 1935

Noonan's newspaper article, March 22, 1936


See also:

Recent landfall approach evaluation of Noonan's method

Four observations were taken. The first observation was 3' too high; the second, 2' too low; the third observation, 6' too high and the fourth was 1' too high which produced errors in the LOPs of 3 NM, 2 NM, 6 NM and 1 NM.

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The following links report on a test flight with three guys who had never taken sextant sights in flight before. Five averaged sun observations were taken and the errors in these observations were 2 NM, 3 NM, 8 NM, 10 NM and 18 NM. So even beginner observers can obtain observations sufficiently accurate to find Howland.

http://www.fer3.com/arc/m2.aspx?i=111467&y=201001

http://www.fer3.com/arc/m2.aspx?i=111476&y=201001

http://www.fer3.com/arc/m2.aspx?i=111492&y=201001


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