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I'm not sure what eight degree difference you are talking about.

Clarence Williams was hired by Earhart to do some of the planning for 
the world flight. Since the original plan was to travel westward he 
calculated the leg from Howland to Lae with an initial great circle 
course of 257.3° True. He then applied the variation of 9° East 
resulting in a Magnetic Course of 248.3°. When they reversed the route 
they simply subtracted 180° from the prior computations making the 
inbound course to Howland 68.3°° M, 77.3 T.  My calculations came up 
with 77.6° T, rounded to 78° T essentially the same result as Williams. 
The distance is 2222.6 NM, 2556.0  SM, the same as Williams' calculated 
distance. See attached Williams' documents.

He used 6° 47' S, 147° 00' E for the location of Lae and 0° 49' N, 176° 
43' W for Howland. The coordinates for Lae, based on the official 1935 
Australian chart (New Guinea was administered by Australia at the time) 
are 6° 48' S, 147° 02' E an insignificant difference from the 
coordinates used by Williams. See attached chart.

Williams used 0° 49' N, 176° 43' W for Howland, about 5 nm west of the 
actual location given in the 1938 Bowditch as 0° 48' N, 176° 38' W. This 
is what gave rise to the theory that Noonan was aiming for the wrong 
coordinates, causing him to miss the island. But Williams did his 
calculations early and the correct location of Howland was determined by 
the Itasca after Williams had completed his work but well before Earhart 
departed on the second, eastbound, attempt so these correct coordinates 
may have been available to Noonan for his approach to Howland. Either 
way, the error was not great enough to cause them to miss the island.

I have checked Williams' work and the points that I calculated for the 
great circle are within two nautical miles of the ones listed by him. My 
calculations show that the initial GC course from Lae was 79.5° T and 
the final course was 77.6°  T, a change of less than two degrees. The 
numbers shown on Williams chart show a greater change of five degrees 
but his are magnetic courses and the variation changed by about three 
degrees from Lae to Howland accounting for this difference, see the 
charts at:

http://www.fer3.com/arc/m2.aspx?i=110847&y=200911


I have attached a place mark file to take you to Howland on Google Earth.



The rhumb line course from Lae to Howland is 78.2°  T and the rhumb line 
distance is 2222.7 NM, only one-tenth of a mile longer than the great 
circle since the route was along the equator.

gl




Ted Campbell wrote:
>
> On William's Nav guide for this flight he had a course of 68 degrees 
> from Lae to Howland. How would this 8 degree difference effect your 
> analysis if AE and FN followed this line?
>
> Ted Campbell
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