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I bought "Amelia Earhart: The Mystery Solved" by Elgen and Marie Long
(1999).

https://www.elgenlong.com/publications/amelia-earhart-mystery-solved.html

https://www.simonandschuster.com/books/Amelia-Earhart/Elgen-M-Long/9781439164662

Regarding turning back to Lae, Long makes a couple points:

1. The Electra had a small supply of 100 octane gasoline, which Earhart
expended during the heavily overloaded takeoff. There was only 87 octane
at Lae, so a return would mean a lengthy wait for more high grade fuel.
She may also have been reluctant to subject the engines to the
punishment of another takeoff.

2. Lae had no runway lights. By my computation, the last quarter Moon
set at 02:23 GCT (1223 local) and evening twilight ended at 08:30 GCT
(1830 L). Since GCT is also the elapsed time since departure, they would
have to be back at Lae within 8.5 hours after takeoff or face a night
approach to a field with 10000 foot mountains on three sides. If they
wanted to loiter and wait for light, the Moon rose at 15:02 GCT and
morning civil twilight began at 20:01 GCT.

The book does not discount the option of turning back, but notes those
factors as additional constraints.


Elgen Long flew in Navy patrol planes during the war. When they operated
out of the Phoenix Group, "it was always a daylight flight. and there
were usually only sun lines available for updates, but the fliers never
experienced any trouble finding Howland or Baker Islands. Of course they
had the advantage of knowing the islands' true position and were trained
in the best techniques developed earlier by pioneers like Earhart and
Noonan."

Regarding that "true position," Long says, "Howland Island is actually
about 6 statute miles east of the position shown on Earhart's chart. ...
This may not seem to be a significant distance, but when you realize
their visibility eastward may have been reduced to 15 nautical miles by
the early morning sun, the mismapping of the island becomes more
important." (ch 16 p 241)

A footnote credits that information to a USCG letter of August 12, 1936,
and the chart by navigation consultant Clarence S. Williams. The chart
may be this document online at the Perdue U collection:

https://earchives.lib.purdue.edu/digital/collection/earhart/id/2860

On the other hand, someone (Gary LaPook?) said Earhart did have the
correct Howland coordinates.


On August 5 Howard G said "However, as I have mentioned before - after
the big crash in Honolulu I see no evidence she did a recal of the
compass and assume it was probably accurate +- 5 deg - however did they
fly a true heading - allowing for local variation between magnetic and
true - over that distance it would change."

According to Long, after they arrived at Miami for the eastbound
circumnavigation, "Fred wanted the compasses swung for a deviation
check... They turned the airplane completely around, stopping at points
to check the compasses... The tail of the Electra was raised up onto a
wheeled dolly so the plane would be in flight attitude during the
compass swing."

"Amelia and Fred took off and flew along a half dozen test courses that
Fred had laid out for Pan American several years before. He found the
compasses preforming about as accurately as it was possible to get them."

I find it inconceivable that they would neglect to apply magnetic
variation during the flight to Howland. (The Williams document includes
a chart with isogonic lines.)

--
Paul Hirose
sofajpl.com

   

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