Amelia Earhart (AE) attempted to fly around the world in 1937 at about
the equator. Some prior
around the world flights had been made at higher
latitudes so encompassed a shorter route. The original plan was to fly
westward and refuel in the air over Midway Island since there was no
airport there, only a seaplane base. The Navy put the kibosh on that
plan because of AE's lack of the piloting skills for the in flight
refueling. The next plan was to fly westward including a leg from Hawaii
to Howland, about 1800 NM, where a runway was bulldozed for her use.
(There is speculation that this also furthered the claim of U.S.
sovereignty's over Howland and the other Line Islands. It may have also
furthered Pan Am's plans for routes across the Pacific.) The plan was
for AE to be accompanied by Harry Manning as navigator and radio
operator and also by Fred Noonan as navigator as far as Howland and for
AE to continue on alone after that with Manning and Noonan to return
from Howland by ship. It is
obvious that everyone appreciated that the
leg to Howland was to be the most challenging navigationally
They flew from Oakland to Hawaii on March 18, 1937 (Z) as planned with
Paul Mantz also aboard, he was a technical adviser to AE. Noonan and /or
Manning took 14 celestial shots during this flight as well as a number
of radio bearings. We have the charts used on this leg. On the
subsequent takeoff with Manning and Noonan onboard AE lost control of
the plane resulting in a ground loop and significant damage to the
plane. The plane was crated up and shipped back to California on the
Lauraline for repairs at the Lockheed plant in Burbank California. It
was decided to reverse the route to travel eastbound after repairs with
the toughest navigation leg to be Lae New
Guinea to Howland. This necessitated carrying a navigator for the the
entire flight. Manning claimed that he had to get back to his
full time
job as captain on a ship but he was supposed to have said that he had
lost confidence in AE's abilities so he did not participate in this
second attempt leaving Noonan as the sole navigator. Noonan did not have
Manning's radio skills which proved to be a serious problem later in the
flight. They flew from Oakland down to Natal Brazil. On June 7, 1937
they flew from Natal towards Dakar Senegal but missed that destination
and landed about 150 NM further north at St. Louis. We have the chart
used on this flight showing five sun lines.
They then continued on around the world and arrived at Lae N.G. on June
29, 1937. On the 30th the spark plugs were changed and other maintenance
accomplished. They had planned to depart the next day, July 1st, but
were unable to get a radio time signal so put off the departure until
the 2nd. They took advantage of the delay to do a test flight on the 1st
to check out the operation of the RDF which didn't work. They ignored
this problem and departed at 10:00 a.m. (ZD -10) on July 2nd, 0000 Z
July 2nd, for a planned 18 hour flight to Howland. This leg is 2222 NM
long and the course is 078º True approaching the island. The rumb line
and the great circle differ by less than one degree and one-tenth of a
nautical mile since the flight was along the equator. The Coast Guard
Cutter Itasca was off shore of Howland ready to transmit a homing signal
for AE to follow to Howland and had the capability of direction finding
on transmissions made by AE if she transmitted on the correct frequency
within the frequency range of the Itasca's equipment. Itasca had cabled
to Lae on June 28th listing the frequency ranges of its radios. Its RDF
covered only from 270 to 500 kHz. The Itasca maintained time with a ZD
of + 11.5. AE maintained two way radio contact with Lae for
five hours
on her daytime frequency of 6210 kHz but contact was lost when she
switched to her night time frequency of 3105 kHz to attempt to call Itasca.
AE's radio could transmit on 500, 3105 and 6210 kHz only but she could
tune her receiver to any frequency. Communications on he international
calling frequency of 500 kHz was in Morse code and neither AE nor Noonan
were proficient in Morse though manning was. Since they did not plan to
utilize Morse code without Manning ,the 250 foot long trailing wire
antenna used only for 500 kHz was removed in Florida to save weight. It
is possible that her radio might still have been able to put out a
significantly weakened signal of 500 kHz using the remaining antenna.
Noonan and AE most likely planned to use radio navigation for terminal
guidance as they approached Howland since radio navigation gets more
accurate as you approach the antenna while
celestial's accuracy remains
fixed. AE could have done any necessary radio work by herself so did not
need to carry Noonan all the way around the world if they had not
planned to use celestial, at least as a backup method for finding Howland.
When they were unable to get the radio signals they needed it is almost
certain that Noonan would have turned off to the left to intercept a sun
line LOP to the northwest of the island. From sunrise at about 1645 Z
(0615 Itasca time) and for more than and hour afterwards the azimuth of
the sun remained 067º T so the resulting LOP ran 157-337º T. Noonan
would have intercepted this LOP and followed it to Howland using the
"single LOP landfall procedure" popularized by Chichester as "deliberate
error" and also known as deliberate offset. This method had sufficient
accuracy to allow them to find Howland and was taught to all flight
navigators and was used
thousands of times successfully during WW 2 and
after to find small island destinations. In addition, the moon was also
visible and provided good cuts with the sun line to provide daylight
fixes.
AE's last transmission at 2013 Z (0843 Itasca Time) stated they were on
the 157º-337 ºLOP
More later.
gl
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