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    Amelia Earhart navigation- basic information.
    From: Gary LaPook
    Date: 2009 Nov 28, 00:28 -0800

    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 078� 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 067� T so the resulting LOP ran 157-337� 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 157�-337 �LOP
    
    
    More later.
    
    gl
    
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