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    Re: Amelia Earhart navigation- basic information.
    From: Gary LaPook
    Date: 2009 Nov 29, 03:52 -0800

    I need to correct a typo in my prior post. The sun rose at Howland at 
    0615 Itasca time, 1745 Z not the 1645 Z in my prior post.
    
    gl
    Gary LaPook wrote:
    > 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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