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    Re: lunar parallax killed Amelia Earhart
    From: Doug Royer
    Date: 2006 May 17, 17:25 -0700

    Here is the title and authors of the book I read about this. It's very good
    in technical and historical detail (although nothing is proved or
    finalized). It most likely is at your public library as that is where I
    picked it up.
    "Amelia Earhart: The Mystery Solved"
    Elgin and Marie Long
    Not going to argue about what you pointed out as I can't remember exactly
    what the book's author stated as ALL the celestial/navigational miscues that
    may have happened. But the gist of the book was of the combination of all
    the errors by all parties (especially the miscommunication about the radio
    frequencies to be used and the times to hail/use them by the plane, ships
    and shore station involved) lead to the failure. He did not bash Noonan's
    skills in the book. And Noonan did have a sextant onboard. At least before
    take off. He could have taken his cut/cuts out of the forward windows. There
    was mechanical trouble with the plane even before they got to the island
    (New Guinea?) and how well was it fixed or repaired? The plane was grossly
    overloaded with fuel and barely made it off the island at take off. Were the
    head winds grossly miscalculated? Thus putting them grossly out of position
    and/or consuming much more fuel than they calculated or allowed for.
    The book was written by a pilot who flew the guestimated track. It had chart
    diagrams of what he thought the plots of Noonan's LOPs looked like and he
    explained the "mistakes" in detail and the consequences of each mistake on
    the final outcome.
    It is interesting that the ships on station were able to receive some of
    Earhart's calls but couldn't communicate with her radio. And how well did
    her radio-direction finder really function? Was it calibrated and did she
    really understand how to use it?
    How clear was the atmosphere at altitude that morning when they did make the
    157/337 line turn to find the Island? Could they have even seen it if they
    were off by 25 miles from where they thought they were?
    No one heard any Mayday or distress calls from the plane even though they
    received other calls from her during at least 1 leg of the flight. Did she
    or they switch frequencies at the wrong time again?
    It is a very interesting story. I will find the title of the book and the
    author's name in the next few days and post it up.
    > This web page speculates that Amelia Earhart and Fred Noonan missed
    > Howland Island because Noonan failed to correct for parallax when he
    > shot the Moon:
    I believe Noonan precomputed his sight reductions (that's what I would
    do), so if he did make that mistake, it would have happened on the
    ground. A blunder that big seems unlikely, though.
    The 1939 edition of "Practical Air Navigation" (U.S. Department of
    Commerce publication) has a Moon altitude correction table. It's much
    like a modern table. You go down the left-hand column to find altitude,
    then move across until you come to the column corresponding to the
    Moon's parallax in altitude. The tabulated value at this point is the
    combined parallax, refraction, and semidiametor correction.
    This inventory of the plane's contents
    includes a 1937 Nautical Almanac near the bottom. I don't see sight
    reduction tables. Perhaps the
    "Navigation Tables for Mariners and Aviators" served that purpose. No
    sextant either. Maybe one of the navigators removed it.
    The FAQ at the TIGHAR site has some pages on the navigation techniques
    utilized on the flight:
    It says Fred Noonan had only one side window to make his celestial
    observations. That's almost unbelievable.
    Considerable space is devoted to explaining the meaning of the 157/337
    line Earhart mentioned in one of her last transmissions. According to
    the web site, it's a line of position obtained by noting the time of
    sunrise as they flew toward Howland Island. (The Sun would have risen on
    bearing 67? true; their inbound course was 77?.)
    What I don't understand is why Earhart and Noonan would advance this LOP
    and fly along it two hours later. A sunrise observation is the worst for
    refraction error. Add the error due to advancing the LOP, and it's not a
    pretty picture.
    If I were the navigator, I'd prepare a table of the Sun's altitude vs.
    time for Howland Island. Outbound from Lae, offset the course so the
    plane will definitely miss Howland to one side, say to the south. When
    my DR says we're on that Sun line, have Earhart turn left and put the
    Sun on our beam. Now it's conveniently positioned for observing through
    the side window. By comparing observed altitude to my table, I can see
    whether we're left or right of the LOP, in near real time. Staying on it
    should lead us to Howland. That's one of the standard airborne celestial
    techniques for making landfall on an island in the ocean.
    Noonan surely knew the method, but apparently didn't use it. I don't
    know why. Cloud cover doesn't seem to have been serious. Itasca's deck
    log says the sky was 3/10 obsured, and Earhart reported no trouble with
    The 157/337 line does make the lunar parallax theory less plausible. I
    can't see Earhart and Noonan running back and forth along the old
    sunrise LOP advanced to Howland Island if a newer LOP had been available.

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