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    Re: Finally, a reasonable explanation for Earhart's failure to find Howland
    From: Gary LaPook
    Date: 2013 Feb 25, 22:05 -0800
    I also believe the two hundred mile estimate was DR.

    The plane had to start a descent from the cruising altitude down to 1,000 feet quite a distance prior to the estimated point of LOP interception to ensure that they did not miss the island by overshooting the LOP. A normal descent is 300 feet per nautical mile so the descent would take at least 30 NM plus an allowance to avoid an overshoot would mean they had to start a descent about 50 NM prior to the estimated interception point resulting in 5 NM DR uncertainty. If the sun sight was taken at 1822 Z they still had about 90 NM to the interception which would cause 9 NM in DR uncertainty

    https://tighar.org/smf/index.php/topic,696.msg15908.html#msg15908

    In addition to these DR uncertainties you have to add the possible error in the sun line of about 7 NM and additional possible errors due to the difference in the wind as determined at altitude and the most likely reduced wind speed at the lower altitudes.

    See:
    https://tighar.org/smf/index.php/topic,696.msg15908.html#msg15908

    gl

    --- On Sun, 2/24/13, Don Seltzer <timoneer@GMAIL.COM> wrote:

    From: Don Seltzer <timoneer@GMAIL.COM>
    Subject: [NavList 22479] Re: Finally, a reasonable explanation for Earhart's failure to find Howland
    To: garylapook@pacbell.net
    Date: Sunday, February 24, 2013, 9:53 AM


    Gary LaPook wrote:
    >I finally DO have an explanation for why Noonan was not able to find Howland, one that does not require any great error on his part. I am kicking myself that it took me so many years to see it.
    See it on my website at:

    https://sites.google.com/site/fredienoonan/a-valid-explanation-for-not-being-able-to-find-howland

    1415 Z overcast
    1515 Z overcast
    1623 Z partly cloudy
    1744 Z, wants bearing, about 200 miles out
    1815 Z take bearing on us and report in/on half hour will whistle in mic about 100 miles out
    1912 Z must be on you flying at 1,000 feet
    “CANNOT SEE U BUT GAS IS RUNNING LOW"
    "SEZ RUNNING OUT OF GAS ONLY 1/2 HOUR LEFT"
    1927 Z circling, go ahead now or on /in half hour
    1930 Z got your signal can’t get minimum
    2013 Z on the line 157-337 will repeat on 6210
    >

    Gary, thank you for this interesting post. I have a few questions regarding the last 200 miles of the flight.

    You wrote that the 1623Z report of some clearing suggests that Noonan took one or more celestial fixes at this time. SInce the 1744Z report of 200 miles out was in civil twilight, I assume that this was a dead reckoning estimate from his last celestial fix, sometime in the preceding hour and a half?

    The scenario has them altering course, aiming for the NW of Howland Island, hoping to intercept the 157-337 LOP shortly after sunrise. They are flying at 1000 feet, probably because of cloud cover. Under what set of conditions (cloud ceiling and time period) would Noonan have been able to get a good fix on the rising sun, to establish that they had reached the 157-337 line? If the cloud conditions prevented a proper sun observation, would he have still turned right based upon dead reckoning from his previous celestianl fix, perhaps three or even four hours earlier?

    Don Seltzer

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