Hi everyone,
I've posted some new ideas about possible navigation errors due to the International Date Line on my website - www.datelinetheory.com. As far as I can tell, the Date Line has not been considered before as a direct cause for Earhart and Noonan becoming lost and/or not reaching Howland Island.
I'm very curious to hear what forum members have to say about my theory, given all of the experience and expertise of the group. I'd be grateful to hear any comments or thoughts on the matter. I propose the theory as one possible scenario, not necessarily the only scenario possible and I remain open to all the possibilities of what happened to the fliers until conclusive evidence of the Electra is found.
Thanks for your time,
Liz Smith
The Date Line Theory
www.datelinetheory.com
-------------------------------------------------------
I sent a series to Liz Smith pointing problems with suggestions but she never replied to me so I am not sure she got my emails. I am posting those comments here so that she may be able to get this information.
Gary LaPook
-------------------------------------------------------------
To Liz Smith
To summarize my prior messages. In the very unlikely event that Noonan erroneously used the data for July 3rd near the end of the flight for star sights he would have calculated a longitude about 59 NM west of his actual position which would then cause him to overshoot Howland. This is exactly the opposite of what your theory predicts.
I also pointed out that any longitude error from the star sights would be cured by the subsequent sun observation as the error from using the wrong day's data for sun sights is only 2.7 NM, not the 60 NM error that you theorized.
----------------------------------------------------------------------------
I read your website and it is quite interesting and I followed your computation but that is not the
way a navigator does it. We use Greenwich Hour Angle (GHA) to determine the positions of
bodies and this is directly tabulated in the Nautical Almanac and the Air Almanac for the sun,
planets and the moon. To determine the GHA of a star we find the GHA of Aries in the almanac
and add to it the Sidereal Hour Angle (SHA, the inverse of R.A.)
I an afraid that this is going to be embarrassing for you but you need to know about the errors in
your website. .
First, the date line is an imaginary line and you do not have to do anything when you cross it, you
can keep any date you want until you touch shore where it becomes convenient to get on the
same date they are using ashore. See the discussion at:
http://www.fer3.com/arc/m2.aspx?i=115629&y=201102You talk about "local time" but flight navigators have no use for local time. It is different on a
ship where the ship’s clock is changed by even hours at convenient points, when traveling east or
west, so that the ship's watches can be adjusted to keep in synch with the approximate local
apparent solar time and lunch can be served at approximately local noon. Time zones are 15
degrees wide, 900 NM at the equator, 450 NM at 60 degrees latitude. A ship sailing westward
near the equator at 12.5 knots will cover 900 NM, one time zone, every 72 hours so will set the
clock back one hour at noon every third day and this will keep the ship’s clock approximately in
step with the position of the sun. The same ship traveling westward at 60 degrees latitude will
reset the clock twice as frequently. In the days prior to time zones the ship’s time was reset to
noon each day at the noon observation. As Captain Aubrey said when looking through his
sextant, “Make it noon” and then the hour glass was turned and eight bells were sounded starting
the first afternoon watch.
Flight navigators do not reset their clocks while in flight so none of that applies to them. Almost
certainly Noonan kept his chronometers set to GMT. By his reckoning he took off at 0000 GMT
on July 2nd and planned to arrive at Howland at about 1800 GMT July 2nd and these would be the
times he used to look in his Nautical Almanac, not much chance for confusion here, no reason to
look at the next date’s data in the Nautical Almanac. Likewise on a ship, the ship’s chronometers
will be kept on GMT. However, the ship’s navigator doesn’t take the ship’s chronometer on deck
to time his celestial observations so he may set his wristwatch to local ship’s time by comparison
to the chronometer. He then uses the “Zone Description” (Z.D.) to convert his watch time to
GMT. (I am disregarding any watch error or chronometer error in this discussion but the
navigator will allow for them as part of the normal computation procedure. See the top of the
form at:
https://sites.google.com/site/fredienoonan/other-flight-navigation-information/modern-bygrave-slide-rule/NauticalAlmanacForm.pdf?attredirects=0 )
For the sake of argument, assume Noonan kept his watch on Lae time. The Zone Description at
Lae is minus ten hours (-10). This is the amount you must adjust your Lae watch time to find
GMT time and date. At the takeoff, Lae time was 1000 (10:00 a.m.) on July 2nd. Apply the -10
hour Zone Description by subtracting ten hours from Lae time and you find GMT of 0000 hours
and the date remains July 2nd. Eighteen hours later Lae time was 0400 (4:00 a.m.) July 3rd. and
you must subtract the same ten hours (since you have not changed your watch time, your watch is
still keeping Lae time, Z.D. is still -10.) Since you can’t subtract 10 from 4 you must borrow a
day, 24 hours, from July 3rd, and just like normal subtraction, when you borrow the day from July
3rd your reduce it by one day to July 2nd, You add the 24 hours to the time of 0400 making the
time 2800 (28:00) on July 2nd, and then subtract the ten hours (-10 Z.D.) and you still get 1800
GMT on July 2nd. This is the standard way navigators deal with time and Noonan had done this
same computation thousands of a times as a ship’s navigator. You can see how extremely
unlikely it would have been for Noonan to use the wrong date in the Nautical Almanac especially
since he almost certainly kept his chronometers set to GMT. It is also quite likely that Noonan
precomputed all of his landfall approach celestial data the night before they took off, or early in
the flight, for twenty minute intervals from 1800 GMT to 2400 GMT July 2nd so that he could
prepare a graph of the computed altitudes. See:
https://sites.google.com/site/fredienoonan/topics/precomputed-altitude-curvesTo do all of these computations and to draw the graph would take less than one hour. If you look
at his chart notations on the California to Hawaii and on the Natal to Dakar charts you will see
he marked the times of the LOPs in GMT but Earhart kept her journal on the time at the
departure point.
Assuming that he did use the wrong date then he would have had a longitude error of 59.1
minutes of longitude, 59.1 NM at the equator, for LOPs derived from taking observations of
STARS, so you are almost correct about this. You point out the discrepancy between the “200
mile” and the “100 mile” out position reports, claiming that crossing the dateline between these
observations caused Noonan to use the wrong date data accounting for the discrepancy. But,
Noonan would have noticed such a large discrepancy himself since there had to be an error
somewhere and he would have checked his computations. Such a large divergence in positions
would have required a 120 knot wind shift between the fixes which is obviously impossible.
Where you are completely wrong is in claiming that using the wrong date would cause the same
longitude error (60 NM) when shooting the sun for the LOPs for the landfall approach. See:
https://sites.google.com/site/fredienoonan/topics/landfall-procedureand: https://sites.google.com/site/fredienoonan/discussions/navigation-to-howland-island
All you have to do to see this is to look at the Nautical Almanac for July 2, 1937 which I posted
here:
https://sites.google.com/site/fredienoonan/resources/nautical-almanac-1937/almanac-1937-22.JPG?attredirects=0
Look at the Sun’s GHA (Greenwich Hour Angle) column, the third column, and compare the
values for the same times but for July 2nd and July 3rd. For example, at 1800 GMT on July 2nd the
sun’s GHA is 89̊ 02.5' and for the same time on July 3rd the GHA is 88̊ 59.6'. The difference
between these values is only 2.9' so if Noonan had used the GHA for July 3rd then the error in
longitude would have been only 2.9' which is 2.9 NM at the equator, not the 60 NM that you
claim. This slight difference is caused by the eccentricity of the earth’s orbit which causes its
orbital speed to vary resulting in solar days that are not exactly 24 hours long. This resulted in a
change in the equation of time between July 2nd and 3rd ,as can be seen by looking in the first
column in the almanac, from 3 minutes, 50.2 seconds to 4 minutes, 01.4 seconds and this 11
second change results in the 2.9' change in GHA and in the 2.9' error in longitude.
I think where you go wrong is in not recognizing the difference between GMT and Greenwich
Sidereal Time. A sidereal day is only 23 hours, 56 minutes and 4 seconds compared to the 24
hour solar day. This 3 minute and 56 seconds difference accounts for the 59.1' shift in the
positions of the stars but doesn’t effect the position of the sun for navigational purposes since its
position is determined by GMT not GST.
I have posted many reference documents that you might like to look at concerning the navigation
of this flight.
See:
https://sites.google.com/site/fredienoonan/--------------------------------------------------------------------------
If you look at the format of the 1937 almanac you will notice that both July 2nd and July 3rd are on the same page. So Noonan would be doing his computations and as the hours progressed he moves down the page through the July 2nd values. Then, as he crosses the date line and for his next sight he suddenly drops down to the next day giving up his orderly progress through the July 2nd data? I don't think so.
To be continued