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Author Topic: Why wasn't Gardiner identified in the radio messages?  (Read 167295 times)

Chuck Varney

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #60 on: December 15, 2011, 01:31:55 PM »

The Brandis sextants I've seen don't have any kind of "drum." The one I have here has a vernier and magnifier on the arc which is marked in 2° increments.

And the vernier permits interpolation to how small an angle?

Chuck
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Ric Gillespie

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #61 on: December 15, 2011, 01:34:26 PM »

And the vernier permits interpolation to how small an angle?

Beats me.
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Erik

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #62 on: December 15, 2011, 01:56:20 PM »

If we work it backwards, 279 miles is (as you've said) roughly 4.65°.  However, 281 miles works out to be 4.683°.  Obviously, this give us a difference of only 0.03°.  Not really familiar with the Brandis sextant, but my archaic old Esco (also marked in 2° increments) isn't even close to being capable of that kind of resolution based only on a simple sun shot. 

My only point is that a sun shot from Gardner with a Brandis sextant might reasonably result in an estimate of 281 nm from the equator.

So, wouldn't it depend on what part of the island would be 281?  Island is 4 miles long.  So 281 could be +/- 4 miles therby making a potential range 277-285 miles.  Depending on where the 281 is being calibrated.  If 281 is calculated in the south, then the north would be 277 miles away, and if calculated in the north then the south would be 285 miles away.

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John Ousterhout

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #63 on: December 15, 2011, 02:05:30 PM »

For an example of an older Sextant Vernier, see http://users.humboldt.edu/rpaselk/NavInst_Pics/VerSex_vern.jpg
It is a clear picture of the vernier scale on a high quality instrument for the 1900 period, and can be read to 10".  I would expect a much newer Brandis to be at least comparable, assuming it was about the same size.
However, I would also expect FN to use his Octant as his primary means to determine position, assuming it is a bit more accurate.  Besides, there seems no question that he at least had it on the aircraft.  What do we know about it? <answer: it was a US Navy Pioneer (aka "Brandis") Bubble Octant, #12-36, loaned by Harry Manning to FN, per his note dated March 20, 1937.  Similar "Aircraft Octants" in the Smithsonian collection have boxes essentially identical to "Sextant" boxes, but quite different from the Octant box picture posted earlier by Ric.  His Octant box looks much like the one I've got at home, and which is much newer than 1937.>
<edit: http://americanhistory.si.edu/collections/navigation/object.cfm?recordnumber=451575 is a photo of a 1920 Brandis, perhaps a bit more like FN's instrument.  It's scale is "read...to 30" seconds of arc">
Cheers,
JohnO
 
« Last Edit: December 15, 2011, 03:54:26 PM by John Ousterhout »
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Gary LaPook

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #64 on: December 15, 2011, 03:53:17 PM »

If we work it backwards, 279 miles is (as you've said) roughly 4.65°.  However, 281 miles works out to be 4.683°.  Obviously, this give us a difference of only 0.03°.  Not really familiar with the Brandis sextant, but my archaic old Esco (also marked in 2° increments) isn't even close to being capable of that kind of resolution based only on a simple sun shot. 

My only point is that a sun shot from Gardner with a Brandis sextant might reasonably result in an estimate of 281 nm from the equator.

So, wouldn't it depend on what part of the island would be 281?  Island is 4 miles long.  So 281 could be +/- 4 miles therby making a potential range 277-285 miles.  Depending on where the 281 is being calibrated.  If 281 is calculated in the south, then the north would be 277 miles away, and if calculated in the north then the south would be 285 miles away.

The island is that size from roughly NW to SE, but not N to S (maybe half).

"281" miles south of equator = latitude running through Aukermaine area of island - 'dry' land.  The place where some artifacts were found happens to lie there - shoe parts.   

LTM -
I'll help you guys out with this. Celestial navigation is based on the assumption that one degree along any great circle on earth is exactly 60 nautical miles. Meridians are great circles so latitude, which is measured north or south along a meridian, is also measured in degrees that are exactly 60 nautical miles long. Since the earth is not a perfect sphere, a degree along a great circle is not exactly 60 nautical miles depending where you on the earth, but to the precision available with celestial navigation you can't tell the difference. (This is not true, of course, when it comes to longitude since parallels of latitude are not great circles but get smaller the closer you come to either pole. The exception is that the equator which is a great circle.)

According to Google Earth, the latitude at the very northern tip of Gardner is 4° 39.3' south. (I have checked the accuracy of the coordinates shown by Google Earth in this area by comparison to the published coordinates of airports and they are very accurate.)
So four degrees times 60 NM per degree equals 240 NM. Add to this the 39.3 NM from the extra minutes of latitude (one minute of latitude equals one nautical mile) makes the distance from the equator equal 279.3 NM as calculated by celestial navigation.
For the other extreme we find a latitude of 4° 41.5' south, 281.5 NM from the equator. This point is near the eastern tip of the island but where they could still observe noon straight north of them over a sea horizon as would be necessary if they were using a marine sextant. If using the Pioneer octant then they could measure noon at the southern tip of the island at latitude 4° 41.8' south, 281.8 NM from the equator. The published coordinates for Gardner in current navigation reference books is 4° 40' south.

gl
« Last Edit: December 15, 2011, 03:56:33 PM by Gary LaPook »
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Gary LaPook

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #65 on: December 15, 2011, 04:51:55 PM »

Quote from GL -

Through WW2 celestial navigation was the only method of long range, oceanic navigation. Towards the very end of the war, LORAN-A came on line and was installed in some planes. For example, the B-17 carrying Rickenbacker (a very big VIP on a high priority mission) only had celestial navigation for navigation and had only one octant on board and this was five years after Earhart disappeared."


I think your explanation of Rickenbacker's "fix" underscores the point: a "preventer" isn't a bad idea, now is it?  Just curious, but what have WWII and later developments have to do with AE's fix in 1937? We're kind of stuck with what she was stuck with.


We call this "custom and practice in the industry" and a widespread practice in an industry is admissible to prove something happened or was done on a particular occasion. The flying industry, from before Noonan's time until quite lately, had a practice of carrying only one octant on a plane so this tends to prove that Noonan did not carry two sextants on the Earhart flight. ( It was also "custom and practice" that only one sextant was carried on ships too.) Of course, if you can come up with a photo or a witness statement saying that Noonan carried a mariner's sextant on the Earhart flight, or that he always carried a marine sextant duct taped to his stomach (he told me "you never know when you might need one"), then you win, you've proved your point. The letter to Weems doesn't even come close and would not even be admissible into evidence because it is too remote and the situation is too different so it cannot be used to show a "habit" of Noonan's. There is a reason we have rules of evidence to keep this type of thing from being shown to a jury, and I am not just talking about in criminal cases where the burden of proof is "beyond a reasonable doubt" but also in civil trials with a much lower burden of proof of "more probable than not." The reason that this would not be admissible is that the people in the jury might make unwarranted and unreasonable inferences from it (kinda like you guys, I rest my case. ;)) And this is in a jury trial where the jurors are impartial and do not have a dog in the fight. Those who believe in the Gardner theory are not impartial, they believe that the sextant box found on the island supports their theory that the plane landed there so to help their theory Noonan had to have had that marine sextant in the Electra. This subtly affects their thinking regarding  whether the marine sextant was on the flight. They are engaging in "circular reasoning." Earhart landed on Gardner so this sextant box came from them. Since this sextant box came from them then they must have had it in the Electra. Since they had the sextant box in the Electra and we found it on Gardner then we have proved that the landed on Gardner. We can go around the circle again if you like. This is classical "circular reasoning." For the box on Gardner to lend support to your theory you must prove by evidence independent of the box on Gardner that Noonan carried it in the Electra and nobody has been able to show that, only speculation and unsupported inferences  from an inadmisable letter.
I could still be convinced, but it is your theory that they landed on Gardner and I am only keeping you honest, asking you to prove it.

gl
« Last Edit: December 15, 2011, 04:54:09 PM by Gary LaPook »
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Harry Howe, Jr.

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #66 on: December 15, 2011, 05:51:06 PM »


Gary
What bothers me is: If they measured their latitude and found it to be 4degrees41minutes S why wouldn't they just transmit it as such?  Why go thru the trouble of converting it to 281 miles N?
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Gary LaPook

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #67 on: December 15, 2011, 05:55:32 PM »


Gary
What bothers me is: If they measured their latitude and found it to be 4degrees41minutes S why wouldn't they just transmit it as such?  Why go thru the trouble of converting it to 281 miles N?
I already pointed that out.

gl
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Erik

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #68 on: December 15, 2011, 05:57:32 PM »

Let's remember the topic at hand - "Why wasn't Gardiner identified in the radio messages?"

For purposes of this discussion, it doesn't matter a whole lot the precision in which we can measure 281 miles.  Or even the exact length of Gardner diagonal or otherwise.   In other words, anything close to 281, would certainly define where they were within enough accuracy to identify the island they were on.  If they were floating in a featureless ocean, then things would be much different story.  Keep in mind the difference between precision and accuracy for the purposes of this discussion.

When it comes to tic' marks on the sextant (or any other device) it wouldn't matter too much about the precision of the 2° arc minutes.  Anything close would serve the purpose of identifying the island's location.  A degree of longitude for all practial purposes is 60nm anywhere within a 500 mile buffer of the equator.  You'd have to be 10-20 degrees off of the equator before you saw any noticeable deviation from 60nm rule of thumb - at least for this discussion's purposes.  As Gary points out, lattitude is not affected by this, making the North-South measurements somewhat even less affected by accuratlely measuring distances on the curved surface of the earth. 

I do find it fascinating that the 281 mark is right on for the Aukermaine site.  Perhaps in hindsight it would matter the precision in which they were identifying their location on the island.  That would be extremely insightful for them to radio their actual rescue location as opposed the aircraft's transmitting location.  That's where the argument of the 2° tic marks would actually have some significance.  Unless of course they originally landed at Aukermine, transmitting from there, and nessie was their 2nd landing location!  Stealing from a previous thread' - cue the spooky music! .........
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Erik

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #69 on: December 15, 2011, 06:09:15 PM »


Gary
What bothers me is: If they measured their latitude and found it to be 4degrees41minutes S why wouldn't they just transmit it as such?  Why go thru the trouble of converting it to 281 miles N?

One of the radio transmission did point out the lat long of their locaiton.  This discussion is focused on the 281 transmision for some reason.  The transmision that did identify the lat long was remarkbly close to Garnder if you consider for a moment that the sextant was broken, lost, or otherwise non-functioning.  Even using your finger strected at arms-length is a very crude way of measuring one degree of angular distance.  If I recall correctly the radio transmission that had the lat long coordinate was within 20-30 miles of Gardner.  Reasonable accuracy if all you have is your finger!  Not trying to be funny, but rather morbidly realistic given undetermined circumstances.   ???
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Harry Howe, Jr.

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #70 on: December 15, 2011, 06:16:47 PM »


Gary
What bothers me is: If they measured their latitude and found it to be 4degrees41minutes S why wouldn't they just transmit it as such?  Why go thru the trouble of converting it to 281 miles N?
I already pointed that out.

Great minds running on the same tracks.

gl
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Gary LaPook

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #71 on: December 15, 2011, 06:35:06 PM »


Gary
What bothers me is: If they measured their latitude and found it to be 4degrees41minutes S why wouldn't they just transmit it as such?  Why go thru the trouble of converting it to 281 miles N?

One of the radio transmission did point out the lat long of their locaiton.  This discussion is focused on the 281 transmision for some reason.  The transmision that did identify the lat long was remarkbly close to Garnder if you consider for a moment that the sextant was broken, lost, or otherwise non-functioning.  Even using your finger strected at arms-length is a very crude way of measuring one degree of angular distance.  If I recall correctly the radio transmission that had the lat long coordinate was within 20-30 miles of Gardner.  Reasonable accuracy if all you have is your finger!  Not trying to be funny, but rather morbidly realistic given undetermined circumstances.   ???
This is news to me! Can you point us to that transmission?

gl
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Ricker H Jones

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #72 on: December 15, 2011, 06:41:59 PM »



 From GL:  'The flying industry, from before Noonan's time until quite lately, had a practice of carrying only one octant on a plane so this tends to prove that Noonan did not carry two sextants on the Earhart flight.'
 
It wasn't cut and dried.  For example, the B-47 did carry two sextants.  One used by the Navigator-Bombarier in the nose, the other by the copilot in the rear tandem seat behind the pilot.  During the first World Flight attempt I thought it odd that Harry Manning had to arrange to borrow the Pioneer octant (36-12) from the North Island Naval Air Station in San Diego just a day before the Electra departed.  Even poor planning could not account for failure to provide for a sextant.  My belief is that an additional sextant (the term sextant is used generically to include sextants, octants, quadrants, etc.) was wanted aboard the Electra with the late addition of a second navigator--Noonan shooting from the copilot's seat, and Manning from the cabin to eliminate "musical chairs", or passing one sextant back and forth.  It wouldn't surprise me if a third sextant (the "preventer") was aboard, too.  Of course, this sheds little light on what was done on the second attempt.
By the way, the Luke Field inventory did list two drift sights.  The Pelorus drift sight is the one we see in the picture by the nav table (picture below).  The D-270 speed and drift indicator listed  may be the Pioneer drift sight that is described in the New York Herald Tribune article quoted in My Courageous Sister, but I have not seen a picture or description of it.
 
107
1
Ea.Speed & drift indicator, type D-270, with handbook
122
1
Pelorus drift sight, MK II B with extra base
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Erik

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #73 on: December 15, 2011, 06:57:01 PM »


Gary
What bothers me is: If they measured their latitude and found it to be 4degrees41minutes S why wouldn't they just transmit it as such?  Why go thru the trouble of converting it to 281 miles N?

One of the radio transmission did point out the lat long of their locaiton.  This discussion is focused on the 281 transmision for some reason.  The transmision that did identify the lat long was remarkbly close to Garnder if you consider for a moment that the sextant was broken, lost, or otherwise non-functioning.  Even using your finger strected at arms-length is a very crude way of measuring one degree of angular distance.  If I recall correctly the radio transmission that had the lat long coordinate was within 20-30 miles of Gardner.  Reasonable accuracy if all you have is your finger!  Not trying to be funny, but rather morbidly realistic given undetermined circumstances.   ???
This is news to me! Can you point us to that transmission?

gl


http://news.google.com/newspapers?id=pVIfAAAAIBAJ&sjid=J9IEAAAAIBAJ&pg=2178%2C945762
  • The lattitude was within 20 miles.  Not bad measuring angular distances if all you have is your finger.
  • The longitude was within 90 miles.  Not bad either considering the timing errors introduced for calculating longitude if all you have is a wristwatch, the sun, and a horizon.
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Gary LaPook

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Re: Why wasn't Gardiner identified in the radio messages?
« Reply #74 on: December 15, 2011, 07:08:58 PM »


Gary
What bothers me is: If they measured their latitude and found it to be 4degrees41minutes S why wouldn't they just transmit it as such?  Why go thru the trouble of converting it to 281 miles N?


One of the radio transmission did point out the lat long of their locaiton.  This discussion is focused on the 281 transmision for some reason.  The transmision that did identify the lat long was remarkbly close to Garnder if you consider for a moment that the sextant was broken, lost, or otherwise non-functioning.  Even using your finger strected at arms-length is a very crude way of measuring one degree of angular distance.  If I recall correctly the radio transmission that had the lat long coordinate was within 20-30 miles of Gardner.  Reasonable accuracy if all you have is your finger!  Not trying to be funny, but rather morbidly realistic given undetermined circumstances.   ???
This is news to me! Can you point us to that transmission?

gl


http://news.google.com/newspapers?id=pVIfAAAAIBAJ&sjid=J9IEAAAAIBAJ&pg=2178%2C945762
  • The lattitude was within 20 miles.  Not bad measuring angular distances if all you have is your finger.
  • The longitude was within 90 miles.  Not bad either considering the timing errors introduced for calculating longitude if all you have is a wristwatch, the sun, and a horizon.
Well that's interesting. Of course that position is a whole lot closer to Hull island than it is to Gardner. Is this included in TIGHAR's list of all radio messages?

gl
« Last Edit: December 15, 2011, 11:56:21 PM by Gary LaPook »
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