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JNev

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Re: What happened with the moon
« Reply #15 on: September 28, 2013, 10:09:27 AM »

"...Unless of course a 5 NM margin really was the tragic difference somehow - not likely so far as I can tell."
In a different thread I discovered that an aircraft similar to the Lockheed 10 became impossible to hear at a distance significantly less than 5 miles.  If Amelia had flown within visual distance of Howland, she would not yet been within hearing distance.  By the same token, she wouldn't have heard a search aircraft overhead until it was within about 60 seconds of arrival.

It seems like Gary LaPook shared some observations made from his home regarding similar aircraft / similar powerplants and from how far away he could discern the engine sounds.  Something like 5 miles sounds about right, if my memory is that good.  I'm sure it can be found in the annals here.

That seems reasonable enough to me.  I live in a rural area and occasionally we have a radial-engined airplane pass on a nice day - at times a DC-3, have seen a twin Beech a few times.  Dusters around here mostly use turbines these days - different prospect.  I don't know the mileage for sure - but I believe an approaching twin with radials 'gets my attention' from a couple to 3 miles away, time enough to get to the yard and spot it, if in view.  Then by another minute or two it has typically faded into the distance.

I don't know the facts of it, of course - but my belief is that if Earhart got within 5 miles - or even 10 miles, even puny Howland might well have been spotted - even the Itasca.  Have a look at the Nauticos site and see what they saw - yes, it can be tough - and I think I can see where a 20 mile or more 'miss' could easily make spotting the island very hard on the wrong day.  But 5 or 10 miles?  I have my doubts, IMHO of course, YMMV.
- Jeff Neville

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John Ousterhout

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Re: What happened with the moon
« Reply #16 on: September 28, 2013, 10:59:44 AM »

Here's some general information of the sun and moon in the vicinity of Howland island.  (I picked GMT -11 hours, so don't confuse the 11.5 hour time used by Itasca) The moon had risen about 5 hours before sunrise, so it would have been almost directly overhead at sunrise, or a bit less than 90 degrees from the sun.  For clouds to obscure the moon at that time, they would need to be overhead and/or a solid overcast that couldn't be climbed above.  Note that the cockpit was the best place for Fred to "shoot the moon" ( ;)) at such a high elevation.
(from US Naval Observatory web site)
The following information is provided for Howland Island (longitude W176.6, latitude N0.8):

        Friday   
        2 July 1937           Universal Time - 11h           

                         SUN
        Begin civil twilight      06:23                 
        Sunrise                   06:45                 
        Sun transit               12:50                 
        Sunset                    18:55                 
        End civil twilight        19:18                 

                         MOON
        Moonset                   12:58 on preceding day
        Moonrise                  01:24                 
        Moon transit              07:37                 
        Moonset                   13:51                 
        Moonrise                  02:18 on following day

 
Phase of the Moon on 2 July:   waning crescent with 34% of the Moon's visible disk illuminated.
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JNev

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Re: What happened with the moon
« Reply #17 on: September 29, 2013, 07:59:55 AM »

Here's some general information of the sun and moon in the vicinity of Howland island.  (I picked GMT -11 hours, so don't confuse the 11.5 hour time used by Itasca) The moon had risen about 5 hours before sunrise, so it would have been almost directly overhead at sunrise, or a bit less than 90 degrees from the sun.  For clouds to obscure the moon at that time, they would need to be overhead and/or a solid overcast that couldn't be climbed above. Note that the cockpit was the best place for Fred to "shoot the moon" ( ;)) at such a high elevation.
(from US Naval Observatory web site)
...

Phase of the Moon on 2 July:   waning crescent with 34% of the Moon's visible disk illuminated.

Precisely.
- Jeff Neville

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Harry Howe, Jr.

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Re: What happened with the moon
« Reply #18 on: September 29, 2013, 10:50:37 AM »

If FN did not get a fix on the moon while they were flying towards Howland on the LOP 157/337, how did AE know she was 100 miles out when she made that radio report to the Itasca?  That report "100 miles out" makes no snse to me because it is 1/2 hour after she reported that she was 200 miles out.  Did she get "get home itis" and crank her speed to the max (200mph, 100 miles in 1/2 hour)?  Not likely, considering a potential fuel shortage.  Conclusion:they weren't 200 miles out at the time she reported that she reported that, they reached that point earlier but she didn't report it until her standard transmittal time of 15 past the hour and the half-hour.  She was a terrible communicator at a time when the accurate communication of information was critical!  And it cost them their lives.
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Harry Howe, Jr.

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Re: What happened with the moon
« Reply #19 on: September 29, 2013, 11:14:41 AM »

Around the time of the flight there were charts having Howland mislocated 5 nm to the west of its "true" location.  We don't know what charts FN used in planning the Lae to Howland Leg.  We are expected to believe that FN, perhaps the most expert over-water navigator in the world, planned to fly the reverse of a complex 16 point great circle route plotted out by some other navigator for some other flight.  Nonsense.

If, when they arrived in the vicinity of Howland and were on the edge of their visiblity circle, that 5 nm error was critical.  We don't know which chart FN used to plan the Leg, he didn't leave it behind.
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JNev

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Re: What happened with the moon
« Reply #20 on: September 29, 2013, 03:05:34 PM »

If FN did not get a fix on the moon while they were flying towards Howland on the LOP 157/337, how did AE know she was 100 miles out when she made that radio report to the Itasca?  That report "100 miles out" makes no snse to me because it is 1/2 hour after she reported that she was 200 miles out.  Did she get "get home itis" and crank her speed to the max (200mph, 100 miles in 1/2 hour)?  Not likely, considering a potential fuel shortage.  Conclusion:they weren't 200 miles out at the time she reported that she reported that, they reached that point earlier but she didn't report it until her standard transmittal time of 15 past the hour and the half-hour.  She was a terrible communicator at a time when the accurate communication of information was critical!  And it cost them their lives.

If memory serves (highly suspect) the thought was that Earhart believed she was first 200 miles out for some reason, (perhaps due to DR/time elapsed?) then the call of "100 miles out" came - and to me at least suggests revised navigational information. 

I don't recall that it was "100 miles out - ALONG the LOP", but thought to be "100 miles from Howland".  Then, when Howland did not appear as expected, she would then be 'flying the line of position' to look north, then southward for Howland along that line, at least as some of us tend to see it.

To me, the two calls - 200 miles, then 100 miles - the second call made in too little time after the first to have covered the difference of 100 miles - suggests a couple of things: she may have had a delay in her "200 mile" report transmission and had already covered some of the difference, or - perhaps she had revised position information suggesting she was closer to Howland than she first thought.

The second (revised information) seems more ominous to me - was the new "100 miles out" position reliably revised, e.g. by a celestial shot?  Or by some less reliable method?  Either way, I've never been able to get past the suggestion in those things that for some reason she was confused as to how far east-west she was at those points.  Of course we don't know that she didn't find the desired LOP, but I have long held a thought that she may well have, and by some many miles due to this possible confusion - whatever would have caused it.

The moon might have been useful as to how far north or south along the LOP, yes.  They were dependent on celestial sunrise shot for LOP offset, or failing that, DR / time elapsed.
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JNev

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Re: What happened with the moon
« Reply #21 on: September 29, 2013, 03:23:52 PM »

Around the time of the flight there were charts having Howland mislocated 5 nm to the west of its "true" location.  We don't know what charts FN used in planning the Lae to Howland Leg.  We are expected to believe that FN, perhaps the most expert over-water navigator in the world, planned to fly the reverse of a complex 16 point great circle route plotted out by some other navigator for some other flight.  Nonsense.

If, when they arrived in the vicinity of Howland and were on the edge of their visiblity circle, that 5 nm error was critical.  We don't know which chart FN used to plan the Leg, he didn't leave it behind.

No we don't, and as has been pointed out Noonan really didn't have to over-labor on a great circle set of heading changes for this near-equatorial flight, either.  A rhumb line across a Mercator chart would have done it as well.

Clarence Williams had done the original charting for east to west and did use a great circle projection - very elaborate.

It seems to me that the most critical part of the 5 mile error would have been the resulting 5 mile offset - at worst, Noonan would have been looking for Howland 5 miles sooner than truly would be the case.  While that does not seem earth shattering, I can see, for example, that if their estimated LOP arrivale point was actually about 20 miles too soon (too far west) - AND one adds another 5 miles, now the flight could be just outside of the fringe of visual range (for instance - YMMV, of course).  I can further see how that might have put them flying up and down a badly estimated LOP that could have been tragically offset some 25 miles too far west - which I don't think would preclude what TIGHAR has postulated for the Gardner landfall (but other's MMV, of course).

But that makes the basic question loom larger - WHY?  Was there some reason that reliable celestial nav fixes were not being taken?  Now we've throw a hypothetical E-W error due to perhaps a lack of a good sun-shot at dawn (or perhaps unforeseen DR errors AFTER the sunrise LOP offset was taken) on top of the possible N-S error resulting from 'no moon shot'.

I don't know that we'll ever know if the 5 mile error figured into the loss or not - but it is an interesting thought.
- Jeff Neville

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JNev

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Re: What happened with the moon
« Reply #22 on: September 30, 2013, 04:49:30 PM »

"200 miles out" vs. "100 miles out" -

I stand corrected on this point - a review of the Itasca's radio logs is revealing - look at the entries at 0614 and 0615, then 0646 -

0614 "Wants bearing on 3105 KCS  on hour  will whistle in mic"
0615 "About two hundred miles out  appx   whistling nw (now)"

That is the "200 mile" call.

Then -

0645 "Pse (please) take bearing on us and report in half hour"
0646 "I will make noise in mic abt (about) 100 miles out"

That is NOT "the 100 mile call" - it is a "will" (future tense) statement.

Therefore IMO the radio log does not support Earhart having 'covered 100 miles in a half-hour' -

Note the distinction in the language in the two calls - it appears significant:
- At 0614/0615 she reports at "about 200 miles out" and whistles for recognition.
- At 0645.0646 she asks for a bearing to be taken on her and reported in half-hour; also says "will make" noise in mic "about 100 miles out" -

No noise came to mark the 100 mile point, although there were subsequent calls; but we're never really informed as to what point in time put Earhart "100 miles out" by hers or Fred's estimate.

I suspect this distinction has been well covered before, but somehow I'd overlooked it until now, if so.

In any case, it still does not appear to relate to how far from Howland 'along the LOP' - but probably from Howland along the route of flight, or perhaps distance from what they hoped was Howland, AND where the LOP would lie.  That could include a deliberate offset, if that technique was being used (we don't know).

If FN did not get a fix on the moon while they were flying towards Howland on the LOP 157/337, how did AE know she was 100 miles out when she made that radio report to the Itasca?  That report "100 miles out" makes no snse to me because it is 1/2 hour after she reported that she was 200 miles out.  Did she get "get home itis" and crank her speed to the max (200mph, 100 miles in 1/2 hour)?  Not likely, considering a potential fuel shortage.  Conclusion:they weren't 200 miles out at the time she reported that she reported that, they reached that point earlier but she didn't report it until her standard transmittal time of 15 past the hour and the half-hour.  She was a terrible communicator at a time when the accurate communication of information was critical!  And it cost them their lives.

If memory serves (highly suspect) the thought was that Earhart believed she was first 200 miles out for some reason, (perhaps due to DR/time elapsed?) then the call of "100 miles out" came - and to me at least suggests revised navigational information (corrected - see above). 

I don't recall that it was "100 miles out - ALONG the LOP", but thought to be "100 miles from Howland" (and per above the "100 miles out" call never really came).  Then, when Howland did not appear as expected, she would then be 'flying the line of position' to look north, then southward for Howland along that line, at least as some of us tend to see it.

To me, the two calls - 200 miles, then 100 miles - the second call made in too little time after the first to have covered the difference of 100 miles - suggests a couple of things: she may have had a delay in her "200 mile" report transmission and had already covered some of the difference, or - perhaps she had revised position information suggesting she was closer to Howland than she first thought. (See above - more likely 'made the 200 mile out call', but never did alert Itasca as to '100 miles out'.)

The second (revised information) seems more ominous to me - was the new "100 miles out" position reliably revised, e.g. by a celestial shot?  Or by some less reliable method?  (See above - we have no idea at what time Earhart believed she was '100 miles out' - she may have known but it was not reported.)  Either way, I've never been able to get past the suggestion in those things that for some reason she was confused as to how far east-west she was at those points.  (I still believe that may have been the case.)  Of course we don't know that she didn't find the desired LOP, but I have long held a thought that she may well have, and by some many miles due to this possible confusion - whatever would have caused it.

The moon might have been useful as to how far north or south along the LOP, yes.  They were dependent on celestial sunrise shot for LOP offset, or failing that, DR / time elapsed.
- Jeff Neville

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« Last Edit: September 30, 2013, 04:51:22 PM by Jeff Neville »
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Martin X. Moleski, SJ

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Re: What happened with the moon
« Reply #23 on: September 30, 2013, 06:17:31 PM »

0646 "I will make noise in mic abt (about) 100 miles out"

That is NOT "the 100 mile call" - it is a "will" (future tense) statement.

This is a classic punctuation problem.

The transmission timeline that I use reads like this:

Itasca1 states: "Earhart on nw reception fairly clr nw Wants bearing es [and] wnts rept in 1/2/ hr"; Bellarts states: "Pse [please] take bearing on us and report in half hour--I will make noise [sic] in mic - abt 100 miles out";[3] Howland Island reports: "(am using the D/F and receiving set sparingly due to heavy drainage on batteries) (the batteries are of low AM-Hour capacity) Earhart on the air, S4 [signal strength 4], "give me a bearing" Earhart did not test for bearing. Her transmission too short for bearing, static x5, her carrier is completely modulated. Could not get a bearing due to above reasons. 3105." Itasca bridge log states: "Miss Earhart reported position 100 miles from island reception fair."
LTM,

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Ted G Campbell

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Re: What happened with the moon
« Reply #24 on: October 06, 2013, 08:32:47 PM »

Way to compecated for us simple minds.  What is your point?
Ted Campbell
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C.W. Herndon

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Re: What happened with the moon
« Reply #25 on: October 14, 2013, 09:19:04 AM »

Do we have weather logs from Itasca/Howland  or anyone else in the vicinity for the 48 hours after Earhart's disappearance?

Neff, that information is found here. This is a fairly large file so it might take a little while to download, depending on your computer.
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JNev

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Re: What happened with the moon
« Reply #26 on: October 24, 2013, 09:56:37 AM »

Do we have weather logs from Itasca/Howland  or anyone else in the vicinity for the 48 hours after Earhart's disappearance?

Neff, that information is found here. This is a fairly large file so it might take a little while to download, depending on your computer.

From the deck log prior to movement from Howland it appears clouds in area were (times local so far as I can tell) -

4 a.m.     a.cu (alto-cumulus) - coverage 2/10's - vis 8
5 a.m.     cu (cumulus) - 2/10's - vis 9
6 a.m.     s.cu (strato-cumulus) - 4/10's - vis 9 ("a.cu" could suggest some overcast, but report was only 4/10's so more than half of sky open in area)
7 a.m.     cu - 3/10's - vis 9
8 a.m.     cu - 3/10's - vis 9
9 a.m.     cu - 2/10's - vis 9
10 a.m.   cu - 3/10's - vis 9

After underway -

11 a.m. - total run 10.2 NM - HDG 337 - s.cu - 5/10's - vis 9
12 p.m. - total run 24.8 NM - last hour 14.6 NM on HDG 338 - cu - 5/10's - vis 9
1 p.m. -   40.8 NM - HDG 338 - a.cu - 6/10's (here "bc" changes to "c" - "sky mainly cloudy" - vis 9 
2 p.m. -   55.8 NM - last hour 15.0 NM on HDG 080 - cu 5/10's (back to "bc" conditions) - vis 9
3 p.m. -   70.4 NM - HDG 080 - cu 3/10's - vis 9
4 p.m. -   85.0 NM - HDG 080 - cu 4/10's - vis 9
5 p.m. -   99.6 NM - HDG 080 - ci.cu 5/10's (cirrus-cu) - vis 9
6 p.m. -   114.2 NM - HDG 080 - a.cu 5/10's - vis 9
7 p.m. -   128.8 NM - last hour 14.6 NM on HDG 345 - a.cu 10/10's ("o" conditions - overcast) - vis 8
8 p.m. -   143.4 NM - last hour 14.6 NM on HDG 080 - a.s (alto-strat?) 8/10's - vis 8
9 p.m. -   158.0 NM - last hour 14.6 NM on HDG 312 - a.s 6/10's - vis 8
10 p.m. -  172.6 NM - last hour 14.6 NM on HDG 338 - a.cu 2/10's - vis 8

Thence back on HDG 212 -
11 p.m. - 185.5 NM - last hour 12.9 NM on HDG 212 - cu 2/10's - vis 8
12 p.m. -  197.1 NM - last hour 11.6 NM on HDG 212 - cu 2/10's - vis 8

(Edited by JN - redid the rough math and added some comments on Thompson's direction that morning) -

Thompson seems to have found himself under heavier skies around 50+ 60+ NM north / northwest north-northeast of Howland - which appears to the area he concentrated on as probable for a crash at sea for his own reasons.  Those appear to include That does not preclude the afore-referenced (in my earlier post, above) mention of substantial clouds to NW of Howland as observed by Itasca in the Cruise Report.  For whatever reason, Thompson seems to have thought the clouds he could see may have played a role in the flight's failure to get workable celestial shots that might have brought them closer; he also seems to believe the flight had progressed further to the east than I had understood before (I believe he mentions that in the report or deck log perhaps).

That same Cruise Report noted 'stellar conditions' for celestial naviation to SE of Howland throughout the night before, and no heavy skies noted in that sector as to the day's observations.  Flying conditions at / immediately around Howland were said to be excellent.  Perhaps that contrast in conditions led Thompson away from the south / southeast as a probability that morning - IMHO, YMMV, of course.

This seems to suggest that there was no huge area of overcast all around Itasca, but some conditions approaching and briefly reaching overcast conditions were encountered to the NNW north and north-northeast during Itasca's search.  Couple that with the Cruise Report comment on large cloud formations to NW of Howland and the notion of Howland being on the SE edge - and some distance from - possible overcast (or at least observably cloudy) conditions to the NW.  My take-away is that Thompson viewed the significant cloud formations in the distance as possibly interfering with celestial navigation (perhaps saw formations suggestive of overcast above the flight's likely altitude).  He certainly realized the flight had failed at any meaningful radio direction finding - all said, I believe, in his report or the deck log.

If anywhere nearer Howland than 40 miles to west / NW / north it seems the flight should have had decent celestial nav conditions.

The same for an observable distance ('vis 9') from Itasca to SE of Howland, according to the report.

To me that mystery remains - what was Fred doing, and where was the moon?

Some things do make me want to reconsider the Benedictine bottle found on Gardner... oh, that's nasty - I'm getting too bored now.

In any case, given what Thompson had for information at the time, I can see why he went where he did.  Later reports of post-loss signals and analysis of Noonan's 'likely actions' led to a different tack by Friedell, as we know.

IMHO, Itasca had little chance of spotting the wreck on the sea that day, had it been there - for what that is worth: one slow little ship making its best effort to cover a speculated area of the flight's end. 

I will jump threads slightly and say that similarly, the Colorado's attempt among the Phoenix Group, as Ric Gillespie recently pointed out, can hardly be considered conclusive either - what began as an educated guess by an able navy officer based on some fairly extensive briefings that Thompson did not have earlier soon ended with near administrative brutality - 'we looked real good down there - go elsewhere'.  I'm not sure that Thompson's idea really got any better respect either in 1937 - just MHO, and I have the feeling that the biggest show in the Pacific at the time - the Lexington Group - did an exemplary job of covering a lot of ocean with near zero potential for yielding the wreck.

Anyway, back on track - where was the moon in all this?  Conditions don't seem to have been bad enough any where near Howland - even considering that chunk of heavy sky Thompson managed to steam under to the NNE, to preclude a shot.  Celestial conditions certainly seem to have been even better to the south-southeast, at least by what Itasca could see at vis 9 from Howland.
- Jeff Neville

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« Last Edit: October 25, 2013, 01:52:50 PM by Jeff Nevil »
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JNev

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Re: What happened with the moon
« Reply #27 on: October 29, 2013, 08:21:16 AM »

Point: Between 6:45 and 8:45 it should have been easy for Noonan to get a good fix on his position assuming he could see both the sun and moon within a short period of time or even a fair fix assuming he saw them at disparate times and had to advance one LOP. 

The fact Earhart only gave a solar LOP suggest Noonan was only able to see the sun.

The LOP it's self suggest either a sunrise LOP perhaps nothing more than  Noonan's best guess of when the overcast lightened, or a sight between 6:18 and 7:18.

All facts consistent with but not proving Noonan was under an overcast the entire period.

Interesting.

If under the overcast long enough to have missed a clear sunrise and Fred had to estimate according to a brightening sky - or worse, nothing more than DR, then Fred may never have had a reliable LOP / advance after all.  The effect might have been a delayed apparent sunrise - perhaps leading Fred to believe the flight had not progressed as far East as it really had - meaning the flight could have been furhter east by many minutes than what Fred believed.

What of latitude?  Fred needed the moon for that.  If 'on latitude' - one would hope they would break out anf overfly the island, happy day.  But if to north and moon shot delayed due to continuing oscurity, and already having misjudged Eastward progress, the flight might go wide and far - to NE.  One hopes if near right latitude and progressing too far East, Howland could be spotted or the plane seen or heard.  None of that happened.

So where did they come from and go to?  One looks again to the clouds to NW and North - if coming out of cloudy NW, and flight was unwittingly to north and still in oscured conditions in the north, it may have been a while before they broke out enough for Fred to get a moon shot.  If he was finally able to do that, then he may have reasonably pegged his latitude - but never realized how far East he had come.

We don't know, of course - and likely never will.  But pitiably, the flight may have been well to East of Howland, never realizing it - but on same latitude due to a later moon shot after breaking out.  Any smoke from Itasca would drift to West - away from the flight and leaving no sign underneath if to East of Howland.  Vis should have been better looking away from sun in that case, but perhaps there's a hint in there are really too far East to pick Howland out among the distant cloud shadows. 

This all suggests more clearly to me why Thompson saw things as he did on that morning - search to N / NE / NW.  One now wonders if Thompson's own error was in not realizing that maybe Noonan DID get a moonshot, and had his latitude reasonably pegged; that it may have been a tragic Easterly displacement that screwed things up. 

One now wonders if a two-step error went unrealized:
1. no clear sunrise, delay of apparent sunrise and therefore underestimating real ground speed / distance = flight further East than known. 
2. if to north - where clouds and known events suggested at time to Thompson, the moon shot may have been delayed, Fred may eventually have gotten the moon shot and got to the right latitude - where final 'on the line' call came: buzzing up and down the line 337-157, but tragical some miles to East...

Just thoughts.

- Jeff Neville

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Frederick Frick Young

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Re: What happened with the moon
« Reply #28 on: December 01, 2013, 11:11:25 AM »

Since this is my first post I'll say hello all a give a tidbit of my background!

I've been interested in AE's fate and reading this site for about 13 years.
I've also read Elgin Long's book, and am familiar with almost every site on the subject.

You may laugh, but I've been flying the FS Simulators since FS2000 version.
In the last couple of years several friends and myself have worked to develope a good model of Amelia's Lockheed L10E.
It is equipped with a sextant,driftmeter, E6B, and includes different gauge failures built to at random.
http://www.flightsim.com/vbfs/forumdisplay.php?10-MSFS-Multiplayer-Adventures

One of the persons who has developed this program has done extensive research on AE in several different locations including the Smithsonian and corresponded with Elgin Long, as well.

I'm also familiar with the Purdue University's Archives on Amelia Earhart the Putnam collection.   

I'm also a real world pilot and have been a Ham Radio Operator for years, so I know a bit about propagation, directional attennas, signal strengths, and mores code, which IMHO believe Amelia Earhart should have know as well.
All these things have led me to my own theories, but this post isn't about my opinion but is here for its factual value. 

I found researching this particular subject interesting and find it hard to believe anyone is inquiring as to whether or not FN used the MOON to navigate!

Of course he use the MOON as his primary LOP and this post will prove to you WHY he used it! 

Some sources, and I’m not pointing fingers, have suggested that FN was confused and was reading the wrong dated charts and instead of using Jul 3 data he may have been using Jul 2 data or vice versa. In fact one person goes into a very long dissertation, which is almost convincing, until you realize he fails to mention one very important detail, which would have been quite obvious with the use of the naked eye alone. (the MOON was available that night) The argument has also been supposedly confirmed by some navigator and that these chart errors could have put them 59.14 nm farther east or west of where they actually were.

I say nonsense! Here is a comparison of those two days of readings.
As example, if that were the case then the errors would have been as follows just before crossing the IDL (International Dateline)

For anyone who knows nothing or very little about celestial navigation here’s a crash course or refresher perhaps for navigators.

Fact: Fred N would have definitely taken three shots to acquire three LOP’s each time he was acquiring a fix at night. We know that from his Oakland to Hawaii records and that was protocol in those days.
You may ask why?

Take a piece of paper and draw a big X on it. Call where the lines intersect a two LOP fix. To confirm this fix the navigator takes another LOP and draws the third line on his graph. The third line should intersect exactly where the first two did. If not he knows exactly which one of the three LOPs is incorrect. And since the MOON would be the one so far off if he were reading the wrong day’s charts, he’d know it immediately. So he’d use at the next day’s chart, depending which side of the two star fix was, and recalculate.

Celestial Navigation Data for 1937 Jul 3 at 17:00:00 UT
Latitude S0* 06.1’ Longitude E 179* 56.1’
Object/GHA/Dec/Hc/ Zn
VENUS/ 122* 03.9'/ N16* 10.8'/ +30* 33.6'/ 71.1*
ACHERNAR 152* 27.1'/ S57* 32.9'/ +28* 29.2'/ 163.6*
MOON 139* 54.0'/ N17* 37.4'/ +46* 42.1'/ 63.7*

And readings from 1 day's charts at the some time and place.

Celestial Navigation Data for 1937 Jul 2 at 17:00:00 UT
Latitude S0* 06.1’ Longitude E 179* 56.1’
Object/ GHA/ Dec/ Hc/ Zn
VENUS/ 122* 04.8'/ N15* 56.4'/ +30* 37.0'/ 71.3*
ACHERNAR/ 151* 27.9'/ S57* 32.9'/ +28* 12.2'/ 163.1*
MOON 153* 09.0'/ N13* 34.9'/ +60* 02.1'/ 61.8*

The above star coordinates( VENUS and the MOON are the longitude (east and west) LOPs since their azimuths fall more vertically on the chart or, map if you’d rather think of it as such).
The difference in elevation of VENUS Hc is 3.4 minutes and Dec is 4.6 minutes.
The difference in elevation of ACHERNARs’ Hc is 17 minutes and Dec is 0 minutes (none).
(ACHERNAR is used to determine a latitude (north and south) LOP since its azimuth falls more horizontally on the chart or map).

Sometimes pictures help make things clearer
Draw a typical 30/60/90 degree (right triangle) and label it.
Label the 30 degree angle X to be the Hc (elevation angle) of the star, Side A is the side opposite of Angle A and represents the elevation of the star above the horizon, side B is the adjacent side (111nm) of angle A, and C is the hypotenuse. Use 28 degrees for Angle X.

In case you're wondering why 111nm, it is AE's average GS from the Lae Airstrip to when they reported being 200nm from Howland at 17:42 UT.

By using simple trigonometry (http://www.pagetutor.com/trigcalc/trig.html) as navigators do, for side B use 111, representing the distance traveled in an hour, and calculate. Increase or decrease angle X by 1 degree and leave side A's value and recalculate. Notice that only a difference of 5nm. Now divide 17 (minutes) by 60 (minutes) = .2833x5nm=1.4nm error.

Since each minute of latitude = 1nm and longitude (at or near the equator) is very close to 1nm, we can see that, if FN had used the wrong dated charts, the error differences in his star LOPs to acquire a fix, would only have been at most about a couple of miles. 

(The bubble sextant is only capable of reading within about 4-5nm while bouncing alone in an aircraft like the L10E). So you can see, the difference is quite negligible.

Which is the first point of this exercise of using the wrong day's data charts.

HOWEVER!! Since FN used the MOON as a 3rd LOP using the same method above notice a huge difference!

The MOON would surely be his primary celestial candidate, because of its brightness, accuracy of shooting a LOP with the sextant, and the simple fact that it’s changing its position faster than any another celestial bodies in the sky, including the Sun or planets.

Notice above, that by using the Moons’ LOP as a third source to acquire a fix, the difference in Hc’s are 14* 40’ and Dec’s 14* 14’ from one day to the next. Again, by using simple trigonometry, 111nm as Side B and an Hc of 46 for angle X and increase angle X by 14 degrees to 60. leave side A and recalculate and to see that side B decreases to a reading of 66nm, a difference of 45nm.   
Do the same and calculation and decrease the 46 by 14 = 32 and notice the error increases to 184 a difference of 73nm. 
Note: Since the Dec and Hc have both changed by  around 14 degrees, to be more accurate. you would merely use Pathagora’s Theorem a2 +b2 = c2. The difference in error between the two days would be a little more than 14 degrees. In this case I merely use 14 degrees which is close enough for illustration purposes.
 
Also note that the errors increase as take reading closer to the horizon which increases accuracy of readings of course.

So supposing FN was using the wrong chart and plotted two star LOPs to acquire a fix (where the two LOP lines intersect) and then acquired the MOON’s LOP. That line wouldn’t even come anywhere near to where the two star LOPs crossed to indicate a fix even if he was just one day off.

There's no doubt that FN would have used the MOON as a third shot since, as a trained navigator for many years, he knew this. If he was using the wrong day’s data he would have known immediately. Not after the crossing the date line and comparing two day's data. He would have known it by merely glancing at the charts and noticing the disparity. Anyone who has looked at the MOON on two different nights knows how much higher or lower it is from one day to the next.

We all know that AE and FN left Lae, NG for Howland island on the 3rd of July, local time.
However FS used July 2nd Charts to whole way since the charts based on GMT not locat time.
It made little difference to Fred when or where they crossed the ILD (International Date Line)
He only cared that he was changing from using a +179 degrees to a -179 degree for reference purposes.       

I hope this helps all to understand a little more about Celestial Navigation, the Sextant, and the myth about using incorrect charts.

Fred
« Last Edit: December 01, 2013, 12:22:46 PM by Frederick Frick Young »
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Bill de Creeft

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  • Posts: 63
Re: What happened with the moon
« Reply #29 on: December 01, 2013, 01:49:01 PM »

Thank you!
...and at this point I'd be interested in your 'theories'; you've got my attention at least.

I believe that it happened, basically, the way it's been laid out; it's hard, because of where it is, to prove it.
I believe that if we could see it all together, it would/will seem simple .

I just kind of think that they really did get there, and the explanation of that is interesting...but the proof is what's missing!

That has to wait...but explanations , and 'theories' are the essence of what makes waiting interesting, and practical experience results in simplicity...I think!
What do you think happened to get them where they ended up?
And do you think they ended up their days on Gardner Is. ?
I would be personally interested, given your background...
I think they did.
Bill
Bill de Creeft

Tighar Member #4131
 
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