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Author Topic: Working the Flight backwards  (Read 118351 times)

h.a.c. van asten

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Re: Working the Flight backwards
« Reply #90 on: September 08, 2011, 05:43:30 AM »

R.Conyers Nesbit found that wind from forecast 12 mph SE was actually 25 mph E @ medium altitudes (by which 45 min delay was incurred). [N.Met.Archive , Bracknell , Gr.Br.) . The mean equivalent headwind from 25 mph , 12 mph , 18 mph , 15 mph (last 3 from forecast) over 4 equal 639 mls tracks (to level transitional stages) was 16 mph , 26 kmh , 7 m/s , Bf. 4 .
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Ric Gillespie

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Re: Working the Flight backwards
« Reply #91 on: September 08, 2011, 08:11:09 AM »

Obviously they were satisfied with the accuracy of the navigation or they could have turned around and returned to Lae at the time of that first report and could have made it back to Rabaul up to the time of the second report as I showed with the point of no return calculation.

Supposition after supposition.  The fact that they didn't turn around tells us nothing other than that they didn't turn around. Earhart planned to find Howland by Radio Direction Finding. How much en route navigational accuracy did Earhart consider necessary for continuing the flight?  I don't know and you don't know. When did Earhart, on any of her long distance flights, ever turn around? On both the Oakland/Honolulu and Brazil/Senegal flights the aircraft was significantly off course for much of the flight.     

You have shown that there were airfields on Rabaul in 1937. Okay, good. Did Earhart know about them?  They don't appear on the strip maps that Clarence Williams prepared for her.  There's no reference to Rabaul in any of the pre-flight correspondence.  We don't know what charts Noonan used.

But putting those two reports behind us, there is no dispute about the logged  report of "partially cloudy" at 1623 Z, conditions that allowed Noonan to get a fix even if he had not been able to get one in the prior two hour period.

Supposition.  The log entry says only "HEARD EARHART (PART CLOUDY)."  The "(PART CLOUDY)" is typed over a dashed line and so was apparently added later. You interpret that entry to mean that Noonan could get a fix, but that is pure supposition.

Based on the normally accepted level of uncertainty for dead reckoning of 10% of the distance flown, from that point to 1912 Z it is very unlikely that their DR position would be more than 47 NM in error.

More supposition.

You wrote in an earlier post that Earhart could DR to Gardner with only a 7% uncertainty, which is better than the standard, so would improve the accuracy of the DR position.

I don't recall ever saying that.  I don't know what I would have based it on. 

These types of navigational errors have been extensively analyzed statistically.
So based on the science of navigation Noonan would never have gotten so far south of Howland so that it would have made any sense to abandon their efforts to find Howland and instead to fly off to far away Gardner.

Don't confuse statistics with science.  Science relies on evidence and the evidence says they reached Gardner.
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Gary LaPook

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Re: Working the Flight backwards
« Reply #92 on: September 08, 2011, 11:49:54 AM »

Obviously they were satisfied with the accuracy of the navigation or they could have turned around and returned to Lae at the time of that first report and could have made it back to Rabaul up to the time of the second report as I showed with the point of no return calculation.

Supposition after supposition.  The fact that they didn't turn around tells us nothing other than that they didn't turn around. Earhart planned to find Howland by Radio Direction Finding. How much en route navigational accuracy did Earhart consider necessary for continuing the flight?  I don't know and you don't know. When did Earhart, on any of her long distance flights, ever turn around? On both the Oakland/Honolulu and Brazil/Senegal flights the aircraft was significantly off course for much of the flight.     

You have shown that there were airfields on Rabaul in 1937. Okay, good. Did Earhart know about them?  They don't appear on the strip maps that Clarence Williams prepared for her.  There's no reference to Rabaul in any of the pre-flight correspondence.  We don't know what charts Noonan used.

But putting those two reports behind us, there is no dispute about the logged  report of "partially cloudy" at 1623 Z, conditions that allowed Noonan to get a fix even if he had not been able to get one in the prior two hour period.

Supposition.  The log entry says only "HEARD EARHART (PART CLOUDY)."  The "(PART CLOUDY)" is typed over a dashed line and so was apparently added later. You interpret that entry to mean that Noonan could get a fix, but that is pure supposition.

Based on the normally accepted level of uncertainty for dead reckoning of 10% of the distance flown, from that point to 1912 Z it is very unlikely that their DR position would be more than 47 NM in error.

More supposition.

You wrote in an earlier post that Earhart could DR to Gardner with only a 7% uncertainty, which is better than the standard, so would improve the accuracy of the DR position.

I don't recall ever saying that.  I don't know what I would have based it on. 

These types of navigational errors have been extensively analyzed statistically.
So based on the science of navigation Noonan would never have gotten so far south of Howland so that it would have made any sense to abandon their efforts to find Howland and instead to fly off to far away Gardner.

Don't confuse statistics with science.  Science relies on evidence and the evidence says they reached Gardner.
-----------------

Sure you did Ric. On August 31st your wrote:

"Amelia Earhart played the same game.  She was no Charles Lindbergh and she hit Ireland about 120 nautical miles off course. So, let's see .... if we use that as a measure of her ability to maintain a DR course (without any help from a navigator) it looks like she's about .07 nm off for every mile she flies by DR.  Worst case: If she DRed the entire distance between Howland and Gardner (about 350 nm) with no help from Noonan she should be off by roughly 24 miles.  That's hardly a scientific assessment but it's an interesting exercise."

".07 nm off for every mile she flies" is a 7% accuracy.

See:
https://tighar.org/smf/index.php/topic,447.0.html

gl
« Last Edit: September 08, 2011, 12:19:06 PM by Gary LaPook »
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Ric Gillespie

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Re: Working the Flight backwards
« Reply #93 on: September 08, 2011, 12:11:40 PM »

Sure you did Ric. On August 31st your wrote:

"Amelia Earhart played the same game.  She was no Charles Lindbergh and she hit Ireland about 120 nautical miles off course. So, let's see .... if we use that as a measure of her ability to maintain a DR course (without any help from a navigator) it looks like she's about .07 nm off for every mile she flies by DR.  Worst case: If she DRed the entire distance between Howland and Gardner (about 350 nm) with no help from Noonan she should be off by roughly 24 miles.  That's hardly a scientific assessment but it's an interesting exercise."

0.07 nm off for each mile she flies is a 7% uncertainty.

For crying out loud  ...  I said it was hardly a scientific assessment but it's an interesting exercise.  You're playing games.  I don't have time for games.
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h.a.c. van asten

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Re: Working the Flight backwards
« Reply #94 on: September 08, 2011, 01:16:28 PM »

Having not actually turned back , or communicating plans thereof says that the crew was convinced to have their train on the rails to destination .
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Harry Howe, Jr.

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Re: Working the Flight backwards
« Reply #95 on: September 08, 2011, 02:09:04 PM »


As Ric said "For crying out loud..."
I say... It's not Rocket or Nuclear Science.

They didn't fly  a direct route and arrive near Howland and not know which way to turn (N or S), or keep going East, or turn back West.  They flew an offset to the SSE, arrived at the LOP and knew exactly which way to turn  (NNW) and how far to fly (the length of the offset).  Arriving  at where they expected to see Howland but not spotting it, they continued NNW for some time miles, fuel, pick a number) then turned around ( radio message  "Circling...") and flew SSE,  again not spotting Howland, so they continued SSE in accordance with their Alternate Pplan B, i.e. fly to Gardner.
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
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Gary LaPook

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Re: Working the Flight backwards
« Reply #96 on: September 08, 2011, 02:18:11 PM »

Sure you did Ric. On August 31st your wrote:

"Amelia Earhart played the same game.  She was no Charles Lindbergh and she hit Ireland about 120 nautical miles off course. So, let's see .... if we use that as a measure of her ability to maintain a DR course (without any help from a navigator) it looks like she's about .07 nm off for every mile she flies by DR.  Worst case: If she DRed the entire distance between Howland and Gardner (about 350 nm) with no help from Noonan she should be off by roughly 24 miles.  That's hardly a scientific assessment but it's an interesting exercise."

0.07 nm off for each mile she flies is a 7% uncertainty.

For crying out loud  ...  I said it was hardly a scientific assessment but it's an interesting exercise.  You're playing games.  I don't have time for games.
--------------------------------------------------------

This is not a game, just normal navigational analysis. You show that she had been able to come within 7% of her destination on a much longer flight but now, on the much shorter leg from a 1627 Z fix, you claim that she can't DR within 50%, (a seven times larger error) which would have been the necessary error for them to end up closer to Gardner than to Howland. In prior discussions you used this 7% accuracy to claim that she could have easily DRed to Gardner but if she DRed as inaccurately as you are now saying that she did on this short leg then she would have missed Gardner by 175 NM.

If you don't like a 1627 Z fix then go all the way back to the takeoff at Lae. If Earhart and Noonan flew all the way from
Lae to Howland, 2222 NM, inside solid clouds without the opportunity to see any visual landmarks or to take any celestial sights, then it is highly unlikely that they were more than 222.2 NM away from Howland at 1912 Z. (Of course this is not a real scenario since Earhart wrote that "Noonan must have star sights" so they would have turned around if they could not see the stars.)

But wait, we know that they had a fix at 0718 Z near Nikumanu Island and it is only 1480 NM from there to Howland so the expected uncertainty would only be 148 NM if that was the last time they were able to get a fix. And then they saw the Ontario at 1030 Z which was only 1100 NM from Howland making the uncertainty at 1912 Z only 110 NM. Then they passed Nauru at about 1130 Z and it is only 990 NM from there to Howland, the uncertainty became 99 NM. Then they flew over Tabituea which is only 530 NM from Howland, further reducing the dead reckoning uncertainty to only 53 NM. And these numbers are based on using the standard 10% uncertainty, simply multiply these values by 0.7 to find the likely error using Earhart's 7% measurement. For example, using your 7% number for Earhart's DR acuracy they would have come within 155 NM of Howland even if they had to DR all the way from Lae.

So take your pick, normal DR should have brought them much closer to Holwand than to Gardner when they hit the sun line LOP. This is the same kind of analysis any flight navigator, including Noonan, makes and would have convinced Noonan that they were close to Howland so they would not have decided to give up searching for Howland and instead flown off to the far away Gardner.

gl

gl
« Last Edit: May 14, 2012, 04:50:56 PM by Gary LaPook »
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Gary LaPook

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Re: Working the Flight backwards
« Reply #97 on: September 08, 2011, 02:29:01 PM »


As Ric said "For crying out loud..."
I say... It's not Rocket or Nuclear Science.

They didn't fly  a direct route and arrive near Howland and not know which way to turn (N or S), or keep going East, or turn back West.  They flew an offset to the SSE, arrived at the LOP and knew exactly which way to turn  (NNW) and how far to fly (the length of the offset).  Arriving  at where they expected to see Howland but not spotting it, they continued NNW for some time miles, fuel, pick a number) then turned around ( radio message  "Circling...") and flew SSE,  again not spotting Howland, so they continued SSE in accordance with their Alternate Pplan B, i.e. fly to Gardner.
-------------------------
Because of the relationship of the approach course to Howland and the azimuth of the sun line LOP, it was a shorter diversion to intercept to the NNW than to the SSE so that is the way any flight navigator, including Noonan, would have flown the approach, from the NNW. In addition, due to the unique relationship of Baker to Howland, making the approach from the NNW provides additional safety since Baker would act as a backstop, in effect making the offset longer so less likely to be insufficient. Aiming to the SSE looses this advantage.

(Harry, if you don't want to actually draw the diagram then you can figure it out with trig using the law of cosines, but you knew that already.)


See flight navigational manuals here:
https://sites.google.com/site/fredienoonan/topics/landfall-procedure

and further discussion here:
https://sites.google.com/site/fredienoonan/discussions/navigation-to-howland-island

gl
« Last Edit: December 14, 2011, 03:10:36 AM by Gary LaPook »
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Harry Howe, Jr.

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Re: Working the Flight backwards
« Reply #98 on: September 08, 2011, 02:59:45 PM »


The difference in dstance flown, for the  same length offset, with a SSE offset is slightly shorter than with a NNW offset, but not significantly so. The main advantage of the SSE to NNW approach is that the bright rising sun is at your back not in your face (eyes) when flying the LOP and  when trying to spot that little sliver of land called Howland..  Arriving from the SSE (a SSE offset) Baker would be encountered  some time ( a known time, about 20 minutes or so) before Howland, however it is even smaller than Howland and presumably harder to spot.
No Worries Mates
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Harry Howe, Jr.

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Re: Working the Flight backwards
« Reply #99 on: September 08, 2011, 03:45:57 PM »



Gary
Baker as a backstop?  Backstop to what?  It's smaller than Howland,  merely a dimple on the surface of the ocean, and certainly no place to land a plane.  However, if one were to  be rquired to "ditch" the aircraft at sea it would make sense to get as close as possible  to the nearest point of land and hope that the plane's momentum could get its nose against that land.
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Gary LaPook

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Re: Working the Flight backwards
« Reply #100 on: September 08, 2011, 03:47:05 PM »


The difference in dstance flown, for the  same length offset, with a SSE offset is slightly shorter than with a NNW offset, but not significantly so. The main advantage of the SSE to NNW approach is that the bright rising sun is at your back not in your face (eyes) when flying the LOP and  when trying to spot that little sliver of land called Howland..  Arriving from the SSE (a SSE offset) Baker would be encountered  some time ( a known time, about 20 minutes or so) before Howland, however it is even smaller than Howland and presumably harder to spot.

--------------------------------

I'm sorry Harry, but you just don't seem to get how the offset (landfall) approach is done. As to the first part of your statement is is LONGER if intercepting to the SSE than to the NNW. Perhaps you should get out a piece of paper and  your plotter and draw it out. Make a dot in the center of your paper that represents Howland. Draw a line from that dot at 258° which is the approach course from Lae. Next draw a line extending 157-337° through the Howland dot and extending the same length in both directions.  Now pick any arbitrary point on the 258° approach course and measure the distance from that chosen spot to both ends of the 157-337° LOP line and you will see that it is further to the SSE end than it is to the NNW end.

As to the second part of your statement, approaching the LOP the sun will be almost directly in front of you depending on the offset you have chosen. After you intercept the LOP and turn to follow it, the sun will be on your wingtip since the azimuth to the sun is at right angles to the LOP that you are following. If you intercept to the SSE then the sun will be on the right wingtip. If you intercept to the NNW then the sun will be on the left wing tip. The sun will not be behind you if following the LOP from the SSE.

In addition to the two previous reasons I listed that favored the NNW intercept there are two more. A special, optically flat, window had only been installed on the left side of the aircraft for taking celestial observations so as to minimize any error caused by refraction. Using the normal landfall procedure that Noonan would have been using, you continue to take additional observations of the sun after the interception to ensure accurately tracking the LOP. Putting the sun out on the left wingtip, so that the better celestial viewing window was available, would maximize the accuracy of those critical observations.

The second additional reason to intercept to the NNW is that as the day goes on the azimuth of the sun rotates counter-clockwise which moves the LOP closer to one performing a NNW intercept and further away from one if attempting an intercept to the SSE. So if running late, and low on fuel, the NNW intercept will allow a shorter flight and more of a fuel reserve. You can draw this out on your diagram. If they were running even later, say starting the approach two hours later at 2112 Z, at that time the azimuth of the sun had changed to 058° true making the resulting LOP run 148-328°. Draw in this new LOP and make the same measurements and you will see that is is now a much shorter run into Howland from the NNW than from the SSE.

See:

https://sites.google.com/site/fredienoonan/resources/weems/weems-394-395.JPG?attredirects=0

https://sites.google.com/site/fredienoonan/resources/weems/weems-396-397.JPG?attredirects=0

https://sites.google.com/site/fredienoonan/topics/landfall-procedure

https://sites.google.com/site/fredienoonan/discussions/navigation-to-howland-island

gl
« Last Edit: September 09, 2011, 12:25:46 AM by Gary LaPook »
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Gary LaPook

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The broken page
« Reply #101 on: September 08, 2011, 04:02:48 PM »



Gary
Baker as a backstop? Backstop to what?  It's smaller than Howland,  merely a dimple on the surface of the ocean, and certainly no place to land a plane.  However, if one were to  be rquired to "ditch" the aircraft at sea it would make sense to get as close as possible  to the nearest point of land and hope that the plane's momentum could get its nose against that land.
-----------------------------


Let's say, for example, that Noonan had figured that his maximum error in his DR, since the last fix, was 60 NM and so then he had aimed 60 NM north- northwest of Howland, Baker then provided an even larger safety margin, they would have to have been more than 98 NM off course to the south at the point of intercepting the LOP to actually pass south of Baker and so turn the wrong way, away from Howland because Baker is 38 NM SSE of Howland. In fact, with 20 NM visibility, they would have had to pass 20 NM south of Baker to miss seeing it, making the safety margin even greater since they would have had to have been more than 118 NM, (almost double Noonan's estimate of maximum DR error in this example) off course to miss seeing Baker. Once you see Baker it is trivial to DR 38 NM to Howland.

gl
« Last Edit: September 09, 2011, 12:25:01 AM by Gary LaPook »
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Irvine John Donald

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Re: The broken page
« Reply #102 on: September 08, 2011, 05:15:04 PM »

Gentlemen...

In tne absence of any information from AE and FN on the events of that trip all we actually know, right now, is that they did not make it to Howland. Period. Full stop.  The Niku theory says they perished on Gardner after landing there and transmitting for a few nights. TIGHAR has spent many years and many dollars trying to prove this theory. Others have spent many years and many dollars to prove their theory and discredit TIGHAR.
We can only "theorize" as to the events of that night. There are so many variables to consider that we sometimes blur the difference between hard evidence and other people's theories.

Ric and others (Marty gets a lot of credit here) really spend a great deal of time trying to keep fact from fiction. This must be a difficult task.  For example... This thread. People keep insisting that the duo coulda, woulda, shoulda DR'd right to Gardner after missing Howland. Some threads even suggest the DR'ing (?) was done from Howland.  How is it possible to suggest this as fact?  If they missed Howland then where were they? How can they DR from a position that must be suspect by FN?  No where does it say they planned to travel to Gardner as plan b. We don't even know if there was a plan b. 

The purpose behind this thread was to suggest an alternate methodology to the standard approach in thinking about what "might" have transpired after takeoff from Lae.  And to work backwards from the TIGHAR Niku theory that they ended their journey on Gardner in the hope we might learn something new or stimulate some more thought.

I think we have so much evidence pointing to the Niku theory as being right that we have forgotten the basic fact that they left Lau never to be seen again. 
Respectfully Submitted;

Irv
 
« Last Edit: September 08, 2011, 05:25:03 PM by Irvine John Donald »
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Irvine John Donald

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Re: The broken page
« Reply #103 on: September 08, 2011, 10:40:57 PM »

I do have one question I would like to ask Mr. LaPook.  In reading your website it is clear that you disagree with the TIGHAR theory. My question is simple.  What do you believe happened to AE and FN?  I couldn't find that info on your website.
Respectfully Submitted;

Irv
 
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Gary LaPook

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Re: The broken page
« Reply #104 on: September 09, 2011, 12:47:58 AM »

Obviously they were satisfied with the accuracy of the navigation or they could have turned around and returned to Lae at the time of that first report and could have made it back to Rabaul up to the time of the second report as I showed with the point of no return calculation.

Supposition after supposition.  The fact that they didn't turn around tells us nothing other than that they didn't turn around. Earhart planned to find Howland by Radio Direction Finding. How much en route navigational accuracy did Earhart consider necessary for continuing the flight?  I don't know and you don't know. When did Earhart, on any of her long distance flights, ever turn around? On both the Oakland/Honolulu and Brazil/Senegal flights the aircraft was significantly off course for much of the flight.     

You have shown that there were airfields on Rabaul in 1937. Okay, good. Did Earhart know about them?  They don't appear on the strip maps that Clarence Williams prepared for her.  There's no reference to Rabaul in any of the pre-flight correspondence.  We don't know what charts Noonan used.

But putting those two reports behind us, there is no dispute about the logged  report of "partially cloudy" at 1623 Z, conditions that allowed Noonan to get a fix even if he had not been able to get one in the prior two hour period.

Supposition.  The log entry says only "HEARD EARHART (PART CLOUDY)."  The "(PART CLOUDY)" is typed over a dashed line and so was apparently added later. You interpret that entry to mean that Noonan could get a fix, but that is pure supposition.

Based on the normally accepted level of uncertainty for dead reckoning of 10% of the distance flown, from that point to 1912 Z it is very unlikely that their DR position would be more than 47 NM in error.

More supposition.

You wrote in an earlier post that Earhart could DR to Gardner with only a 7% uncertainty, which is better than the standard, so would improve the accuracy of the DR position.

I don't recall ever saying that.  I don't know what I would have based it on. 

These types of navigational errors have been extensively analyzed statistically.
So based on the science of navigation Noonan would never have gotten so far south of Howland so that it would have made any sense to abandon their efforts to find Howland and instead to fly off to far away Gardner.

Don't confuse statistics with science.  Science relies on evidence and the evidence says they reached Gardner.
-----------------------------------------------

So it appears that your position regarding the Rabaul airport is that, if it is not depicted on the Williams chart, then neither Earhart nor Noonan whould know of its existence.

O.K. I'll buy that position.

So I take it now, that to be consistent, that you are now also taking the position that neither Earhart nor Noonan knew of the existence of the Phoenix Islands since they are not depicted on the Williams chart either. So we can now agree that they could not have flown down the LOP to those islands since they did not know of their existence.

Agreed!

gl
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