TIGHAR

Amelia Earhart Search Forum => Celestial choir => Topic started by: pilotart on October 27, 2009, 11:31:42 PM

Title: Why 10AM from Lae?
Post by: pilotart on October 27, 2009, 11:31:42 PM
Public Television just ran an encore of The Final Hours: Amelia Earhart's Last Flight and USMC Major Bowen Weisheit (ret.) made a point of how Fred planned that exact 10 AM take-off time from Lae in order to cross the Equator at the 180° Meridian at exactly local sunrise.

 ??? He said this would give Fred the best sunrise shot to extend his LOP through Howland, still over 200NM @ 076° or 077° TC or about two hours at 'light weight' max range cruise speed with a little headwind.  (He also mentioned that Fred would have off-set a little South from that point to aim between Howland and Baker.)

I am asking on Celestial Choir because I thought all you needed for that Sunrise LOP would be an accurate chronometer and an estimated Latitude and elevation.

Was there ever a thought or recommendation for an earlier take-off time?

I know that I would want All Possible NavAids available for spotting that tiny island and an 8AM Departure would have allowed triangulation (or quadrangulation?) before daylight obscured Star Shots and allowed more precise Latitude as well as Ground Speed estimates further into the flight.

More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

Major Weisheit also wrote a book:   http://search.barnesandnoble.com/Last-Flight-of-Frederick-J-Noonan-and-Amelia-Earhart/Bowen-P-Weisheit/e/9780965856003# (http://search.barnesandnoble.com/Last-Flight-of-Frederick-J-Noonan-and-Amelia-Earhart/Bowen-P-Weisheit/e/9780965856003#) in 1996 and he made a point (in the TV Show) of how Amelia had over-ridden Fred’s instruction to turn South for Dakar at the coast, causing that loss of positional awareness.

He seemed to think that the greatest error came from Amelia discounting Fred's Nav Advice and ‘circling’ something like 15NM before Howland.  (He was from the 'splashed-down' crowd,  :-\ but that was before TIGHAR had found all that evidence.)  :)

'LTM'

Art

ps: Link to IMDb page for the TV show:  http://www.imdb.com/title/tt0835032/ (http://www.imdb.com/title/tt0835032/)





Title: Re: Why 10AM from Lae?
Post by: Martin X. Moleski, SJ on October 28, 2009, 07:24:58 AM
Public Television just ran an encore of The Final Hours: Amelia Earhart's Last Flight and USMC Major Bowen Weisheit (ret.) made a point of how Fred planned that exact 10 AM take-off time from Lae in order to cross the Equator at the 180° Meridian at exactly local sunrise.

He said this would give Fred the best sunrise shot to extend his LOP through Howland, still over 200NM @ 076° or 077° TC or about two hours at 'light weight' max range cruise speed with a little headwind.  (He also mentioned that Fred would have off-set a little South from that point to aim between Howland and Baker.)

How good are Weisheit's sources?  Does he have letters from Fred?  How much is his argument based on the conviction that "this is what Fred could or would or should  have done"?

Playing "coulda woulda shoulda" is fun, but it should be identified as a game and not as reliable evidence.   (Ooops!  I just noticed that I'm playing the game.  You have been notified!   ;D

The best documentation we have about the day itself is the Chater Report. (http://www.tighar.org/Projects/Earhart/Documents/Chater_Report.html)  It suggests to me that 10:00 AM was the earliest they could get away after the final time check that morning.

Quote
I am asking on Celestial Choir because I thought all you needed for that Sunrise LOP would be an accurate chronometer and an estimated Latitude and elevation.

I'm not part of the choir, but I think you're right.   ;)

Quote
Major Weisheit also wrote a book:   http://search.barnesandnoble.com/Last-Flight-of-Frederick-J-Noonan-and-Amelia-Earhart/Bowen-P-Weisheit/e/9780965856003# (http://search.barnesandnoble.com/Last-Flight-of-Frederick-J-Noonan-and-Amelia-Earhart/Bowen-P-Weisheit/e/9780965856003#) in 1996 and he made a point (in the TV Show) of how Amelia had over-ridden Fred’s instruction to turn South for Dakar at the coast, causing that loss of positional awareness.

Here is a review from the old Forum by Jerry Hamilton:
Quote
Date:         Tue, 21 Mar 2000 14:07:52 EST
From:         Jerry Hamilton
Subject:      AE TV Special

Just saw the new public TV special about AE. It was produced by South Carolina E-TV (related to a university?). The best thing about it was the video. Lots of motion shots of AE, Fred, and the Lockheed. Also some nice in-flight shots of Lynch's Lockheed. The story narration mostly uses AE's own reports from the world flight, which I thought was effective. However, beyond the pretty pictures, it's difficult to understand why this special was produced. It offers no new information, theories, perspectives, or explanations.

Fred's "problem" is raised midway through, but disappears and is not mentioned again. They rely totally on Bowen Weisheit's theory of what went wrong, with a few additional comments by the National Air & Space Museum folks, and he gets lots of TV face time. He was a navigation instructor in the military, flew in the Pacific during WWII, and received training at the Weems school. Because of his background, he believes he knows how Fred would have planned and executed the Howland flight. Unfortunately, most of his theory is based on what he thinks AE did, not what Fred did. He believes that at 200 miles out Fred wanted to turn slightly to the south of the direct route to Howland to bisect both it and Baker (better odds of finding one or both). He says AE refused this direction and continued straight in. He further says she turned north on the 157/337 LOP instead of south as Noonan directed. In short, Bowen thinks AE totally ignored her navigator at the end of the flight and they splashed into the sea. No mention of other alternative flight endings, researchers, or even Elgin Long.

Watch it for the pretty pictures. Blue skies, -jerry

                               Marty
Title: Re: Why 10AM from Lae?
Post by: Mark Petersen on January 23, 2011, 10:53:12 PM
More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

I was thinking about exactly this the other day.  The problem is that if they started the flight later in the day and missed seeing the searchlights they would have to continue on their path and wait for dawn (which would be about another hour or so away).  Once a dawn line is established, they would have their current LOP, and then they would have to backtrack to the advanced LOP (which would be about another hour back) and only then would they be in a position to spot Howland during the daylight.  All of this would increase their flight time, increase navigation error (longer flight means more dead reckoning errors) and burn their fuel reserves, so it would probably look like an all or nothing gambit to FN.  

I would think that FN would want to avoid overshooting Howland as a high priority and would therefore want to get a dawn line before hitting the LOP, and of course he was of the assumption that AE would be able to do the rest with her RDF skills (or lack thereof).  

LTM,
Mark
Title: Re: Why 10AM from Lae?
Post by: Martin X. Moleski, SJ on January 24, 2011, 04:45:49 AM
More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

I was thinking about exactly this the other day.  The problem is that if they started the flight later in the day and missed seeing the searchlights they would have to continue on their path and wait for dawn (which would be about another hour or so away). ...

So far as I know, TIGHAR has not found a document from 1937 explaining the actual rationale for the 0000 GMZ takeoff from Lae (10:00 AM local time). 

What we do have evidence of is the expected time of arrival calculated before the takeoff:

"Finally, just before 8:00 PM aboard Itasca, official notification of Earhart’s departure arrived from Lae, via Samoa: 'Urgent, Black, Itasca . . . Amelia Earhart left Lae at 10 AM local time July 2nd. Due Howland Island 18 hours time.' This information presented a new picture. The plane had left Lae two hours earlier than previously reported, and the eighteen-hour time-en-route estimate indicated that Earhart anticipated lighter headwinds than predicted in the most recent forecast. Itasca should now expect the plane to arrive at around 6:30 AM" (Finding Amelia, p. 85).
Title: Re: Why 10AM from Lae?
Post by: Mark Petersen on January 24, 2011, 05:22:12 PM
More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

I was thinking about exactly this the other day.  The problem is that if they started the flight later in the day and missed seeing the searchlights they would have to continue on their path and wait for dawn (which would be about another hour or so away). ...

So far as I know, TIGHAR has not found a document from 1937 explaining the actual rationale for the 0000 GMZ takeoff from Lae (10:00 AM local time). 

What we do have evidence of is the expected time of arrival calculated before the takeoff:

"Finally, just before 8:00 PM aboard Itasca, official notification of Earhart’s departure arrived from Lae, via Samoa: 'Urgent, Black, Itasca . . . Amelia Earhart left Lae at 10 AM local time July 2nd. Due Howland Island 18 hours time.' This information presented a new picture. The plane had left Lae two hours earlier than previously reported, and the eighteen-hour time-en-route estimate indicated that Earhart anticipated lighter headwinds than predicted in the most recent forecast. Itasca should now expect the plane to arrive at around 6:30 AM" (Finding Amelia, p. 85).

Thanks for the info Marty.  I'm not a navigator, but given a long flight, it seems like common sense to measure the dawn line before reaching a destination (and not too long before reaching it).  I'm sure other factors might intervene in the decision making process, but from a navigational standpoint it seems like common sense.  Your info seems to support this logic. 
Title: Re: Why 10AM from Lae?
Post by: Martin X. Moleski, SJ on January 24, 2011, 05:46:54 PM
... I'm not a navigator, but given a long flight, it seems like common sense to measure the dawn line before reaching a destination (and not too long before reaching it).  I'm sure other factors might intervene in the decision making process, but from a navigational standpoint it seems like common sense.  Your info seems to support this logic. 

Sun lines are no more and no less helpful than any other celestial sighting.

Any observation gives you a LOP that you may cross with another LOP (or two) to give you a fix.

All we can say for sure is that AE and FN's original flight plan and ETA would have put them at Howland about a half-hour past dawn, which does mean that it would have allowed for a sun line to be derived from the dawn sighting.  But the plan including using Radio Direction Finding (RDF) to get the last bearings they needed to reach Howland; it's hard to guess how much weight Fred would have put on getting sun sightings while doing the flight-planning, given a pretty positive experience in the past with RDF.
Title: Re: Why 10AM from Lae?
Post by: Mark Petersen on January 24, 2011, 06:48:47 PM
Sun lines are no more and no less helpful than any other celestial sighting.

Not more or less helpful, but I would think that sun lines are much easier to sight than other celestial sightings.  Trying to spot a rising star through a cloud at the horizon would probably be very difficult, but next to impossible to miss with the sun.  So I'm guessing (again not a Navigator) that sighting a dawn line not long before reaching a destination would be deemed by a navigator as the lowest risk option.  (Where is Bob Brandenburg when we need him?  :)  )

Quote
All we can say for sure is that AE and FN's original flight plan and ETA would have put them at Howland about a half-hour past dawn, which does mean that it would have allowed for a sun line to be derived from the dawn sighting.  But the plan including using Radio Direction Finding (RDF) to get the last bearings they needed to reach Howland; it's hard to guess how much weight Fred would have put on getting sun sightings while doing the flight-planning, given a pretty positive experience in the past with RDF.

Given the well known risks of such a long, over-water journey to such a small island in the middle of nowhere, I'm guessing (and again just a guess) that FN wanted to leave as little as possible to chance, even knowing that they had an RDF.  I'll bet that he applied his navigational bag of tricks to the best of his ability.  If anything, he did this just to give them a little extra fuel reserves to work the RDF if needed.  Just a guess though (sorry, but I can't help but conjecture and think aloud with these "what-if" discussions   :D). 

Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on January 25, 2011, 07:29:07 AM
The 10:00 a.m. local / 0000 Greenwich thing was apparently just a coincidence - a handy one to be sure - but not an essential part of the plan. The previous day Earhart had planned to depart at 09:30 local but Fred couldn't get an accurate time hack for his chronometer.

There is also the question of exactly what time the plane left the ground. Was 10:00 the time they started engines?  The time they taxied out?  The time they began the takeoff run?  We just don't know, but neither is it terribly important that we know.  We have so little real information about what happened once the plane left Lae that it's folly to think that it's possible calculate subsequent events with minute-to-minute precision. 
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on April 24, 2011, 02:31:49 PM
Moleski . Bowen Weisheit , with his Earhart-Noonan disapproval theory is good in romanticism and less in Wisdom.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on April 24, 2011, 02:57:13 PM
R.G. By exact recomputation of the 0720 GMT radioed fix to 071545 GAT , 021930 GMT sunset , 67 percent of the journey´s half receives reasonable ETA - position groups : Gagan 043953 GAT , Fix 071545 GAT , Nukumanu 072633 GAT , Nauru In.Pt. 102945 ("lights in sight ahead" , radio , at 123 mi off Nauru´s industrial illuminations ; vis.range frm 8,000 ft 107 mls , frm 12,000 ft 132 mi to horizon). Earhart transmission heard at Nauru , reported "aircraft did not come nearer". From In.Pt. to Nikunau 766 mls , arrival 153611 GAT , 1540 GMT , to Howland distance 498 loxo.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on April 25, 2011, 12:24:48 AM
"Lights" , or , "Ship" in sight ahead , 1030 GMT. Purdue file VIII , I.6. : Cable Rabaul Isl. to Earhart (no date) : "New nauru fixed light latitude 0.32 S / longitude 166.56 E five thousand candlepower 560 ft above sea level visible from shios to naked eye at 34 miles (stat. vs naut. no indication , Ast) Also there will be bright lighting all night on island from phosphate workings" . We do not know if or not Noonan himself asked for a report on Nauru lights w.r.t. his flight plan. The "Lights in sight ahead" report is from a letter by T.H.Cude , 1937 Nauru director of police , to F.X.Holbrook claiming that the word "Lights" not "ship" have been heard in the Earhart transmission on 3105 kcs.
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on April 25, 2011, 09:04:33 AM
There is no indication that Noonan requested any information about Nauru. The cable mentioning the new light appears to have been simply a courtesy appended to a weather report.

The "Lights in sight ahead" report is from a letter by T.H.Cude , 1937 Nauru director of police , to F.X.Holbrook claiming that the word "Lights" not "ship" have been heard in the Earhart transmission on 3105 kcs.

The original source is a State Department telegram from Sydney, Australia dated July 3m 1937, which reads: “Amalgamated Wireless state information received that report from ‘Nauru’ was sent to Bolinas Radio ‘at 6.31, 6.43 and 6.54 PM Sydney time today on 48.31 meters (6210 kHz), fairly strong signals, speech not intelligible, no hum of plane in background but voice similar that emitted from plane in flight last night between 4.30 and 9.30 P.M.’ Message from plane when at least 60 miles south of Nauru received 8.30 P.M. Sydney time, July 2 saying ‘A ship in sight ahead.’ Since identified as steamer Myrtle Bank sic which arrived Nauru daybreak today."

Unless Mr. Cude  produced the actual radio log for that night, the contemporary written record (the State Dept. telegram) trumps his 20+ year-old recollection.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on April 27, 2011, 01:35:49 AM
More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

I was thinking about exactly this the other day.  The problem is that if they started the flight later in the day and missed seeing the searchlights they would have to continue on their path and wait for dawn (which would be about another hour or so away). ...

So far as I know, TIGHAR has not found a document from 1937 explaining the actual rationale for the 0000 GMZ takeoff from Lae (10:00 AM local time). 

What we do have evidence of is the expected time of arrival calculated before the takeoff:

"Finally, just before 8:00 PM aboard Itasca, official notification of Earhart’s departure arrived from Lae, via Samoa: 'Urgent, Black, Itasca . . . Amelia Earhart left Lae at 10 AM local time July 2nd. Due Howland Island 18 hours time.' This information presented a new picture. The plane had left Lae two hours earlier than previously reported, and the eighteen-hour time-en-route estimate indicated that Earhart anticipated lighter headwinds than predicted in the most recent forecast. Itasca should now expect the plane to arrive at around 6:30 AM" (Finding Amelia, p. 85).

From telegrams it is known that several takeoff times have passed in review. Leaving the runway at your standard time zero hours is of practical importance for DR since it averts continuously reckoning backwards to non-zero time points. To reach the Greenwich anti meridian at exact sunrise is imho no option , since sunrise o/b of an aircraft is extremly dependent of the groundspeed which is for long range flights impossibly predictable in anticipation (Nukumanu , e.g. was reached with 44 minutes delay due headwinds stronger than from forecast).
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on May 23, 2011, 01:01:35 PM
More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

I was thinking about exactly this the other day.  The problem is that if they started the flight later in the day and missed seeing the searchlights they would have to continue on their path and wait for dawn (which would be about another hour or so away). ...

So far as I know, TIGHAR has not found a document from 1937 explaining the actual rationale for the 0000 GMZ takeoff from Lae (10:00 AM local time). 

What we do have evidence of is the expected time of arrival calculated before the takeoff:

"Finally, just before 8:00 PM aboard Itasca, official notification of Earhart’s departure arrived from Lae, via Samoa: 'Urgent, Black, Itasca . . . Amelia Earhart left Lae at 10 AM local time July 2nd. Due Howland Island 18 hours time.' This information presented a new picture. The plane had left Lae two hours earlier than previously reported, and the eighteen-hour time-en-route estimate indicated that Earhart anticipated lighter headwinds than predicted in the most recent forecast. Itasca should now expect the plane to arrive at around 6:30 AM" (Finding Amelia, p. 85).

From telegrams it is known that several takeoff times have passed in review. Leaving the runway at your standard time zero hours is of practical importance for DR since it averts continuously reckoning backwards to non-zero time points. To reach the Greenwich anti meridian at exact sunrise is imho no option , since sunrise o/b of an aircraft is extremly dependent of the groundspeed which is for long range flights impossibly predictable in anticipation (Nukumanu , e.g. was reached with 44 minutes delay due headwinds stronger than from forecast).


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

It appears that the 10 am takeoff was pretty random and not linked to navigational considerations. Although this time provided a convenient time to be approaching Howland, just shortly after being able to obtain a star fix and with the sun available for final approach (at least as a backup) , prior radiograms from Earhart had announced other, different, departure times. As further proof that having a recent star fix was not a consideration,  we only have to look at the planned Hawaii to Howland flight. They had planned to depart at 11pm Hawaii time (0930 Z) which would have put them at Howland at about 2100 Z, 9:30 am Itasca time. They actually attempted the takeoff at 5:40 am Hawaii time ( 1610 Z) so would have arrived at Howland at about 0340 Z, 4:10 pm Itasca time with no opportunity for star or moon fixes.

Gary LaPook
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on May 23, 2011, 01:57:53 PM
Public Television just ran an encore of The Final Hours: Amelia Earhart's Last Flight and USMC Major Bowen Weisheit (ret.) made a point of how Fred planned that exact 10 AM take-off time from Lae in order to cross the Equator at the 180° Meridian at exactly local sunrise.

 ??? He said this would give Fred the best sunrise shot to extend his LOP through Howland, still over 200NM @ 076° or 077° TC or about two hours at 'light weight' max range cruise speed with a little headwind.  (He also mentioned that Fred would have off-set a little South from that point to aim between Howland and Baker.)

I am asking on Celestial Choir because I thought all you needed for that Sunrise LOP would be an accurate chronometer and an estimated Latitude and elevation.

Was there ever a thought or recommendation for an earlier take-off time?

I know that I would want All Possible NavAids available for spotting that tiny island and an 8AM Departure would have allowed triangulation (or quadrangulation?) before daylight obscured Star Shots and allowed more precise Latitude as well as Ground Speed estimates further into the flight.

More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

Major Weisheit also wrote a book:   http://search.barnesandnoble.com/Last-Flight-of-Frederick-J-Noonan-and-Amelia-Earhart/Bowen-P-Weisheit/e/9780965856003# (http://search.barnesandnoble.com/Last-Flight-of-Frederick-J-Noonan-and-Amelia-Earhart/Bowen-P-Weisheit/e/9780965856003#) in 1996 and he made a point (in the TV Show) of how Amelia had over-ridden Fred’s instruction to turn South for Dakar at the coast, causing that loss of positional awareness.

He seemed to think that the greatest error came from Amelia discounting Fred's Nav Advice and ‘circling’ something like 15NM before Howland.  (He was from the 'splashed-down' crowd,  :-\ but that was before TIGHAR had found all that evidence.)  :)

'LTM'

Art

ps: Link to IMDb page for the TV show:  http://www.imdb.com/title/tt0835032/ (http://www.imdb.com/title/tt0835032/)







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

Weisheit's theory never made any sense since there is nothing magical or of any particular navigational significance of the intersection of the equator and the 180th meridian, his "Point X." Since these are imaginary lines they are very difficult to see from an airplane especially from 10,000 feet. (Maybe they can be seen from the level of a ship's bridge.)

The  sunrise table in the almanac states that the sunrise would occur at the equator at 6:00 am local mean time (LMT) on July 2nd but is only correct at the Greenwich meridian, not exactly half way around the world. And this table only states the time of sunrise to the nearest whole minute so the actual time of sunrise could be plus or minus 30 seconds making an uncertainty in the longitude of at least 15 or 15 NM. (This plus and minus 30 seconds is not a random type of error so there is no reason to believe that it would tend to be nearer to the center of the band of uncertainty, every time within the band is equally probable.) I say "at least" because there are other sources of uncertainty for such an observation. The time is stated for an observer at sea level and the sunrise is observed earlier at altitude. Weisheit  acknowledges this error by stating in his book that it would be 36' (36 NM) if flying at 1000 feet but it would be 147 NM if flying at 10,000 feet and the information to even compute this error was not available until 1951. Add to this additional uncertainty in the refraction of such low altitude sights and the uncertainty in the altitude of the plane after flying 2,000 nm without an updated altimeter setting, which would have affected the computation if it could have even been attempted by Noonan.

Gary LaPook

Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on May 25, 2011, 10:25:11 AM
G.Lapk. Sine the Almanac sunrise time is in L.Mean.T. , the correct U.L. sunrise time at any meridian around the world can be found by applying the latitude in time units to the Almanac (interpolated) figures. The reason is that Mean Time is registered by an artifical sun , orbiting the celestial horizon with unifform acceleration at exactly 15 deg / hr. If checked by the spherics formula for sunrise U.L. at any meridian , a same sunrise time like by the Almanac listing is consistently found in hours, minutes and seconds. Seconds digits are not listed in the Almanac , outcomes are finished to minutes.
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on May 26, 2011, 09:44:17 PM
G.Lapk. Sine the Almanac sunrise time is in L.Mean.T. , the correct U.L. sunrise time at any meridian around the world can be found by applying the latitude in time units to the Almanac (interpolated) figures. The reason is that Mean Time is registered by an artifical sun , orbiting the celestial horizon with unifform acceleration at exactly 15 deg / hr. If checked by the spherics formula for sunrise U.L. at any meridian , a same sunrise time like by the Almanac listing is consistently found in hours, minutes and seconds. Seconds digits are not listed in the Almanac , outcomes are finished to minutes.

--------------------------------------------------------------------------------
You are attempting to use the sunrise table for a purpose it was not designed for.
You must know the general rule that you can not go beyond the precision of your data but you
somehow attempt to massage the data in the sunrise table to get a greater level of precision than
the level of precision existing
in the original data. The sunrise table in the Nautical Almanac is only approximate and is only to
a precision of plus and minus 30 seconds (only to the nearest whole minute (and only at the
Greenwich meridian) and then for a three day period) and  is used for planning purposes only and
not for actual celestial navigation calculations. It is the main data tabulated in the almanac for
declination and Greenwich Hour Angle  that are actually used for celestial navigation
computations. The most important use of the sunrise  table is so the marine navigator can
set his alarm clock so that he gets out of bed early enough to take a morning round or stars on
ship board during the short twilight period when the stars are still visible and the horizon has also
become visible. It has no such importance for a flight navigator since he can take star sights all
night
long with his bubble sextant so the twilight period is not important to him. Another use of it for a
marine navigator is by looking at the sunrise or sunset table (and the twilight tables) and then at
the derived time entry for Aries he knows the approximate LHA Aries at twilight so can easily
use H.O. 249 volume 1 for selected stars to preplan his shooting schedule.

 A really simple way to show that the sunrise table can’t be used in the manner that you attempt
to use it is to look at the subsequent three day period starting, with July 5th, where it gives the
time of sunrise as 0601, exactly one minute later than the 0600 time given for the period of July 1
though 4 that you used. Ask yourself this question, how did the time of sunrise change by exactly
one whole minute between July 4th and 5th? Did the earth stop rotating for exactly one minute and
then start rotating again?

Basic to your premise is your computation of the time of sunrise at the location that you think the
plane was, at the time of sunrise.  You step  through this computation like this on page 28 of the
2008 article:


“Offset Fix had to be established. In
Noonan's case with the aireraft's 150 mph cruise
speed, this Fix had to be precomputed forthe coordinates
pair (178?47'-W;OOOO9'-N) at 150 mis off
The belonging sunrise time was charted in the
(American) Nautical Almanac (an Air Almanac was
not issued for the year).
Lat 00 deg LMT 0600
July 2,3,4 U.L.H.
Lat 10 deg N LMT 0543
For 00009'-N we find LMT 0600 - 9/600 x 17m =
0559:45 LMT. By adding the West longitude in time
units (I Ih55m08s) it is found that Upper Limb Sunrise
for the Offset Course Shift was at 1754:53 GMT.”


( A navigator would never do the time computations that you did especially he would never use
GAT since the Nautical Almanac in 1937 used GMT for all the tabulations which were for GHA,
not right ascension, and Noonan said himself that:

 “I consider the development the Greenwich hour- angle idea the greatest contribution to the
science
of navigation since Sumner, and have used it exclusively since first published in the Air
Almanac.”  See:

https://sites.google.com/site/fredienoonan/resources/weems/weems-424-425.JPG?attredirects=0

What you are doing here is assuming that the plane was located at 178? 47' west and 0? 09' north
and then calculating the time that the sun would have risen at that location. We only have to look
at
the first part of that computation since the problem there carries through all the rest of your
computations. You looked at the “Sunrise- Sunset” table for July 2, 1937 (you actually must have
looked at a modern Nautical Almanac because there was no such table in the 1937 so Noonan
couldn’t have done the computation that you did, nor would he have wanted to.)  The tabulated
values are
only correct for the middle day of a three day period, which was July 3rd (in the modern almanac
you used. The 1937 almanac was not arranged in three day periods) and you found that sunrise on
the equator was at 0600 and that sunrise at 10? north was at 0543. You then did a straight line
interpolation between these two values to determine the time of sunrise nine NM north of the
equator
at 09' north as 0559:45.

“What is wrong with this picture?”

The most obvious problem is that the data in the table you used is only tabulated to the nearest
minute so no
matter what you do after that with this data it can never be more accurate than the level of the
original data. Based on your tabulated values, the sunrise on the equator (on July 3rd not the 2nd)
was
somewhere between 0559:30 and 0600:30 and the
sunrise at 10? north was somewhere between 0542:30 and 0543:30 with no way to know exactly
where within these ranges. The uncertainty range of plus and
minus 30 seconds in the original tabulated data must be applied to your calculated time so, using
your
method, the time of sunrise at 00? 09' north could have been anywhere between 0559:15 and
0600:15  yet you nail it exactly to
the
second at 0559:45. The “Sunrise- Sunset” table in the Nautical Almanac carries a warning that
when
interpolating for times of sunrise that: “rounding errors may accumulate to about 2 minutes.”
You ignored this warning.

Why is this important?

You may think that I am picking nits, but this 60 seconds of uncertainty in the time causes a 15
NM uncertainty in the derived longitude because the sun is traveling west along the equator at
900
knots, 15 NM per minute. All of your subsequent calculations flow from this calculated time of
sunrise.
At the end of your computations you come up with an error in Noonan’s longitude of just 9 NM
so your
result is swamped by the actual uncertainty in your original calculation of the time of sunrise so
your calculation has
no significance. You also forgot that Itasca was making smoke that blew downwind much further
than the 9 mile error that you claim Noonan made.


Gary LaPook
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on May 27, 2011, 05:55:41 PM
Thank you Gary.  I actually understood most of that.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on May 29, 2011, 03:03:09 PM
G.Lapk  If you apply and work the formula for U.L. sunrise @ 178-47-W ; 00-09´-N , you find the very same sunrise time as by N.A.table. If you want it simpler , calculate central sunrise with the short formula (cos LHA = - tan d . tan L) and subtract 53´/ 13´.8 = 3m50s , in which 13´.8 is the sun´s rising velocity in time minutes , and you will again find the very same outcome , also to be found by H.O.208 , Table II. There is no reason to doubt that Noonan , after succesfully establishing position by the sunset fix near Nukumanu , would also be able to finish a sunrise fix before trying to find Howland.
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on May 29, 2011, 05:40:22 PM
G.Lapk  If you apply and work the formula for U.L. sunrise @ 178-47-W ; 00-09´-N , you find the very same sunrise time as by N.A.table. If you want it simpler , calculate central sunrise with the short formula (cos LHA = - tan d . tan L) and subtract 53´/ 13´.8 = 3m50s , in which 13´.8 is the sun´s rising velocity in time minutes , and you will again find the very same outcome , also to be found by H.O.208 , Table II. There is no reason to doubt that Noonan , after succesfully establishing position by the sunset fix near Nukumanu , would also be able to finish a sunrise fix before trying to find Howland.

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

That is true, if you calculate the time of sunrise for July 2, 1937 for the position you chose using the actual data in the Nautical Almanac and a calculator then you do find the time of sunrise to be very close to the time you calculated by using the incorrect method by use of the sunrise table. This is only a coincidence.

Using your method of using the sunrise table you will calculate the same exact time of sunrise, 5:59:45 local time at the position you chose of nine minutes north latitude and at every longitude on earth for the entire three day period of the tabulated sunrise value. However, if you do the actual computation you will find that the time of sunrise will vary by 32 seconds at that latitude during that period so you just got lucky that at the location you chose that the computed time worked out right.   

 But
this is only a coincidence and does not work for other longitudes and other days in the three day
period covered by the tabulated value in the Nautical Almanac table. For example, if they were
flying one day later, then the true altitude of the sun’s center at the same time and location would
have been -55.5' causing sunrise to occur ten seconds later at 5:59:55 and resulting in a 2.5' error in
longitude. If they flew two days later (still within the period of the tabulated sunrise table) the
sun’s center would have been at -58.1' causing sunrise to be delayed by 20 seconds so the sun would
nor have risen until 6:00:05 and resulting in a 5.1' error in longitude.

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

(This is the boring calculations and you can skip down to the next section if you choose.)

You calculated sunrise (center of sun 53' below the horizon) at 178° 47' West and 00° 09' North
latitude as 5:59:45 LMT using the sunrise table. By an amazing coincidence the actual
computation works out very close to that, I calculated -52.9' the same as your calculated -53'. But
this is only a coincidence and does not work for other longitudes and other days in the three day
period covered by the tabulated values in the Nautical Almanac table. For example, if they were
flying one day later, then the true altitude of the sun’s center at the same time and location would
have been -55.5' causing sunrise to occur ten seconds later and resulting in a 2.5' error in
longitude. If they flew two days later (still within the period of the tabulated sunrise table) the
sun’s center would have been at -58.1' causing sunrise to be delayed by 20 seconds and resulting
in a 5.1' error in longitude. That three day tabulation would be used for sunrises starting at 89° 56'
East on July 2nd and continuing until
the sunrise at the same longitude on July 5th.  At nine minutes north latitude and at 89° 56' east, at
5:59:45 LMT on July 2nd (0000 GMT July 2nd) the center of the sun was -51.1' meaning the sun
would have risen 8 seconds earlier and causing 1.9' error in longitude. Three days later (2400
GMT July 4th) at the same location (and using the same tabulation from the sunrise table, using
your method) the sun’s actual center was -59.0' meaning that the sun rose 24 seconds later than
you would have calculated and resulting in a 6.0' error in longitude. So you see your result was
just a lucky coincidence.

-------------------------------------------------
(Start reading again here.)



 

I also note that you have now changed your basic premise stated in your papers that Noonan could have just used the sunset and sunrise tables in the Nautical almanac since I have shown you (off list)  that the computation cannot be done this way. There are no instructions in Dreisonstok on how to use these tables in this unforeseen way nor have I found it in any edition of Dutton of Bowditch or in any of the flight navigation manuals that I have.

 

You might be able to use the tables in H.O. 208 to do that calculation but what makes you
believe that Noonan or any other flight navigator could do that? (By the way, how long did it take
you to work out that method?) There are certainly no instructions in H.O. 208 to show a
navigator how to make that computation. Nor is there any discussion of doing such a
computation in any of the flight navigation manuals or even in Bowditch or Dutton. Can you
point to any navigation manuals that instructs a navigator to make such a computation?


It is interesting discussing theoretical celestial navigation with you but your methods were never
taught to navigators so there is no reason to believe that Noonan just came up with your method
all on his own. You have really fallen in love with the sunrise observation but you won’t find that
method in navigation manuals. Can you point out a manual that teaches your method for finding
longitude?

This sunrise is only used as a way to introduce the basic concepts for finding longitude to
celestial navigation students but it is not used in practice. Even in the olden days before Sumner
and the “new navigation”, navigators used the time sight for finding longitude and took the
observation when the body was on the prime vertical, not at sunrise. Navigators were told not to
take low altitude sights for this purpose and I sent you excerpts from Bowditch, 1863 and 1914 and
from Wrinkles in Navigation, 1884, for your review but nobody used these methods to determine
longitude by Noonan's time, everybody used the simpler Sumner line (LOP.)  The reason that H.O. 208 and other “short
methods “ were developed was to simplify the calculations that a navigator had to do, not to
make them more difficult.
Remember, for a navigator this is drudge work and, especially for a
flight navigator, it is important to reduce the time required for the calculations and to reduce the
opportunities for math errors. To this end, navigators learn one method and stick with it
throughout their careers even as newer methods are developed.  Noonan said exactly this in his
letter to Weems. see page 425:

https://sites.google.com/site/fredienoonan/resources/weems/weems-424-425.JPG?attredirects=0

So there is certainly no reason to believe that Noonan would try to go back to what he may have
remembered from his high school trig class to develop and try out for the first time the  novel and
theoretical method that you advocate for finding longitude on this very critical navigation leg.

Gary LaPook
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on May 30, 2011, 02:34:41 PM
GLapk. In the 1930´s a well known problem in nav. textbooks was : "You see sunrise @ x-time. Determine your longitude" . And I repeat : why would Noonan be succesful operating a sunset fix (EJN-2011) , whereas next morning he would not be able to duplicate it for sunrise ? H.O.208 namely , by it´s Table II delivers a comfortable fashion to compute longitude by sunrise time : you observe sunrise U.L. and note GMTime.
By precomputed multiplication  tan declination with tan latitude you obtain cos LHA , reduce by Tab.II to LHA . Add GHA to LHA , subtract from 180 deg and you have the longitude , a conservative calculation for sea (later air-) navigators of the era. There are no by accident outcomes , easily checked by comparison of Table results with direct spherics. If you have computed for central sunrise and you need sunrise U.L. , you subtract 3m50s (not time eq. but time needed for sun to orbit sun from -53´ to 0´) and your time and longitude  to be reduced from marine sextant observation are established. Why would we learn it in an evening , whereas a professional navigator with full scan long period precomputation experience would not know it ?
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on May 31, 2011, 12:58:42 AM
GLapk. In the 1930´s a well known problem in nav. textbooks was : "You see sunrise @ x-time. Determine your longitude" . And I repeat : why would Noonan be succesful operating a sunset fix (EJN-2011) , whereas next morning he would not be able to duplicate it for sunrise ? H.O.208 namely , by it´s Table II delivers a comfortable fashion to compute longitude by sunrise time : you observe sunrise U.L. and note GMTime.
By precomputed multiplication  tan declination with tan latitude you obtain cos LHA , reduce by Tab.II to LHA . Add GHA to LHA , subtract from 180 deg and you have the longitude , a conservative calculation for sea (later air-) navigators of the era. There are no by accident outcomes , easily checked by comparison of Table results with direct spherics. If you have computed for central sunrise and you need sunrise U.L. , you subtract 3m50s (not time eq. but time needed for sun to orbit sun from -53´ to 0´) and your time and longitude  to be reduced from marine sextant observation are established. Why would we learn it in an evening , whereas a professional navigator with full scan long period precomputation experience would not know it ?

---------------------------------------------------
Mr. van Asten,

I have asked you before to give the titles of any flight navigation manuals that tell a flight navigator that calculating the time of sunrise is a desirable way to determine longitude and all you now come up with is;

"In the 1930´s a well known problem in nav. textbooks was : "You see sunrise @ x-time. Determine your longitude""

I also pointed out that a discussion of sunrise in basic navigation textbooks was only used as a way to introduce student navigators to the concepts of how longitude relates to time and that the use of sunrise is not the way longitude was actually determined by navigators in the real world, even back in the 19th century and certainly not in the 20th century. It appears that you may be referring to some beginner level basic navigation training text book used in school, not to navigation manuals actually used by navigators. It also sounds like you may possibly be referring to old basic navigation textbooks from the 19th century because longitude was not determined separately by 20th century navigators since the 20th century method was to determine lines of position. In the 19th century "time sights" were used (a very different procedure than a sunrise observation) for separately determining longitude but this was before the development of the modern line of position method used by Noonan and all 20th  century navigators for finding fixes.  Even in the 19th century, a discussion of sunrise in a basic navigation textbook was only a  way of introducing the concepts necessary for finding longitude to student navigators because even in the 19th century "time sights" were used, not sunrise observations. I also pointed out to you that a sunrise observation is a poor way to determine longitude because any error in the assumed latitude, when doing the calculation, results in an error in the longitude that you determine.

I have also pointed out to you another reason that a sunrise observation is not used for navigation is due to the large uncertainty in the refraction at low altitudes so that all the navigation texts and manuals, then and now, advise against taking low altitude sights.

The American Practical Navigator, Bowditch, H.O. 9, 1938 ed., (the standard navigation reference book of the U.S. Navy) has this to say about low altitude sights: "Under certain conditions of the atmosphere a very extraordinary deflection occurs in rays of light which reach the observer's eyes from the visible horizon, the amount of which is not covered by the normal corrections for pressure and temperature; on account of it, altitude less that 5° should be avoided." This advice is continued in more recent editions of Bowditch. Other examples, the 1888 through 1914 editions, said to avoid altitudes below 10°.
See: https://sites.google.com/site/fredienoonan/resources/american-practical-naigator-h-o-9-1914
https://sites.google.com/site/fredienoonan/resources/american-practical-navigator-1888



The 1937 Nautical Almanac and the 1937 edition of H.O. 208 (the navigation references used by Noonan) did not even have tables to allow the use of observations of less that six degrees above the horizon so could not even be used for a zero degree, sunrise observation. You just refuse to accept these facts. Off list I have asked you questions relating to the use of the refraction correction table and it is clear from your answers that you misunderstand how to use this table.


Navigation and Nautical Astronomy Dutton, 1934 ed. (the official textbook at the U.S. Naval Academy) states that due to the large unpredictable variations in refraction, that the time of sunrise can vary by TWO MINUTES which would cause an uncertainty of 30 nautical miles in a position determined by a navigator using your method for determining longitude by observing sunrise.
See: https://sites.google.com/site/fredienoonan/topics/refraction

H.O. 218, "Astronomical navigation Tables," first published in 1938, was a table of precomputed altitudes and azimuths for use by flight navigators and was an improvement on, and a replacement for, H.O. 208. Since all navigators knew not to take low altitude sights, the lowest altitudes tabulated in this more modern set of tables was 10°. For some reason you do not understand that a "sunrise sight" is nothing more than a zero degree altitude sight with all the uncertainties mentioned in the standard reference works. 

And now, only after I showed you that the method of calculating the time of sunrise that you published in your 2008 and 2011 papers by using the sunrise table in the Nautical Almanac, that were never intended for that purpose, and that navigators only use its approximate values for planning purposes, and would never think to use it in the manner that you described, you now have invented a new, esoteric, unintended use of the information contained in H.O. 208 to do this calculation. You may be a mathematician with plenty of time on your hands to conjure up novel ways to do trigonometric computations, but there is no reason to think that Noonan or any other navigator would attempt to do the same. There are no instructions in H.O. 208 itself or any other navigation manual describing your creative use of these tables. H.O. 208 was designed for one purpose only and that was to calculate lines of positions and the tables are organized and optimized for that one purpose and the instructions contained in H.O. 208 show only that use of the tables. Noonan said in his letter to Weems that he used H.O. 208 (Dreisonstok) method exclusively meaning he used the method in H.O. 208, not just the tables in it,  to calculate lines of position and he would have had no reason to try to deviate from his normal, practiced, and exclusive use of the H.O. 208 method to invent some esoteric use of these tables as you describe.

See: https://sites.google.com/site/fredienoonan/resources/weems/weems-424-425.JPG

The entire sections on finding longitude from the 1888 and 1914 editions of the American Practical Navigator are posted here:

https://sites.google.com/site/fredienoonan/resources/american-practical-navigator-1888

and

https://sites.google.com/site/fredienoonan/resources/american-practical-naigator-h-o-9-1914

There is no mention of using your sunrise method.

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

You have told me that you have over a hundred navigation texts in your library so please give us the titles of any

A.) flight navigation manuals that tell a flight navigator that calculating the time of sunrise is a desirable way to determine longitude;

B.) any 19th or 20th century texts that show using sunrise as a way to determine longitude;

C.) any 20th century texts, marine or flight, that show the calculation of sunrise to an accuracy of one second of time by use of the Nautical Almanac sunrise table;

D.) any 20th century texts, marine or flight, showing your new method of calculating the time of sunrise;

E.) any 20th century texts, marine or flight, showing how to use the tables in H.O. 208 to calculate the time of sunrise.

Gary LaPook


;

Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on May 31, 2011, 01:44:26 AM
GLapk. In the 1930´s a well known problem in nav. textbooks was : "You see sunrise @ x-time. Determine your longitude" . And I repeat : why would Noonan be succesful operating a sunset fix (EJN-2011) , whereas next morning he would not be able to duplicate it for sunrise ? H.O.208 namely , by it´s Table II delivers a comfortable fashion to compute longitude by sunrise time : you observe sunrise U.L. and note GMTime.
By precomputed multiplication  tan declination with tan latitude you obtain cos LHA , reduce by Tab.II to LHA . Add GHA to LHA , subtract from 180 deg and you have the longitude , a conservative calculation for sea (later air-) navigators of the era. There are no by accident outcomes , easily checked by comparison of Table results with direct spherics. If you have computed for central sunrise and you need sunrise U.L. , you subtract 3m50s (not time eq. but time needed for sun to orbit sun from -53´ to 0´) and your time and longitude  to be reduced from marine sextant observation are established. Why would we learn it in an evening , whereas a professional navigator with full scan long period precomputation experience would not know it ?


--------------------------------------------------------------
I didn't respond to you question. You asked:

"And I repeat : why would Noonan be succesful operating a sunset fix (EJN-2011) , whereas next morning he would not be able to duplicate it for sunrise ?"

The answer is that he didn't do a "sunset fix" either for the same reasons stated in my prior post. Your "sunset fix" is another invention of yours based again on your lack of understanding of how flight navigation is actually done.  For a more detailed answer see my prior post.

Gary LaPook
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on May 31, 2011, 06:59:00 AM
This has been an educational exchange but I think Gary LaPook has adequately demonstrated that Mr. van Asten's speculation about Noonan's navigation on the Lae/Howland flight is founded more upon his own creativity than upon any documented practice by aerial navigators in general or by Fred Noonan in particular. It's pretty clear that no one is going to change Mr. van Asten's mind but I hope he will at least accept that this forum does not find his arguments convincing.  We need to move on.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on May 31, 2011, 12:53:51 PM
G.Lapk. Yes , but my question was : why would the navigator succesfully establish position by a sunset running fix , whereas 10 1/2 hours later , with only the sun available , he would at random fly to destination , RDF failing , without an as good as possible sunrise position check before going inbound ?

I btw herewith leave this forum , I find the reactions , mostly upon questions of others I have replied to , too hostile to continue contributions.
Title: Re: Why 10AM from Lae?
Post by: Alex Fox on May 31, 2011, 03:34:03 PM
I found the exchange to be enlightening and incredibly civil.  I don't see anything that could even be misconstrued as hostile.  Unless bolding text is the navigational equivalent of cursing at someone.

Anyway, this is way out of my league in every academic sense, but I still find it very interesting.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 01, 2011, 02:07:45 AM
G.Lapk. You discard the possibility that Noonan established position by a sunrise/sunset fix as in EJN-208/2011,using the sextant for observation. To my surprise however , you published in NavList "Longitude by Sunrise" , Feb 05-2010 , that you have used the methodology yourself with very good results (0.1 nm) , using the U.L.sun. You did not observe from o/b of an A/c evidently , but the very same fashion was succesfully used from aloft by mrs.C.Lindbergh (LA to NY , 1930) ,Getty (1931) and Ellsworth crossing Antarctica (1935) and F.Chichester for finding the small islands Norfolk and Lord Howe in the Tasman Sea (1932). Did the radio communications stop after 2014 GMT because Amelia Earhart needed time to knock Noonan cold for punishing  hiim since he had slept during the entire journey ?
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on June 01, 2011, 06:39:38 AM

I thought you were leaving.

Did the radio communications stop after 2014 GMT because Amelia Earhart needed time to knock Noonan cold for punishing  hiim since he had slept during the entire journey ?

What makes you think that radio communications stopped after 2014 GMT?
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on June 01, 2011, 06:51:48 AM
G.Lapk. You discard the possibility that Noonan established position by a sunrise/sunset fix as in EJN-208/2011,using the sextant for observation. To my surprise however , you published in NavList "Longitude by Sunrise" , Feb 05-2010 , that you have used the methodology yourself with very good results (0.1 nm) , using the U.L.sun. You did not observe from o/b of an A/c evidently , but the very same fashion was succesfully used from aloft by mrs.C.Lindbergh (LA to NY , 1930) ,Getty (1931) and Ellsworth crossing Antarctica (1935) and F.Chichester for finding the small islands Norfolk and Lord Howe in the Tasman Sea (1932). Did the radio communications stop after 2014 GMT because Amelia Earhart needed time to knock Noonan cold for punishing  hiim since he had slept during the entire journey ?

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

My post was the 14th post on a thread started by a professional shipboard navigator who was
criticizing an article in Ocean Navigator Magazine entitle  “Longitude by Sunrise” which is why
the thread had that name, I wouldn’t have used that title.

See the first post here:

http://www.fer3.com/arc/m2.aspx?i=111750&y=201002

Nine people posted to this thread and if you read them all you will find disapproval of the
method and caveats about its lack of  accuracy. It was generally agreed that due to the inherent
inaccuracy in the method that it might be useful as an emergency, or lifeboat method.

Here is the link to my post that you mis-characterize as my determining longitude.

http://www.fer3.com/arc/m2.aspx?i=111795&y=201002

If you reread it you will see that it discusses the derivation of normal lines of position from zero
altitude sights taken on a ship with accurate heights of eye (24 and 26 feet) and special
corrections for non-standard temperature and pressure. Here is the first paragraph:

“Zero altitude sights (Hs = 0) can work out well but the problem is that
you don't know if this sight is an accurate one or an inaccurate one due
to the vagaries of refraction that the observer won't know about.
Because of this you have to allow a larger uncertainty band around any
LOP taken this way. I have taken such observations in flight and they
work out well considering the lower accuracy inherent in flight
navigation and I have carried a table in my wallet for 30 years for this
purpose, it is posted here:”

You do see the mention of “LOP” in the paragraph and the word “longitude” does not appear in
my post.  You cite one observation that resulted in a 0.1 NM error in the derived LOP but you
left out the other two observations that had errors of 1.8 and 2.3 NM. I never got this level of
accuracy for zero altitude LOP observations from an airplane, they were usually in the 10 to 20
NM range, and, in case you missed this point, these were normal LOP observations, not
observations for longitude. I would not have been able to achieve even this level of accuracy
without the modern refraction and dip tables applicable to airplanes that were not available until
1951.

 I ended the post with:

“These all provide useful LOPs  keeping in mind the larger band of
uncertainty.”

You should read the rest of the posts on that thread and you will see that the other guys got worse
results.
See: http://www.fer3.com/arc/sort2.aspx?y=201002su




You should read my other two posts on this thread in which I lay out all the problems with the
inherent inaccuracy in these types of sights for LOPs.

http://www.fer3.com/arc/m2.aspx?i=111779&y=201002

http://www.fer3.com/arc/m2.aspx?i=111780&y=201002



It is interesting that you list some early aviators implying that they used your sunrise method, do
you have any sources for this claim? Ellsworth used a bubble sextant, Lindbergh used a Pioneer
bubble sextant (there is a photo of his navigation equipment in Weems, 1938). I have analyzed
Chichester’s navigation extensively and he used a marine sextant to take five sextant
observations on the New Zealand to Norfolk Island flight, all were in the range of 23° 12' to 50°
50'. On the next leg to Lord Howe Island he also took five observations, all in the range of 23° 48'
to 53° 42'.  So contrary to your claim, none of his observations were anywhere near a zero altitude
or a sunrise sight.

Gary LaPook
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on June 01, 2011, 07:06:13 AM
G.Lapk. You discard the possibility that Noonan established position by a sunrise/sunset fix as in EJN-208/2011,using the sextant for observation. To my surprise however , you published in NavList "Longitude by Sunrise" , Feb 05-2010 , that you have used the methodology yourself with very good results (0.1 nm) , using the U.L.sun. You did not observe from o/b of an A/c evidently , but the very same fashion was succesfully used from aloft by mrs.C.Lindbergh (LA to NY , 1930) ,Getty (1931) and Ellsworth crossing Antarctica (1935) and F.Chichester for finding the small islands Norfolk and Lord Howe in the Tasman Sea (1932). Did the radio communications stop after 2014 GMT because Amelia Earhart needed time to knock Noonan cold for punishing  hiim since he had slept during the entire journey ?
---------------------------------------------------------------

Further response:

Here is what I posted about the article in Ocean Navigator Magazine about that author's idea that a navigator could use the van Austen method of using a sunrise/sunset observation should be used to determine longitude:

"I always start with the proposition that you always know where your are, e.g. on the planet earth, in the middle of the ocean, etc. The real question is "do you know where you are to the precision needed at the time?" If you are in the middle of the ocean it may be sufficient to know only that you are "in the middle of the ocean." As you approach dangers then the needed level of precision increases to the point that you need to know where you are to within a few meters when entering a pass through a reef  at night. The position finding system basically utilizes additional information, as it becomes available, to increase the level of precision and thereby refine the position. Based on this, this method does add information and so improves the precision of the position. In some places it may provide the level of precision necessary but in others it can't. In the middle of the ocean it is adequate but nearing a hostile shore it isn't.

Looking at specifics. First, it states to use the lower limb when timing sunset when the table itself says to use the upper limb for this measurement. This may be just a typo. This error would make at least a 32' error in longitude.

The sunrise- sunset table only tabulates the times to the nearest whole minute meaning that the actual event could occur thirty seconds earlier or later. This would cause an error band 15' wide on the calculated longitude.

The times are tabulated for a three day period based on the middle day so have a built in inaccuracy for the other days. Just glancing at a random page in the table and comparing times on consecutive pages I found, at high latitudes, a change of 15 minutes in the three day period and even at 60° latitude a change of 8 minutes. There are probably larger changes than these on other pages. So using the tabulated times for the two days other than the middle day of the period it is quite likely to introduce a two minute of time error adding an additional 30' error in the calculated longitude. At 72° latitude this error could be, or exceed, 5 minutes causing a 75' error in the derived longitude.

The computation requires you to know your latitude to use to enter the table. The table is, in essence, a tabulation of the traditional "time sight." If you are not at one of the tabulated latitudes straight line interpolation between the tabulated values will also introduce an additional error since the time of sunrise and sunset doesn't vary this way but I haven't attempted to quantify the error introduced this way, but it is larger than zero.


In addition to these errors inherent in this method there are also the errors in the observation of the upper limb on the horizon, dip and non standard refraction. Looking at the refraction correction table in the N.A. shows up to a plus and minus error of 6.9' for non standard conditions which introduces a possible additional error band in the LOP of 13.8'. And in some instances the error could be much worse but far from land you will not see the resulting mirages that could tip you off if land were nearby. The error introduced in the derived longitude due to errors in the refraction correction (and dip, if not allowed for) can be much larger than the actual error itself. Except on two days of the year the actual LOP doesn't run directly north and south but is at right angles to the azimuth of the sun which varies with latitude and declination as is clear from an examination of Table 27 in Bowditch, Amplitudes. Because the errors in observation act at right angles to the LOP (along the azimuth to the sun) the error in the derived longitude will exceed the magnitude of these errors, increasing as the azimuth of the sun varies from straight east or west ( the amplitude) which at 60° latitude, for example, is 52.9°. For this case the error in longitude will be 66% larger than the error in the observation itself so the error band in the longitude from non-standard refraction (not counting extreme, mirage, conditions) increases from 13.8 minutes to 22.9'.

But, since to do this computation you must have the Nautical Almanac, why not just work the sight as a normal LOP with a sextant altitude of zero degrees? This eliminates the timing problems and the multiplication effect on the errors in the observation?"

To which I added:

I had written:

"The computation requires you to know your latitude to use to enter the table. The table is, in essence, a tabulation of the traditional "time sight." If you are not at one of the tabulated latitudes straight line interpolation between the tabulated values will also introduce an additional error since the time of sunrise and sunset doesn't vary this way but I haven't attempted to quantify the error introduced this way, but it is larger than zero."

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

I decided to do a trial computation to look at this factor. Using today's data, the time of sunset at 30 ° latitude is 14 minutes, 10 seconds earlier than at 20°. Using straight line interpolation for 25° latitude, as stated in the article, sunset should be 7 minutes and 5 seconds earlier but, in fact, it is 7 minutes and 24 seconds earlier, a difference of 19 seconds. So using straight line interpolation would cause an error of almost 5' in longitude. It is certain that there must be even larger differences for other dates and   latitudes and, therefor, larger longitude errors if using this method.

Gary LaPook

Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 03, 2011, 02:00:57 PM
Mr. Lapook,

You wrote here that computations I made ("invented") were generally beyond knowledge of of the era sea/air navigators. Certain calculations however , were for them as old as the hills , like computing the LHA (always of the true sun) and the GHA of a heavenly body. Strictly within these limits of skill we (and any navigator henceforth) can establish sunrise time , no N.A.listing ,no rounding , no formulae , in the roads of Howland as described in EJN-2008 / 2011 :

GHA @ 159-07-E                       071545 GAT     288-56-18
GHA @ 178-47-W      U.L.sun horizon       add      87-45-40
                                                                   ________
                                                                   201-10-38
                                           subtract from      360-00-00
                                                                   ________
In orbit travel of true sun                                 158-49-22

Divide by  15 deg / hr                                     10h35m17s

Add : GAT  of sunset  @ Nukumanu Fix     Add        7-15-45
                                                                    _______
GAT                                U.L. sun in horizon      17-51-02

Add   03m50s                      Equation of Time          03-50
                                                                    _______

GMT of sunrise U.L.                                           17-54-53
                                                                    =======

The sunset fix appears in detail in EJN-2011 , the sunset fix is recomputed  , in somewhat other terms as above , in EJN-2008.





 
                                                                   

Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 03, 2011, 03:01:30 PM
G.Lpk. Last sentence : ..the sunrise fix is recomputed ..





Title: Re: Why 10AM from Lae?
Post by: Monty Fowler on June 03, 2011, 04:01:59 PM
Mr. Van Asten, I'm thinking it's about time you broke out the popcorn and put the Ameila DVD into your player and just kicked back for awhile ... because, to me, the nits you're picking at, re-picking, kicking, stomping on and otherwise beating to death have gotten way, way less entertaining.

My 2 cents.
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on June 03, 2011, 07:05:46 PM
Mr. Lapook,

You wrote here that computations I made ("invented") were generally beyond knowledge of of the era sea/air navigators. Certain calculations however , were for them as old as the hills , like computing the LHA (always of the true sun) and the GHA of a heavenly body. Strictly within these limits of skill we (and any navigator henceforth) can establish sunrise time , no N.A.listing ,no rounding , no formulae , in the roads of Howland as described in EJN-2008 / 2011 :

GHA @ 159-07-E                       071545 GAT     288-56-18
GHA @ 178-47-W      U.L.sun horizon       add      87-45-40
                                                                   ________
                                                                   201-10-38
                                           subtract from      360-00-00
                                                                   ________
In orbit travel of true sun                                 158-49-22

Divide by  15 deg / hr                                     10h35m17s

Add : GAT  of sunset  @ Nukumanu Fix     Add        7-15-45
                                                                    _______
GAT                                U.L. sun in horizon      17-51-02

Add   03m50s                      Equation of Time          03-50
                                                                    _______

GMT of sunrise U.L.                                           17-54-53
                                                                    =======

The sunset fix appears in detail in EJN-2011 , the sunset fix is recomputed  , in somewhat other terms as above , in EJN-2008.





 
                                                                   



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

That's nice.

I guess that I should be impressed by your mathematical abilities except that in your two published papers you said that Noonan would have calculated the times of sunrise and sunset by the much simpler method of interpolation of the times in the Nautical Almanac sunrise/sunset tables. You have now had to invent this new, complicated method of computation after I demonstrated to you that your interpolation of the sunrise table method (and you were sure of that one and resisted for some time) doesn't work. I have over 40 editions of the American Practical Navigator, going all the way back to the first edition written by Bowditch in 1802. I scanned and sent to you excerpts from the 1863, 1888 and 1914 editions as examples showing that none of them show your sunset/sunrise method for finding longitude. I have reviewed all of my editions (I am not going to scan in any more of them) and, you'll have to take my word for this, none of them contain your sunrise/sunset method for determination of longitude or your newly invented way for calculating that time. They do contain other methods for determining longitude, time sights, lunar distances, eclipses of Jupiter's moons, lunar eclipses, charts of magnetic variation, etc., the list seems pretty complete so I am surprised I found no mention of your method that you claim was standard and known to all navigators. The American Practical Navigator has been the standard navigation reference book for American navigators since 1802. Noonan was an American navigator so we can expect that he would have been knowledgeable of it content. But, by the time he was practicing navigation, all of the longitude methods that I just mentioned  had become archaic and were no longer in use, having been replaced by the universal use of the LOP (Sumner line) so he would not even have used the time sight, which was the last method of longitude determination deleted from the American Practical Navigator.

In the past I have asked you to provide the books that you claim contain your methods and you have refused to do so, I have shown you mine but you haven't shown me yours. So, I am not going to continue this conversation with you until you do.

Gary LaPook
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on June 03, 2011, 07:45:49 PM
I'm thinking it's about time you broke out the popcorn and put the Ameila DVD into your player and just kicked back for awhile ...

I don't think Mr. van Asten has committed any offense that deserves being condemned to sit through that film.
Title: Re: Why 10AM from Lae?
Post by: Hilary Christine Olson on June 03, 2011, 10:01:49 PM
Actually Gary has earned respect He now has a full name not an abbreviated form. I have been quite reluctant to post as my first and last initials can imply a tag I only like in triplicate at Xmas !
Ho Ho Ho ! ;)
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 03, 2011, 10:39:10 PM
G.Lapk. As I told you , as soon as I am back home , I will go over the nav literature I have , I cannot have invented any nav theory or practice myself : when I started research in 1988 I knew zero on the subject.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 03, 2011, 11:06:20 PM
G.Lpk. There is no reason to be impressed by anything mathematic since the GHA/LHA listing is arithmetical ; may it be that time sight , or longitude by chronometer do not have , or no longer possess a paragraph in American Practical Navigator , that does not mean that the technique not existed resp. was dispersed among navigators circles , might it be as an emergency measure.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 03, 2011, 11:47:31 PM
G.Lapk. It may be so that interpolation by N.A. (or other) listing of sunrise time gave the exact (175453 GMT) outcome , accidentally , as compared with the formular result . If it so happened o/b of A/c the coincidence simply took place. It has no influence on any outcome of theory : the sunrise U.L. time is exact , only : if instead of using the bubble sextant @ sunset , the marine sextant was used , the navigator observed the visible sun of 175103 GMT , not the one of 175453 GMT for which the watch time was shifted to GMT 175843 . The navigation error (as of theory) is completely independent of time and position of A/c @ sunrise.
Title: Re: Why 10AM from Lae?
Post by: Monty Fowler on June 04, 2011, 08:42:33 AM
Mr. Van Asten - with all due respect - you have no idea, nor does anyone else, which sextant Fred Noonan used to take which sight, and when. You weren't there. The only two people who were are dead.  

Therefore, any theory constructed on the assumption of which sextant was used, introducing or not introducing an error, is, in the simplest and most basic of engineering terms, a WAG*.

My polite 2 cents.

P.S. to Ric - Amelia wasn't that bad ... if you were willing to, ummmm, suspend belief and not get hung up about things like facts for a couple of hours.  ;D




P.P.S - *WAG - wild-assed guess. And yes, I have seen it in official memos *laughs*
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 05, 2011, 12:22:50 AM
Mt.Fwr . I suppose you were on Gardner when the aircraft landed there after a 200 mls southwards navigation fault of which you have documents ?  Any theory developed must be first ,that is on short term , be consistent : not any flaw of computation must be present and there is no contradiction with logic. The  relevancy (does it match things that happened) is of second line importance and dependend of further research. If this rule (consistency-relevancy) is trespassed you will always see that opponents try ,with many words , undermine the statements of theory , and when not succesful , they turn vexed and end with the clincher "pure speculation" . For complex incidents like Earhart´s , it´s background containing mathematical implications ,any theory without quantitative outcomes is useless.
Title: Re: Why 10AM from Lae?
Post by: Martin X. Moleski, SJ on June 05, 2011, 05:45:29 AM
... any theory without quantitative outcomes is useless.

Please note well that the statement quoted above is a theory without any quantitative outcomes.

It is a pure, non-mathematical, philosophical assertion that does not meet the standard set in it.

It is therefore, in its own terms, "useless."

One of the fundamental laws of computation is "Garbage in, garbage out."

It certainly seems to me that your computations begin with a whole host of assumptions that are not self-evident and that are not derived from self-evident truths.  If your premises are correct, then your conclusions ("quantitative outcomes") should be correct.

I doubt that your premises are correct.  Strict calculations based on nonsense are nonsense.
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on June 05, 2011, 08:36:13 AM
Strict calculations based on nonsense are nonsense.

And theories that can't be tested are nothing more than intellectual masturbation.
Title: Re: Why 10AM from Lae?
Post by: Martin X. Moleski, SJ on June 05, 2011, 09:32:13 AM
Strict calculations based on nonsense are nonsense.

And theories that can't be tested are nothing more than intellectual masturbation.

And that line is a theory that can't be tested, so ...   ;)
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on June 05, 2011, 10:45:52 AM
And that line is a theory that can't be tested, so ...

...contributors to this thread are in danger of going blind?
Title: Off-Topic
Post by: Zach Reed on June 05, 2011, 12:28:56 PM
On one of the forum threads over the past year, I saw a discussion on whether it was possible for AE/FN to send radio signals if the plane was floating. I think the point in question was whether they had to crank an engine to send signals.

I sort of skimmed past the conversation at the time, because the idea of them floating around in a plane sending radio signals sounded hilarious...


but its kind of struck my curiousity now. Does someone remember where that thread was?
Title: Re: Why 10AM from Lae?
Post by: Monty Fowler on June 06, 2011, 11:11:45 AM
Well ... I was trying to be polite by suggesting he kick back and watch Amelia. If it's as bad as Ric says, are we all in danger of ... going blind? 
Title: Re: Off-Topic
Post by: Ric Gillespie on June 06, 2011, 11:32:23 AM
On one of the forum threads over the past year, I saw a discussion on whether it was possible for AE/FN to send radio signals if the plane was floating. I think the point in question was whether they had to crank an engine to send signals.

The plane could not transmit if afloat because critical elements of the radio system would be underwater water.
Title: Re: Off-Topic
Post by: Martin X. Moleski, SJ on June 06, 2011, 12:55:53 PM
... the idea of them floating around in a plane sending radio signals sounded hilarious ...

I don't think it was a thread in its own right.  I'll go start one, perhaps, so that we have a ready reference.

At any rate, Ric gave the short answer.  Here is Bob Brandenburg's research paper on the topic,  "Bombing the Bridge to the Marshalls,"  (http://tighar.org/Projects/Earhart/Archives/Research/Bulletins/50_HillPaper/50_HillPaperCritique.htm) with contemporary sources to back up his claims.
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on June 08, 2011, 11:54:14 PM
G.Lpk. There is no reason to be impressed by anything mathematic since the GHA/LHA listing is arithmetical ; may it be that time sight , or longitude by chronometer do not have , or no longer possess a paragraph in American Practical Navigator , that does not mean that the technique not existed resp. was dispersed among navigators circles , might it be as an emergency measure.

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

Well, I would think it pretty amazing that if your sunset method was well known among navigators that no one ever thought to include your sunset method in any of the editions of the American Practical Navigator since 1802 through 2002, two hundred years of publication since it designed to be comprehensive and is the definitive reference navigation text in the U.S.

gl
Title: Re: Why 10AM from Lae?
Post by: Gary LaPook on June 09, 2011, 12:07:45 AM
Mt.Fwr . I suppose you were on Gardner when the aircraft landed there after a 200 mls southwards navigation fault of which you have documents ?  Any theory developed must be first ,that is on short term , be consistent : not any flaw of computation must be present and there is no contradiction with logic. The  relevancy (does it match things that happened) is of second line importance and dependend of further research. If this rule (consistency-relevancy) is trespassed you will always see that opponents try ,with many words , undermine the statements of theory , and when not succesful , they turn vexed and end with the clincher "pure speculation" . For complex incidents like Earhart´s , it´s background containing mathematical implications ,any theory without quantitative outcomes is useless.

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

OK, I have another theory then that should satisfy you. A flying saucer from Mars visits the Earth on July 2, 1937 and pulls Earhart's plane into the flying saucer and then returned to Mars with the Electra, Noonan and Earhart inside.  This theory is "consistant"  and there is no contradiction with logic so this theory is as good as yours based on your standard. It is also "relevant" as it does explain the disappearance.

gl
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 09, 2011, 08:07:57 AM
G.Lpk. There is no reason to be impressed by anything mathematic since the GHA/LHA listing is arithmetical ; may it be that time sight , or longitude by chronometer do not have , or no longer possess a paragraph in American Practical Navigator , that does not mean that the technique not existed resp. was dispersed among navigators circles , might it be as an emergency measure.

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

Well, I would think it pretty amazing that if your sunset method was well known among navigators that no one ever thought to include your sunset method in any of the editions of the American Practical Navigator since 1802 through 2002, two hundred years of publication since it designed to be comprehensive and is the definitive reference navigation text in the U.S.

gl


It was possibly not known to everyone , or it was deleted from specific handbooks , it nevertheless appeared in maritime nav manuals from which I learned it. Important is that it was known by F. Noonan , since he used it near Nukumanu : there , only the sun was available , for the exact recomputation see EJN-2011 .
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 09, 2011, 08:23:49 AM
Mt.Fwr . I suppose you were on Gardner when the aircraft landed there after a 200 mls southwards navigation fault of which you have documents ?  Any theory developed must be first ,that is on short term , be consistent : not any flaw of computation must be present and there is no contradiction with logic. The  relevancy (does it match things that happened) is of second line importance and dependend of further research. If this rule (consistency-relevancy) is trespassed you will always see that opponents try ,with many words , undermine the statements of theory , and when not succesful , they turn vexed and end with the clincher "pure speculation" . For complex incidents like Earhart´s , it´s background containing mathematical implications ,any theory without quantitative outcomes is useless.

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

OK, I have another theory then that should satisfy you. A flying saucer from Mars visits the Earth on July 2, 1937 and pulls Earhart's plane into the flying saucer and then returned to Mars with the Electra, Noonan and Earhart inside.  This theory is "consistant"  and there is no contradiction with logic so this theory is as good as yours based on your standard. It is also "relevant" as it does explain the disappearance.

gl

And better : they were jettisoned over 174-31-W / 04-40-39-S
Title: Re: Why 10AM from Lae?
Post by: david alan atchason on June 09, 2011, 10:35:35 AM
Quote
The plane could not transmit if afloat because critical elements of the radio system would be underwater water.

I certainly am not arguing that I know better than the experts. I completely agree that as the diagrams of the plane show, any transmissions from the floating plane would be hilarious. But what about the alleged statement of George Putman that an auxiliary battery was installed in the cockpit for emergency? If that's all that was done, and no provision was made for it to power an emergency radio, or to be hooked up somehow to their factory installed radio, that would be hilarious, too. (Zach, no offense, I'm just having fun with the word hilarious.) Maybe the battery hit Fred in the head during a rough landing. So was George Putnam talking through his hat?
But it doesn't matter. Say AE did land on Niku. The Japs have several ships nearby. It only takes them 3 days to find her. They have all the equipment they need to drag the plane off the reef, because they are prepared. The Itasca is off looking to the NW. Yes, a few parts are broken off dragging the plane, maybe a landing gear, but they pick up all the pieces they can find and off they go with AE and FN captured. Yes, they  desperately want that plane that they suspect could be a spy plane.
Title: Re: Why 10AM from Lae?
Post by: Ric Gillespie on June 09, 2011, 12:15:37 PM
I'm sorry, but this nonsense has gone on long enough.

But what about the alleged statement of George Putman that an auxiliary battery was installed in the cockpit for emergency?

Putnam made no such statement.  If you disagree cite your source. If your source is Goerner's book, check the sources Goerner cites in his footnotes - no, wait, his book has no footnotes.  Goerner's 45 year-old book is full of bad information and you're swallowing it hook, line and sinker.

Say AE did land on Niku. The Japs have several ships nearby.

Really?  What ships?  Where were they? Cite your sources.

It only takes them 3 days to find her. They have all the equipment they need to drag the plane off the reef, because they are prepared.

How do you know that? Cite your sources.

The Itasca is off looking to the NW. Yes, a few parts are broken off dragging the plane, maybe a landing gear, but they pick up all the pieces they can find and off they go with AE and FN captured. Yes, they desperately want that plane that they suspect could be a spy plane.

This kind of unsupported blather is pointless and adds nothing to the discussion.  If you wish to contribute to this forum you'll have to do what the rest of us do and support your ideas and opinions with hard facts.  Otherwise I will remove your postings.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 09, 2011, 11:15:40 PM
G.Lpk. There is no reason to be impressed by anything mathematic since the GHA/LHA listing is arithmetical ; may it be that time sight , or longitude by chronometer do not have , or no longer possess a paragraph in American Practical Navigator , that does not mean that the technique not existed resp. was dispersed among navigators circles , might it be as an emergency measure.

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

Well, I would think it pretty amazing that if your sunset method was well known among navigators that no one ever thought to include your sunset method in any of the editions of the American Practical Navigator since 1802 through 2002, two hundred years of publication since it designed to be comprehensive and is the definitive reference navigation text in the U.S.

gl


It was possibly not known to everyone , or it was deleted from specific handbooks , it nevertheless appeared in maritime nav manuals from which I learned it. Important is that it was known by F. Noonan , since he used it near Nukumanu : there , only the sun was available , for the exact recomputation see EJN-2011 .

Possiby since it is the Practcal Navigator handbook ?  mr.Noonan must have known the fashion since he applied it @ sunset @ 27 miles off Nukumanu.
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 10, 2011, 10:18:09 AM
G.Lpk. There is no reason to be impressed by anything mathematic since the GHA/LHA listing is arithmetical ; may it be that time sight , or longitude by chronometer do not have , or no longer possess a paragraph in American Practical Navigator , that does not mean that the technique not existed resp. was dispersed among navigators circles , might it be as an emergency measure.

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

Well, I would think it pretty amazing that if your sunset method was well known among navigators that no one ever thought to include your sunset method in any of the editions of the American Practical Navigator since 1802 through 2002, two hundred years of publication since it designed to be comprehensive and is the definitive reference navigation text in the U.S.

gl


I tried ( by "Practical Celestial Navigation" , S.P.Howell) and agree , by correcting NA listings for latitude and position difference from centre of time zone (APN method) , the outcomes do not sufficiently follow the by formula(e) precise time to seconds . This would say that mr.Noonan acquired his sunrise time from his sunset time and coordinates , having these precomputed by H.O.208 , Tab.II. There is also a manual "Emergency Navigation" in my library , I will consult that later.

Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 11, 2011, 10:56:48 AM
More importantly, the Itasca could have added her powerful searchlight which Amelia could have easily seen (before the ‘grey-of-dawn’) for 100NM or more (123NM @ 10K alt., clear night) depending on aircraft altitude and availability of clouds above Itasca to illuminate.

I was thinking about exactly this the other day.  The problem is that if they started the flight later in the day and missed seeing the searchlights they would have to continue on their path and wait for dawn (which would be about another hour or so away). ...

So far as I know, TIGHAR has not found a document from 1937 explaining the actual rationale for the 0000 GMZ takeoff from Lae (10:00 AM local time). 

What we do have evidence of is the expected time of arrival calculated before the takeoff:

"Finally, just before 8:00 PM aboard Itasca, official notification of Earhart’s departure arrived from Lae, via Samoa: 'Urgent, Black, Itasca . . . Amelia Earhart left Lae at 10 AM local time July 2nd. Due Howland Island 18 hours time.' This information presented a new picture. The plane had left Lae two hours earlier than previously reported, and the eighteen-hour time-en-route estimate indicated that Earhart anticipated lighter headwinds than predicted in the most recent forecast. Itasca should now expect the plane to arrive at around 6:30 AM" (Finding Amelia, p. 85).

From telegrams it is known that several takeoff times have passed in review. Leaving the runway at your standard time zero hours is of practical importance for DR since it averts continuously reckoning backwards to non-zero time points. To reach the Greenwich anti meridian at exact sunrise is imho no option , since sunrise o/b of an aircraft is extremly dependent of the groundspeed which is for long range flights impossibly predictable in anticipation (Nukumanu , e.g. was reached with 44 minutes delay due headwinds stronger than from forecast).


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

It appears that the 10 am takeoff was pretty random and not linked to navigational considerations. Although this time provided a convenient time to be approaching Howland, just shortly after being able to obtain a star fix and with the sun available for final approach (at least as a backup) , prior radiograms from Earhart had announced other, different, departure times. As further proof that having a recent star fix was not a consideration,  we only have to look at the planned Hawaii to Howland flight. They had planned to depart at 11pm Hawaii time (0930 Z) which would have put them at Howland at about 2100 Z, 9:30 am Itasca time. They actually attempted the takeoff at 5:40 am Hawaii time ( 1610 Z) so would have arrived at Howland at about 0340 Z, 4:10 pm Itasca time with no opportunity for star or moon fixes.

Gary LaPook


July 1 (as from documents) by comparison of Adelaide time signal , chronometer was 3 sec slow , ultimately on July 2 , 08 am , the time signal of Saigon was received upon which crew decided departure @ 1000 LZT , 0000 GMT .
Title: Re: Why 10AM from Lae?
Post by: h.a.c. van asten on June 11, 2011, 11:19:22 AM
There is no indication that Noonan requested any information about Nauru. The cable mentioning the new light appears to have been simply a courtesy appended to a weather report.

The "Lights in sight ahead" report is from a letter by T.H.Cude , 1937 Nauru director of police , to F.X.Holbrook claiming that the word "Lights" not "ship" have been heard in the Earhart transmission on 3105 kcs.

The original source is a State Department telegram from Sydney, Australia dated July 3m 1937, which reads: “Amalgamated Wireless state information received that report from ‘Nauru’ was sent to Bolinas Radio ‘at 6.31, 6.43 and 6.54 PM Sydney time today on 48.31 meters (6210 kHz), fairly strong signals, speech not intelligible, no hum of plane in background but voice similar that emitted from plane in flight last night between 4.30 and 9.30 P.M.’ Message from plane when at least 60 miles south of Nauru received 8.30 P.M. Sydney time, July 2 saying ‘A ship in sight ahead.’ Since identified as steamer Myrtle Bank sic which arrived Nauru daybreak today."

Unless Mr. Cude  produced the actual radio log for that night, the contemporary written record (the State Dept. telegram) trumps his 20+ year-old recollection.

When Earhart (as from documents) asked by telegram to Nauru for weather conditions , the reply contained additionally that industrial lights would be switched on , and a tower beam @ 560 ft above sea level (erroneously printed in telegram "5600 ft") , visible from ships 34 mls off , would burn . Optical range from 8,000 ft altitude was in theory ca.137 mls.
Title: Re: Why 10AM from Lae?
Post by: Tim Gard on April 05, 2013, 07:44:00 AM
I appreciate the input from all posters to this thread. It's been very informative.

Like the initial poster, I saw Bowen's statements about the Lae - Howland leg in Linda Finch's The Final Hours, Amelia Earhart's Last Flight.
 
Though point X may not have been the most accurate fix, it was a reference that  Bowen considered worthwhile.

In Mercy Mission (the docu-drama) they count the number of knuckles on the pilots' hands between the sun and the horizon to establish flight 771 being to the west of (flight 308).
Their altitudes were different (zero feet versus flight level 35).

Later they use differences in the noted time of sunset to establish 771's position relative to Auckland.

Title: Re: Why 10AM from Lae?
Post by: JNev on November 30, 2014, 06:01:34 AM
And that line is a theory that can't be tested, so ...

...contributors to this thread are in danger of going blind?

Perhaps, or at least growing hair on the medulla.

Sorry, stumbled across this looking for stuff on the lights at Nauru and couldn't pass that up.  ::)