Advanced search  
Pages: 1 ... 33 34 [35]   Go Down

Author Topic: The flight plan, magnetic course, headwinds.  (Read 349480 times)

Gary LaPook

  • T5
  • *****
  • Posts: 1624
Re: The flight plan, magnetic course, headwinds.
« Reply #510 on: August 09, 2012, 04:09:00 PM »



Don't be too hard on poor Mr. Balfour, after all, he was just the person who heard what he heard of the Morse code "dahs" and "dits" coming through the aether from Nauru. Remember, "it takes two to tango" and there is no reason to place the blame on Balfour since it is more likely that it was a poorly sent transmission by the Nauru operator. Telegrapher's errors were fairly common in that era, poor sending (the sending operator's "fist"), simply extending the the timing slightly of the dots, dashes, and spaces (the length of each dot and the spaces between them is only 0.03 seconds, THREE-ONE HUNDRETHS OF A SECOND, for code sent at the fairly standard thirty words per minute of skilled operators) can change one letter into two different letters or characters plus static and noise on the frequency. The omitted "6" in the longitude of Nauru and the repeated extra "0" in the altitude of the light were almost certainly made by the sender as adding a character or dropping a character are fairly common errors in sending Morse. But this does not affect the fact that the standard notation used by Balfour and others of that era (there are many other examples of this) to use dots to separate degrees from minutes and that is obvious in this case since ".32" and ".55" accurately states the minutes in the position of Nauru and so proves that the 0718 Z position report was in degrees and minutes. We have discussed this before here. I remember a case we studied in law school on this point. A principal had sent a telegram to his agent, "buy 10,000 tons of ....(some comodity)" and the message delivered to the agent said "buy 100,000 tons of ....". The market dropped for that commodity and the man lost a great deal of money on the extra 90,000 tons of stuff so he sued the telegraph company. He lost because the court held that this was a common type of transmission error and, that  because of this, that if the sender needed to be sure that his message had been sent accurately, the tariffs of the telegraph company provided that, for an extra charge, the telegram would be transmitted back from the destination to the sender so that the sender could check the accuracy of the telegram as delivered. The principal had not paid this extra fee and the tariffs disclaimed liability for this type of transmission error without that extra fee. This was one of the reasons that telegraphic codes were developed because the code word for "10,000" might be "thasius" and the code word for "100,000" might be  "tibullis", no way to make that type of error when using a code. See attached excerpt of the ABC Code.


Here is an example of how telegrapher's errors occur. Morse code consists only of "dots" and "dashes." The dots are one unit long and the dashes are three units long. The space between each element (the dots and dashes) in a letter are also one unit long and the space between letters are three units long. When sending at 30 words per minute, each unit of time is 0.03 seconds, three-one-hundreths of a second. Let's say the word "rough" is to be transmitted. The first letter is "R" which in Morse code is "dot-dash-dot," with .03 seconds between each element. If, however, there is the minutest of extra time between the first dot and the dash (say, .046 seconds, half way between the single unit for the space between elements in a letter and the three units between letters, only 15 thousandths of a second too long) then the receiver will interpret that lone beginning dot as a separate letter, the letter "E," since the Morse code for the letter "E" is a single dot. The receiver will then hear the remaining "dash-dot" as the letter "N." The receiver will end up taking down the word as "enough" instead of the correct "rough."

gl
« Last Edit: August 09, 2012, 07:38:48 PM by Gary LaPook »
Logged

Gary LaPook

  • T5
  • *****
  • Posts: 1624
Re: The flight plan, magnetic course, headwinds.
« Reply #511 on: August 10, 2012, 03:11:56 AM »


The 0718 Z report was not in Morse code, Earhart was speaking on the radio and Balfour took down what she said and placed the standard "." to separate the degrees from the minutes. Earhart did not say, "four point three three degrees south" she said either "four degrees thirty three south" or, more likely, she said "four (slight pause) thirty three south." This is also corroborated by the 0519 Z position report in which the longitude was recorded as "150.7 east" which everybody knows is impossible. But "157° east" is very reasonable given her ground speed. Earhart simply said "longitude one five seven east" and Balfour thought he heard a slight pause between the "5" and the "7" and so placed his dot there.

gl

See more prior discussions of this point here.

gl
Logged

Gary LaPook

  • T5
  • *****
  • Posts: 1624
Re: The flight plan, magnetic course, headwinds.
« Reply #512 on: August 14, 2012, 12:28:46 AM »

Quote
The only way that they could identify being on the 157/337 line is that they got at least one, and probably several, observations of the sun in the vicinity of Howland.
I would suggest that they were simply following a magnetic heading.

The 157° - 337° was a true course not a magnetic heading and is the azimuth of the LOP established by an observation of the sun any time within an hour of sunrise. How do we know it is not a magnetic heading? That's easy, because if it were a heading then the numbers would not be reciprocal but would differ from being reciprocals by twice the wind correction angle. With a wind out of the east at 25 knots and a true airspeed of 130 knots the wind correction angle to maintain a true course of 157° was 10.2° left making the true heading 146.8°.  Now turn around and fly a true course of 337°. The wind correction angle is now 10.2° right making the true heading 347.2°. Note that these numbers differ by 200.4 degrees, the 180° for a reciprocal plus 20.4° which is twice the wind correction angle.  You then apply the variation of 9.5° east and the magnetic heading for the first leg becomes 137.3° and 337.7° for the second leg and these numbers also differ by 200.4 degrees, they are not reciprocals.
gl
« Last Edit: August 14, 2012, 04:19:39 AM by Gary LaPook »
Logged

Gary LaPook

  • T5
  • *****
  • Posts: 1624
Re: The flight plan, magnetic course, headwinds.
« Reply #513 on: August 14, 2012, 03:35:42 AM »


A couple of other points about this possible mistake:

•   Wouldn't AE have been worried by the lack of radio contact with the ship in the night?  No. She already knew the originally agreed radio protocol was made useless by the fact that the ship had no HF reception equipment.  She had sent a telegram trying to change that protocol, but she knew it probably hadn't reached the ship yet.  She wasn't expecting radio contact.
•   Could she have mistaken the 400-foot Myrtlebank for the 150-foot Ontario?  That begs further questions: how good was her ship identification at night?   How much did she even know about what the Ontario was supposed to look like?  Bear in mind she presumably didn't know that the Myrtlebank was in the area.
•   How had they missed the Ontario earlier?  Well, the Ontario's log mentions cloud cover from 20 to 40%; what's more, it wasn't precisely at the latitude she seems to have been expecting.  All too easy to miss.
•   What happens after they come up short? They end up flying the LOP south, and if they're starting short - from west of Howland - that brings them, as it happens, very nicely to Gardner.
•   Finally, this makes sense of the conjecture that some of the numbers in Betty's notes represent the Ontario's intended position.  If Fred is out of action, and AE can't take or doesn't trust her own measurements of where they are, the Ontario is still AE's "last known good" navigational position.  Not so good, in reality.

Any thoughts?
Your post brings up a number of points to discuss. You correctly point out that IF they mistook the Myrtlebank for the Ontario, and IF they started a new dead reckoning from the coordinates they had been given for the Ontario, and IF they used this position as the starting point for calculating their ground speed with the sunrise line of position as the ending point for the ground speed calculation, and IF they got no celestial observations between those points, and IF they got no additional sun observations after the sunrise observation then they would have advanced the sunrise LOP an incorrect distance so that when they intercepted that advanced LOP and followed it they would not have flown over Howland. I have attached a file with several illustrations to help you follow along.

gl
Let's look at those "IFs," starting with the first one, did they mistake the Myrtlebank for the Ontario? Not likely, based on the extremely high ground speed that would have been necessary to have reached the Myrtlebank by the 1030 Z radio report. There is another reason that this is unlikely, that is because the Ontario was transmitting the letter "N" in Morse code from 1010 Z to 1015 Z, just 15 minutes prior to the ship being spotted. Using the RDF made it very simple to find the Ontario. Since the signals ended only 15 minutes prior to their spotting the ship, they only had to fly the heading indicated by the RDF for about 30 NM which means that they were very unlikely to pass more than 3 NM from the Ontario.
This also solves the mystery that has had many of us scratching out heads, why would Earhart leave Lae to fly all the way to Howland when she could not get a positive test result showing that the RDF was working when she did the test flight the day before leaving Lae. It now makes sense that Noonan just said "we will test the RDF when we get within range of the Ontario and if we don't get a bearing that leads us to that ship then we can still turn around and return to Lae or Rabaul since the Ontario is well short of the point of no return."
There has been some question as to whether Ontario was transmitting the requested signal.

The following messages concerned Ontario whose call sign was NIDX.

6-23-37 Black to Earhart:

FOLLOWING FOR AMELIA EARHART PUTNAM AT DARWIN OR BANDOENG JAVA VIA AMALGAMATED WIRELESS - ONTARIO NIDX TRANSMITTER 500 WATTS FREQUENCY RANGE 195 TO 600 KCS EITHER CW OR MCW. NO HIGH FREQUENCY EQUIPMENT ON BOARD.

6-26-37 Earhart to Coast Guard:

SUGGEST ONTARIO STANDBY ON 400 KCS TO TRANSMIT LETTER N FIVE MINUTES ON REQUEST WITH STATION CALL LETTER REPEATED TWICE END EVERY MINUTE.

Earhart eventually realized that she would not be able to contact Ontario with a request for homing signals because her radio was not equipped to transmit on frequencies that Ontario could receive so she then sent the following message five days later:

6 a.m. 7-1-37 Earhart to Black:
 ASK ONTARIO BROADCAST LETTER N FOR FIVE MINUTES TEN MINUTES AFTER HOUR GMT 400 KCS WITH OWN CALL LETTERS REPEATED TWICE END EVERY MINUTE.


Brandenberg has stated that he could find no document showing that this last message was forwarded to the Ontario but, inherent in Brandenberg's statement is another statement, that he also found no document showing the opposite, that showed that the message was NOT forwarded to the Ontario. Apparently the record is silent on this point. At law there is a solution to this type of a problem called a presumption. For example, there is the presumption of "regularity" an example of which is that a letter that is placed in a mail collection box was duly delivered unless you have evidence that actually shows that it was not. There is also the presumption that people will do their duty and Black was certainly under the duty to forward that message onto the Ontario, its critical importance is clear to anybody. Absent any evidence showing that Black did NOT do his duty, this presumption is enough to prove that the message was forwarded to the Ontario.
This raises another issue, was Ontario ever notified of Earhart's takeoff so that they would know to start sending out those "N"s. The answer to this question is found in Itasca's radio logs. At 1812 Itasca time on July 1 (0542 Z July 2nd) Itasca copied a message sent from the Navy communication station on Samoa, call sign "NPU," to Ontario, call sign "NIDX," informing Ontario that Earhart was going to takeoff at 9:30, she actually took of at 10:00, see attached. From this message, Ontario knew that it should send out the "N"s every hour starting at ten minutes after each hour GMT. (Ontario was keeping time on an even one hour time zone, eleven hours ahead of GMT, so there is no chance of confusion about "TEN MINUTES AFTER HOUR" as there is concern with the Itasca 1/2 hour time zone.)

This explains why Earhart and Noonan continued on to Howland, since the reception of a good homing signal from Ontario, on which Earhart was able to obtain a null, the accuracy of which was further confirmed by their spotting Ontario only 15 minutes later, convinced them that they would be able to use the RDF to locate Howland. This provided a second and independent means of locating Howland in addition to Noonan's celestial navigation. Unfortunately, Earhart didn't understand that being able to obtain a null on a 400 kcs signal from Ontario did not prove that it would work on the 7,500 kcs signal that she had requested Itasca to transmit.

gl
« Last Edit: August 14, 2012, 04:23:05 AM by Gary LaPook »
Logged

Kent Beuchert

  • T1
  • *
  • Posts: 39
Re: Visibility of light claimed by LaPook badly mistaken
« Reply #514 on: May 24, 2014, 03:06:37 PM »

 I haven't waded yet thru all of the postings, but an early one that claimed a candle could be detected
by human eyes at a distance of 30 miles was challenged (actually, ridiculed) by Gary LaPook, who rambled on
and on using govt regulations for ship lighting and how far they would have to be seen, etc. What Gary didn't know is that scientists at Columbia University way bck in 1941 determined that a fickering candle could be seen under excellent sighting conditions as far as 30 miles away by human eyes. LaPook's big mistake was in assuming that govt requirements for ship light visibility was in any way a claim as to how far those lights could actually be seen under ideal sighting conditions - sighting conditions can vary enormously and ship's lights must assume that sighting conditions are often less than ideal.
Reference :
   http://www.livescience.com/33895-human-eye.html

 Also I found data concerning visibility of a 100 watt lightbulb under excellent viewing conditions - 118 km or
over 60 miles.  http://sbp.so/firefly
   I also found several references to instances in which relatively small freighters could easily be seen at distances of 10 miles and beyond at night, even from the deck of a ship. One such was the California during the night the Titantic sank.
« Last Edit: May 24, 2014, 04:34:53 PM by Kent Beuchert »
Logged

JNev

  • T5
  • *****
  • Posts: 778
  • It's a GOOD thing to be in the cornfield...
Re: The flight plan, magnetic course, headwinds.
« Reply #515 on: May 27, 2014, 06:53:06 AM »

I've had to learn to take the extreme arguments with a grain of salt for the reasons you cite, Kent.  There are always exceptions, and as you point out, regulations for making vessels apparent are not so minimalistic as to be the border of what the human eye is truly capable of.  They are more intended to guarantee some acceptable level of minimum performance as I see it - and not a reliable guide as to human abilities.

One fascinating consideration among those who argue here is that they don't always do so to just apply critical thought, but to apply a certain advocacy.  It's just human, I think, and perhaps more sharply applied when it is done by a trained barrister, such as my friend Gary.  Gary might differ with me on that point and I don't mean it in a personal or mean way, but the observable fact is Gary is an adherent to a different approach to the disappearance; to Gary, TIGHAR's hypothesis seems to be nemisis to what he considers truth.

I don't say this to pick on Gary.  It's common among those who prefer to view TIGHAR as errant and adhere to another line of reasoning.

And that's also not to criticize any who merely challenge the TIGHAR effort to sharpen the investigation - there are those who do so.

Thanks for sharing your findings on the visibility of ships at sea / relevant lumens detection, etc.  I've been at sea many times, and in the air at night over land and sea (although not to nearly the extent Gary has flown over open ocean) and am fairly confident that ships are quite visible for longer distances than would occur as possible to most people, especially when well adapted to night vision, etc.  The nice thing about open expanses of ocean is that where lights do occur, they tend to stick out in sharp contrast to the vast darkness around them.
- Jeff Neville

Former Member 3074R
 
Logged

JNev

  • T5
  • *****
  • Posts: 778
  • It's a GOOD thing to be in the cornfield...
Re: Visibility of light claimed by LaPook badly mistaken
« Reply #516 on: May 28, 2014, 06:17:32 AM »

I haven't waded yet thru all of the postings, but an early one that claimed a candle could be detected
by human eyes at a distance of 30 miles was challenged (actually, ridiculed) by Gary LaPook, who rambled on
and on using govt regulations for ship lighting and how far they would have to be seen, etc. What Gary didn't know is that scientists at Columbia University way bck in 1941 determined that a fickering candle could be seen under excellent sighting conditions as far as 30 miles away by human eyes. LaPook's big mistake was in assuming that govt requirements for ship light visibility was in any way a claim as to how far those lights could actually be seen under ideal sighting conditions - sighting conditions can vary enormously and ship's lights must assume that sighting conditions are often less than ideal.
Reference :
   http://www.livescience.com/33895-human-eye.html

 Also I found data concerning visibility of a 100 watt lightbulb under excellent viewing conditions - 118 km or
over 60 miles.  http://sbp.so/firefly
   I also found several references to instances in which relatively small freighters could easily be seen at distances of 10 miles and beyond at night, even from the deck of a ship. One such was the California during the night the Titantic sank.

One other thing I should have pointed out - it's good to see a new visitor here bothering to look back through old posts to get up to speed, Kent.

I gather the post you were referring to was this one.  Yes, my friend Gary can be quite an advocate for a certain point of view, and can provide arduous detail from the most arcane sources at some length, I well understand.  He also, often enough IMO, reminds the reader to be careful about applying ideal notions to theorum. 

Again, regulatory 'stuff' is an assuring box for things to be made to fit in to assure a certain level of performance under reasonably predictable conditions.  And I am reminded that the regulation for ships' lights is based on the atmospheric clarity being 13 NM - which doesn't consider the exceptional case.  Mothership Earth's ECS (Environmental Control System) brings the price of sight-limiting atmosphere - a couple of miles or so of dense air such that the range of light is much more limited, and moreso when her stew of vapor is stirred, settled and restirred at sea, etc.

The 'rule' -

Title 33: Navigation and Navigable Waters
------------------------------------------------------------------------------------------
PART 84—ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES

§ 84.15   Intensity of lights.

K is atmospheric transmissivity. For prescribed lights the value of K shall be 0.8, corresponding to a meteorological visibility of approximately 13 nautical miles.

Maritime rule...
-----------------------------------------------------------------------
If you go into that morass of detail, notice that while the given standard for visibility is 13 NM (ref: atmospheric transmissivity, value of "K" as shown under a)), the 12 candle light is only visible for 3 NM (see third line in table 84.15(B) in the rule).  Consider then, if the existing visibility is less than 13 NM the effective visual range will be accordingly further restricted even though 'visibility' exceeds the light's range (the more dense the infering atmospheric stuff the more attenuation, and therefore the less resulting effective visibility).  And, no matter the intensity of the light, it will always be limited by the maximum visibily. 

For illustration, from how far away can one really see a light house with a powerful beam on a foggy day?  I'm reminded that on the sea visibility rarely exceeds 25 NM.  The Navy Climatic Atlas suggests that in the vicinity of Howland island in July one should expect visibility of less than 25 NM 70% of the time, less than 20 NM 60%, and less than 15 NM 50% and less than 10 NM 39% of the time, etc.  It is likely that conditions would be similar near Nauru.  To Gary's credit, consider the effects of that reality on low-intensity lighting.  Not saying Earhart didn't see either of the ships - but to be sure, it isn't a shoo-in.

All of that is for illustration - and hopefully that we might appreciate that perfect conditions aren't likely to be found at the sea's surface very often.  But we're also not talking about sea-level observations where Earhart's view is concerned, of course, so not we're not having to strictly consider the low-level lateral or forward visibility case.  We may view it downward, through the soup from an airplane, so the low-level conditions that provide that expectation aren't the same - IF the intervening atmospheric interference is less vertically than would be laterally at the surface.  And again, it is worth noting for mental sobriety that sea conditions are not likely to be ideal for spotting distant low-intensity lighting. 

And again, we do also have Earhart's reports of having seen something, so apparently something was seen - what would it have been?  I tend to favor a ship (she said as much) - but I recognize the potential peril of that assumption, largely thanks to Gary.

So what could she have seen? 

The application of lumens to assure visibility may be of some interest in considiering that for an answer, that's all.  If these points are worthy, more information exists regarding the requirements for lights on aircraft, which are also very carefully spelled out (atmospheric interference exists at altitude as well).  Notice that position lights must be 40 candles, see (and if that's more regulatory drivel than one cares for, skip it - Earhart DID say she saw something):

Regs on light...

More regs on light...

Still more...

...and more...

Notably, the anti-collision light which must be 400 candles -

Anti-collision...

Fairly stiff candella requirements for a reason: intent to be seen in time to avoid collision with relatively fast moving craft aloft.  Do they tell us much about how restricted the view of a dimly-lit ship might be from aloft?  They suggest something about atmospheric impedance - but not fully enough to preclude the view a pilot might have of a ship with well-enough attuned night vision, IMO.

Of course these provisions are meant to ensure a certain level of visibility by deliberately overcoming, to some important degree, the impediments of atmospheric conditions, etc. as we've considered them.  Ultimately they too can be quite limited - but I often see airplanes many miles away in my southern, somewhat typically hazy skies...

---

The two references you provided are interesting, but they are also theoretical computations.  The first one appears to be based on extrapolation from a laboratory experiment which appears to make no allowance for clarity of the air.  It was also based on light of (blue-green) wavelength of 510 nanometers, to which the human eye is most sensitive.  These are somewhat ideal - and of course they would be for the sake of what they did.  Point being, they have limited value in the real world. 

And once more, I'm not saying Earhart didn't see the lights of either the Myrtlebank or the Ontario - but with a nod to Gary's professorial wonderment, one might wonder, did either have lights happening to be of a wavelength of 510 nanometers?  Joshing a bit - the point is conditions were not likely ideal, and I won't swat away the question 'were their lights intense enough for this to have been probable'?  I don't really know; I do know Earhart apparently saw something that may well have been at least one of the ships.  But I will throw in, again, that I appreciate Gary's insightful analysis (yes, I confess, he largely gave me the bug for digging into this kind of stuff...).

Here's a bit of info on the human eye in this regard, here,

and,

here.

It doesn't appear by what I've seen so far that anyone ever went out into the desert or to sea to fully validate the 30 mile range of a candle as theorized (or for one thing it likely would have been mentioned in the article).  Had they sent someone to the top of a mountain with a candle and to then have test subjects press a button when the guy on the mountain moves a shutter away from in front of the flame such that the correspondence of the button pushes with the timing of the flashes would tell all, we'd have more useful information, IMO.  I'd bet one could count on 30 miles of single-candle range on the moon - but with no air to attenuate the light we also lack the ability to keep a candle lit in that place...

So could Earhart have seen either of the ships, or other lights?  I still believe she could have, but I can't be certain as to from how far away, or what they were.  Having reviewed a bit more background as of this morning (you'll notice I've edited this lengthy post somewhat to add some clarity) I am reminded of some clarifying points Ric Gillespie once posted - "ship in sight ahead" was reportedly uttered by Earhart herself at 1030Z. 

It is also noted therein that Nauru had a light - a sometimes tempting alternate to 'ship' I suppose - one "New Nauru fixed light latitude 0.32 S / longitude 166.56 E five thousand candlepower 560 ft above sea level visible from ships to naked eye at 34 miles" (and note that at an altitude of 560 feet and 5,000 candlepower, it exceeds the 30 mile single candella presumption by only 4 miles...).


Out of all that stew I have to come to some level of confidence (high or low is reader's choice) based on the web of her likely proximity at the time of the report and what I believe is reasonable to assume about the ship's lights, etc.  I also have to give her raw report some credence, as other than being a complete klutz when it came to the radios, she was pretty smart and observant and an experienced aviator.  She said she saw a ship; she may well have, despite the odds, seen a ship. 

I realize that after all the detailed analysis, that is a bit mushy of me, but it's a mushy world with a very large Pacific Ocean. 

Speaking of which, I can see 'taking that' two ways (the size of the dark Pacific that night) - 'the lights coulda been anything', or 'what else could it have been'... - a point of view thing, perhaps.  Given the light attenuation possiblities we face, a good corollary might be 'she must have been very close to have seen that after all'.

Glad to see you reading old stuff and digesting and thinking - thanks for that.

Details added for clarity 5/29/2014.
- Jeff Neville

Former Member 3074R
 
« Last Edit: May 29, 2014, 08:54:59 AM by Jeffrey Neville »
Logged
Pages: 1 ... 33 34 [35]   Go Up
 

Copyright 2018 by TIGHAR, a non-profit foundation. No portion of the TIGHAR Website may be reproduced by xerographic, photographic, digital or any other means for any purpose. No portion of the TIGHAR Website may be stored in a retrieval system, copied, transmitted or transferred in any form or by any means, whether electronic, mechanical, digital, photographic, magnetic or otherwise, for any purpose without the express, written permission of TIGHAR. All rights reserved.

Contact us at: info@tighar.org • Phone: 610-467-1937 • Membership formwebmaster@tighar.org

Powered by MySQL SMF 2.0.15 | SMF © 2017, Simple Machines Powered by PHP