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Author Topic: The flight plan, magnetic course, headwinds.  (Read 470488 times)

Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #210 on: January 11, 2012, 04:20:37 AM »

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Regarding which way to offset when starting the search pattern you would normally turn in the direction to take you to an area you haven't been through yet, if that is not the situation you normally offset into the wind, in this case to the east. But for Noonan, since they knew the wind was out of the east and they expected a smoke trail that would extend off to the west, it would be less likely that they missed to the west than that they missed to the east by overshooting the LOP because they would have had to have been much shorter of the LOP to miss the smoke, so they should offset to the west when returning to commence the modified square search pattern.

I see what you are saying. It would make a lot of sense to look for the smoke rather than the Island itself in this case. My question is did they know that a smoke trail was being laid for them or was that something the Itasca did on it's own? Had they used smoke from a boiler on other occasions? One interesting note I found looking over the logs was a reporter who stated that the smoke trail stretch out for miles and was "low on the water". This is very interesting because we can guess that the range of visibility to the smoke was not improved by the altitude of the smoke.

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Yup, whether they got the last fix at 1623 Z ("partly cloudy") or as late as 1740 Z, Noonan would have planned a sufficient offset to allow for the maximum likely DR error in the leg from that fix to the interception point. That is the whole point of the landfall procedure, to cure any inaccuracy in the DR. So yes, it makes no sense that they didn't find Howland.

Reading over the Waitt Institute re-construction report regarding the 1967 Commemorative Flight.

They were approximately 10--‐12 miles [units not specified] north of Howland Island at the moment they visually acquired the island. Pelllegreno’s account of her thoughts and feelings upon arriving and not seeing Howland, then conducting a protracted search with limited fuel resources, is extremely interesting as a human factors and perational comparison to what may have occurred on AE’s mission. Pellegreno writes a compelling narrative here, one that can not help but evoke a sense of urgency, desperation, and elevated tension. Pellegreno’s flight had the advantage of better navigation equipment, a third set of human eyes, a nearby ship providing good DF bearings, and the luxury of having departed Nauru Island, with a Canton Island destination. With all of these advantages, they nearly missed visually acquiring Howland Island. This account demonstrates the great challenge attempted by Amelia and Fred, and provides a good assessment of the difficulty in visually acquiring tiny Howland Island.

So anything could be possible however AE and FN had one advantage over this flight, the smoke trail.

As a side note, I think that report also solves the question of lighting around Nauru. There is a reference to two 1,000ft cableways on the top of the island, 556 feet above sea level, to permit mining at night. There is also reference from the director of police on the island that the chief radio operator had heard AE say that she saw the lights of Nauru several times. Even though this is the case, I still disagree that the AE spotted the lights of Nauru as this was 2nd hand information gathered after the fact.

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I am also a bit troubled as to why they would have stayed on the 157/337 line an hour after having arrived at where they thought Howland was. It makes sense that they would have started a expanding square search pattern as you suggest but this would not be the case if you were flying on the line N and S on the 157/337 LOP an hour after you had arrived. Perhaps there was not plan or knowledge of how to begin the search pattern since they were lost. Perhaps they did search and going back in the line was a last ditch effort as the fuel started to run very low.

The only way I can make sense out of this statement is that they were flying a modified search pattern with longer legs parallel to the LOP and shorter legs perpendicular to it. Earhart might say that she was flying north and south "on the LOP" when on one of these long parallel legs.

Based on assumption that this was their method of search, long North South legs with short offsets, the only thing that makes sense in my mind is that they overshot Howland to the North and were making North / South passes on a 157/337 magnetic course. If as you say they would have traveled sufficiently to handle the worst case DR error, they would have seen the smoke trail if they were on the Western side of Howland. I believe that this was also the opinion of the captain of the Itasca however as far as I can surmise, he did not expect AE and FN to be searching on the Eastern side of Howland, he assumed they must have been short and missed the smoke trail to the West and North.

I also found logs (Jacobson Database) that suggest that Itasca reported 25 NM visibility range at the time. Looking over other documents, it suggests that the CG used a coding scheme that would not have allowed this to be the case so I am a bit confused as to what the actual visibility was on that day. In any case, I am sure FN came up with his own estimate as to the visibility range.
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Martin X. Moleski, SJ

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Re: The flight plan, magnetic course, headwinds.
« Reply #211 on: January 11, 2012, 06:34:35 AM »

All of my research confirms that there was no telephone service, either by undersea cable or by radiotelephone, from Lae to the outside world in 1937. Even local radio telephone service in New Guinea did not come on line until 1939.

What is the source of the image?

Purdue.

That is not the image that you used to exclude Lae as having the capability of providing a telephone patch in 1937.  I'm referring to the communications_cable_wireless.jpg from some unnamed secondary source.

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Gary LaPook

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« Last Edit: January 11, 2012, 03:47:08 PM by Gary LaPook »
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #213 on: January 12, 2012, 10:54:25 PM »



As to its meaning to the case at-hand, I think it's been noted that the Vidal sidebar was a 'third hand' discussion (if that's the root of the need to understand the state of communications between mainland U.S. and Lae in 1937, etc.).  Maybe one day Gore Vidal himself can shed more light as a living link of sorts, or maybe not.
LTM -
I wonder when Gore Vidal first started telling this story. If he told it in the '30s people would have been familiar with the state of communications of the era, including the extremely high cost of telephone calls and the sparsity of overseas phone links, so the story would not have been accepted at that time. If Vidal waited until the '70s, then the state of '30s communications would have been forgotten and he could have gotten away with telling a made up story. Also waiting until after George Putnam had died (1950) and after his father had died (1969), those who could dispute his story were gone. It is fairly common for people to try to insert themselves into famous events, it brings some sense of fame to themselves and this is a possible explanation for Gore Vidal to make up a story like this.

So, does anyone know when Gore Vidal first started telling the story about the impossible phone call from Lae to Putnam?

gl
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #214 on: January 13, 2012, 03:26:17 AM »

Quote
Regarding which way to offset when starting the search pattern you would normally turn in the direction to take you to an area you haven't been through yet, if that is not the situation you normally offset into the wind, in this case to the east. But for Noonan, since they knew the wind was out of the east and they expected a smoke trail that would extend off to the west, it would be less likely that they missed to the west than that they missed to the east by overshooting the LOP because they would have had to have been much shorter of the LOP to miss the smoke, so they should offset to the west when returning to commence the modified square search pattern.

I see what you are saying. It would make a lot of sense to look for the smoke rather than the Island itself in this case. My question is did they know that a smoke trail was being laid for them or was that something the Itasca did on it's own? Had they used smoke from a boiler on other occasions? One interesting note I found looking over the logs was a reporter who stated that the smoke trail stretch out for miles and was "low on the water". This is very interesting because we can guess that the range of visibility to the smoke was not improved by the altitude of the smoke.

Yes, Itasca sent a telegram saying they would make smoke during the day and searchlight at night.
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Yup, whether they got the last fix at 1623 Z ("partly cloudy") or as late as 1740 Z, Noonan would have planned a sufficient offset to allow for the maximum likely DR error in the leg from that fix to the interception point. That is the whole point of the landfall procedure, to cure any inaccuracy in the DR. So yes, it makes no sense that they didn't find Howland.

Reading over the Waitt Institute re-construction report regarding the 1967 Commemorative Flight.

They were approximately 10--‐12 miles [units not specified] north of Howland Island at the moment they visually acquired the island. Pelllegreno’s account of her thoughts and feelings upon arriving and not seeing Howland, then conducting a protracted search with limited fuel resources, is extremely interesting as a human factors and perational comparison to what may have occurred on AE’s mission. Pellegreno writes a compelling narrative here, one that can not help but evoke a sense of urgency, desperation, and elevated tension. Pellegreno’s flight had the advantage of better navigation equipment, a third set of human eyes, a nearby ship providing good DF bearings, and the luxury of having departed Nauru Island, with a Canton Island destination. With all of these advantages, they nearly missed visually acquiring Howland Island. This account demonstrates the great challenge attempted by Amelia and Fred, and provides a good assessment of the difficulty in visually acquiring tiny Howland Island.
Both Pellegreno's experience and the Waitt video do not match what Earhart would have seen. Pellegreno was flying above the bases of the clouds and a cloud blocked her way so she turned off to the side. Her navigator, Bill Polhemus, said after wards that if they had punched through that cloud they would have ended up right over Howland. The Waitt video was clearly above the bases of the clouds so the clouds also blocked the view of the island until quite close.

Clouds can have two effects on searching for an island. As above, if clouds are below your altitude they can block your view of the island. If you are below the clouds then they cannot block your view but they can make shadows that might be mistaken for the destination producing extra "false islands." The problem caused by this is that they pilot might dart right and left, getting off course, in an effort to evaluate these false destinations. But, if you do your navigation carefully, keeping a good DR as you go to take a closer look at the suspected island, you can then return to your course if it does prove out to be just a shadow and continue your search. Remember, the shadows do not obscure your view of the real island they only add additional targets to check out.
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So anything could be possible however AE and FN had one advantage over this flight, the smoke trail.

As a side note, I think that report also solves the question of lighting around Nauru. There is a reference to two 1,000ft cableways on the top of the island, 556 feet above sea level, to permit mining at night. There is also reference from the director of police on the island that the chief radio operator had heard AE say that she saw the lights of Nauru several times. Even though this is the case, I still disagree that the AE spotted the lights of Nauru as this was 2nd hand information gathered after the fact.

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I am also a bit troubled as to why they would have stayed on the 157/337 line an hour after having arrived at where they thought Howland was. It makes sense that they would have started a expanding square search pattern as you suggest but this would not be the case if you were flying on the line N and S on the 157/337 LOP an hour after you had arrived. Perhaps there was not plan or knowledge of how to begin the search pattern since they were lost. Perhaps they did search and going back in the line was a last ditch effort as the fuel started to run very low.

The only way I can make sense out of this statement is that they were flying a modified search pattern with longer legs parallel to the LOP and shorter legs perpendicular to it. Earhart might say that she was flying north and south "on the LOP" when on one of these long parallel legs.

Based on assumption that this was their method of search, long North South legs with short offsets, the only thing that makes sense in my mind is that they overshot Howland to the North and were making North / South passes on a 157/337 magnetic course. If as you say they would have traveled sufficiently to handle the worst case DR error, they would have seen the smoke trail if they were on the Western side of Howland. I believe that this was also the opinion of the captain of the Itasca however as far as I can surmise, he did not expect AE and FN to be searching on the Eastern side of Howland, he assumed they must have been short and missed the smoke trail to the West and North.

I also found logs (Jacobson Database) that suggest that Itasca reported 25 NM visibility range at the time. Looking over other documents, it suggests that the CG used a coding scheme that would not have allowed this to be the case so I am a bit confused as to what the actual visibility was on that day. In any case, I am sure FN came up with his own estimate as to the visibility range.
The scale maxed out at "20 NM or more" so you cannot say with certainty that it was 25 NM though it may have been. It is unlikely that it greatly exceeded 25 NM because visibility over the ocean rarely does which is why it was only necessary to have a scale that maxes out at 20 NM or more. Here is a photo of fairly common good visibility conditions over he ocean.

Based on the Navy Climatic Atlas, in the vicinity of Howland in July, you can expect visibility less than 25 NM 70% of the time; less than 20 NM 60%; less than 15 NM 50% and less than 10 NM 39% of the time. So 40% of the time the visibility will equal or exceed 20 NM. Itasca logged at least 20 NM so there is a 10 % chance that it was more than 20 NM but less than 25 NM and only a 30% chance that it exceeded 25 NM and probably not by a lot more than 25 NM. The clouds depicted in my photo are scattered, about one octa (1/8th coverage). According to the same source, the low cloud coverage in the vicinity of Howland in July is greater than one octa 85% of the time, greater than two octas 62% of the time and greater than five octas, overcast, 25% of the time. Also see my prior post here.


gl
« Last Edit: January 13, 2012, 04:00:05 AM by Gary LaPook »
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Martin X. Moleski, SJ

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Re: The flight plan, magnetic course, headwinds.
« Reply #215 on: January 13, 2012, 06:25:30 AM »

... It is fairly common for people to try to insert themselves into famous events, it brings some sense of fame to themselves and this is a possible explanation for Gore Vidal to make up a story like this.

Gene Vidal may have started the process of aggrandizing his own role in the planning.  AE helped him get the job as head of the Bureau of Air Commerce, then he helped set the wheels in motion for government support of the trans-Pacific flights.  I can see how he may have magnified any doubts he had about Fred--and any conversations he may have had with Amelia--after the tragedy unfolded.

In other words, Gore may not have been cutting the story out of whole cloth.
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Harry Howe, Jr.

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Re: The flight plan, magnetic course, headwinds.
« Reply #216 on: January 13, 2012, 10:53:13 AM »


Marty
The basis for your statement that AE helped GV get the gov't job is?

It's prolly true since they knew each other well, very well, and participated in the formation of three commercial airlines (including TWA) and, it's been alleged, were having an affair.  Gov't help for the Flight could very well have been a Quid pro Quo.
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Martin X. Moleski, SJ

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Re: The flight plan, magnetic course, headwinds.
« Reply #217 on: January 13, 2012, 11:25:15 AM »

The basis for your statement that AE helped GV get the gov't job is?

 Ric Gillespie, Finding Amelia, p. 2.
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Harry Howe, Jr.

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Re: The flight plan, magnetic course, headwinds.
« Reply #218 on: January 13, 2012, 02:09:59 PM »


This article by Judith Thurman in the New Yorker sheds some light on the relationship between Amelia and Gene Vidal and her influence with Eleanor Roosevelt in getting Gene the job in Commerce and keeping it.
http://www.newyorker.com/arts/critics/atlarge/2009/09/14/090914crat_atlarge_thurman - - Cached - Similar pagesI'd link it, but haven't figured out how to do that yet
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Harry Howe, Jr.

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Re: The flight plan, magnetic course, headwinds.
« Reply #219 on: January 13, 2012, 03:22:41 PM »


Jeff
You got that right!!
Running on the beach in my boxers and waving my briefs wildly over my head!
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #220 on: January 13, 2012, 07:05:42 PM »

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The only way I can make sense out of this statement is that they were flying a modified search pattern with longer legs parallel to the LOP and shorter legs perpendicular to it. Earhart might say that she was flying north and south "on the LOP" when on one of these long parallel legs.

Gary,

Let's say we follow this line of reasoning, that they were flying their own modified search pattern. Let's say they are at the end of the line where Howland should have been and decided to search using this method using a 157/337 magnetic heading. Do you think that they would head North or South then travel the entire possible DR error distance, use a times 2 visibility offset, then head in the opposite direction? Do you have a different suggestion as to what they might have attempted?

A critical aspect of this would be knowledge of the smoke trail. Since they knew of the smoke trail, this would be critical in their decision process.

If you did your first pass, say to the North, and did not spot the smoke trail, you have to make a decision as to whether you were short or long on the target. If you thought you were short, you would create an offset to the East. If you thought you were long, you would create an offset to the West. Is that correct?

Do we have any information to suggest which way they might have decided to search? There is the initial North / South decision to make then there is the East / West offset decision.

Perhaps they guessed that since the smoke trail was not seen, they might have thought they they were short of the target?

Thanks in advance.
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John Ousterhout

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Re: The flight plan, magnetic course, headwinds.
« Reply #221 on: January 13, 2012, 07:11:35 PM »

I'm not aware of AE or FN having any experience with sighting smoke from steam-ship boilers.  Was the approach to Howland going to be their first time to see what it looked like?
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JNev

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Re: The flight plan, magnetic course, headwinds.
« Reply #222 on: January 17, 2012, 05:13:06 PM »

Thanks, Marty - that is helpful.

The 'vacuum pumps' as a vacuum source was nagging at me -

I checked airplane and engine data sheets - vacuum pumps were installed on 'early' Wasps - a distinction is made on the TCDS E-143 about a difference in drive-types for early and later Wasps of NR16020's type - 'tongue and groove' drive (early) vs. 'spline' drive (later).

That's not absolute proof that NR16020 had vacuum pumps in 1937 - but I don't recall a single picture showing venturis on NR16020 in all the views I've seen.  If NR16020 had them they would have been prominent enough to be noticed, I think.  NR16020 had to have had a vacuum source for sure.

For those who are not familiar, a venturi works by exploiting the total energy present in the ambient, subsonic slipstream of an airplane in flight: the air mass accelerates as it becomes constrained by the narrow portion which results in a decrease in static pressure, hence 'vacuum' (a relative term; it is really a relative low-pressure area). 

Mr. Bernouli as explained in Wiki makes more sense of this than I can relate here. 

Venturis are great - to an extent: there isn't any free lunch.  They impose drag and are subject to failure in ice - and do nothing for running major instruments reliably until sufficient slipstream is present (read: airspeed; propwash alone doesn't do it).  Pumps are far more desirable for these reasons.

I managed to find some information about vacuum driven instruments and vacuum sources as well as static pressure sources for the L10A.  This is not necessarily specific to the L10E as the manual I found relates to at least one earlier, lower powered variant - the L10A is named therein - but it is likely that the same or a similar arrangement would have been used for NR16020.  It is actually quite robust and full of redundancy:

"There are four sources of vacuum supply: Two vacuum pumps, either of which may be thrown into use at any time.  Carburetor suction from left hand engine only and Venturi tube in right hand nacelle only, mounted on No. 1 pressure baffle just inside the cowl.

TURN AND BANK INDICATOR operates from either Venturi, Carburetor suction, or Vacuum Pump.  Use Venturi except in emergency.

RATE OF CLIMB INDICATOR, ALTIMETER AND SENSITIVE ALTIMETER take their static pressure from either the pitot tube or the open cockpit.  The latter source to be used on in case of failure of the former.

DIRECTIONAL GYRO AND ARTIFICIAL HORIZON operate directly from the Vacuum Pump."


The term "open cockpit" as used here for a static source clearly means "system open to cockpit ambient", as we all realize the Electra did not have an "open cockpit" per se.  Pitot tubes commonly have static ports somewhere on the sides of their outer structure - that often provides a good 'clean air' static pressure source somewhat away from the skin.

The venturi being in the nacelle is an interesting feature - and could explain why no venturis are visible on NR16020 in the pictures.  I had not even thought of that and am trying to recall if I've seen such before - don't remember it.  If the main body of the venturi was mounted behind the pressure baffle, then engine heat may have helped keep it ice free in bad conditions.

The system used a selector valve to provide the choices outlined above.  There are some good graphics with this section of the manual and if I can figure out how to post it I will, but so far having trouble saving an image from it.

There was an air-oil separator for the vacuum pumps.  Pumps in those days (and up through recent decades) were 'wet', as opposed to the modern dry carbon vane types we now have so commonly.

LTM -
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« Last Edit: January 17, 2012, 05:22:35 PM by Jeff Neville »
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #223 on: January 18, 2012, 01:20:41 AM »

I'm not aware of AE or FN having any experience with sighting smoke from steam-ship boilers.  Was the approach to Howland going to be their first time to see what it looked like?

Well, water don't burn!  If they saw the smoke they would have known that there was something at the end of the smoke trail, a ship or an island, either of which would have been better than splashing down in the ocean. And it wouldn't take them very long to follow it to the end to see what was making the smoke even if they went the wrong way at first but that is unlikely since they knew the wind was out of the east so the source of the smoke would have to be off to the east of them. They were certainly not going to fly away in an effort to save themselves from what they thought was a forest fire.

gl
« Last Edit: January 18, 2012, 01:23:02 AM by Gary LaPook »
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #224 on: January 18, 2012, 04:37:31 AM »


I do not know why I missed this but on the 'Transmissions heard from NR16020' page:

http://tighar.org/wiki/Transmissions_heard_from_NR16020

It states at 17:42GMT (The 200 miles out message) "Vessel began laying down heavy smoke to assist Miss Earhart.". Is this really the case? I was under the impression that they started the smoke much earlier?

At 19:12 GMT is the "we must be on you" message. That is a time difference of only 1.5 hours. If the wind was out of the East at 8mph (not sure if that is 100% accurate) that would suggest the smoke trail was only 12 miles long. If they searched for another hour, the trail was only 20 miles long (20:13 GMT, last message).

A reporter also stated that the smoke was laying "low on the water". While Thompson noted that the smoke stretched out 100 miles, that observation is not really valid so far as AE spotting the smoke is concerned.
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