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Author Topic: The flight plan, magnetic course, headwinds.  (Read 506492 times)

Irvine John Donald

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Re: The flight plan, magnetic course, headwinds.
« Reply #405 on: February 25, 2012, 06:43:40 AM »

Can I point out here that regardless of all the speculation in this thread about how they might have navigated to Howland the fact remains that AE made one very important radio message that tells the tale. 

AE reported "We must be on you".  Those words say to me that AE and FN felt they navigated according to whatever method FN used, by the charts he had, and with the DR and fixes taken.  They felt they had navigated to Howland.  All of the speculation in this thread is about what method and procedures they used in this process. We know that they were either "off" in their navigation and were somewhere relatively close to Howland, or that they were on Howland and could not see it.  The folks on the ground at Howland and on the Itasca never heard aircraft engines so it's not as likely they were "at" Howland.  The speculation in this forum about navigation technique is, I believe, intended to try to establish "where" they actually were when they said "We must be on you.". I believe that this forum is blessed with many individuals who have their idea on where that might be. We even have the Monti Carlo Simulation to assist from the radio transmission standpoint. However it "IS" all speculation. 

It is at the point AE says "We must be on you but cannot see you" that the mystery begins. Until that point everyone, including AE and FN, expects the Electra to land shortly at Howland.  Everything they did after leaving Lae is unknown. No records exist to say what they did.  But evidence of their radio transmissions exists which suggests they were navigating to Howland as planned. Signal strength and the words used confirm AE and FN are headed for Howland. Not off spying or headed to a different destination.

So where are they when they make the "We must be on you" radio transmission?  Probably somewhere in a circle around Howland that has a diameter of several hundred miles centred on Howland.  (I think Heath did a Google Earth drawing of that.) Isn't that as close as we can speculate when all the evidence (radio signals) and navigation speculation is taken into account? 

If that's reasonable speculation by itself then what happened next?  They have a reserve of fuel to use in finding Howland or to use in Plan B or both.  What's the next reasonable stage in their flight?

Even the splashed and sank guys (Gary et al) believe they ditched near Howland. 
Respectfully Submitted;

Irv
 
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #406 on: February 25, 2012, 08:59:02 AM »

Irvine,

Personally I am walking through the flight plans and navigation issues so that I have a good understanding the challenges they face and understanding the history of navigation in that era. It is as much as a history lesson than anything else. While this thread is indeed speculation, it is just as valid as any other speculation (like the MC simulation as you mentioned). Anything beyond what is captured in photos, paper, and even witness recollection is speculation just as is the Niku Hypothesis itself. I am not troubled by the speculation as we are not spending 100s of thousands of dollars searching for the Electra and instead we are simply posting on an Internet forum kicking around ideas, the only expense is our time. It is a hobby and I do not think we should be very serious about this hobby.

Back to the conversation, you do bring up a good point about the 19:12GMT message. They certainly felt that this was the end of the line and that they should have been in the vicinity of Howland. What I am also curious about is what they did for the next 16 minutes until the 19:28GMT "we are circling" message. What happened in those 16 minutes could perhaps have sealed their fate. About a month or two ago Gary and I walked through the scenario of what they would do. Gary felt that they would have doubled back to where they were at 19:12GMT before they began the search on the 157/337 line. So they would have only traveled an additional 8 minutes then they would have to double back for 8 more. What is interesting to consider is the possibility that perhaps they did not do this.

If you try to put yourself in their shoes, looking out the window, hoping (beyond hope in this case) that the island was just about to pop in to your vision, just another mile or two, maybe to the left or right as you busily scan the horizon for even the slightest sign of something that looks out of place, knowing full well that your life is on the line, would you have stuck with procedure and started a stop watch so that if you did not find the island you could double back? What if after 16 minutes, they just said Ok, we should have seen it and then started circling at that point until they came up with a plan? I think that it is very plausible that reality set in and they might have began to panic knowing full well that they were out of visual range and had no idea where to look, long or short, in any direction. This of course all depends on the confidence they had in their ability to get a fix and to track their speed and heading. If you had a high confidence, you would more than likely double back as Gary suggested. What if you had no confidence? Why bother back tracking say 40 miles if you did not know if you were short or long that 40 miles?

What is interesting is that if they did not double back but were accurately tracking their heading and speed, just missing Howland by say as little as 15 to 20 miles, this would have put them out of visual range when they started traveling "the line" 157/337 which must have been an advanced line of position since they were not able to determine where the line was until at least 30 minutes after sunrise as Gary had pointed out previously. If I understood Gary correctly, they would not have been on this heading (North and South) had they been able to take a new fix using the Sun as by the time they did so, they would have used a different heading an hour later. This seems to suggest that they were not able to get a new fix after their arrival probably due to the conditions while searching at 1,000ft, probably below the cloud layer (although I have not seen an analysis of the cloud height around Howland that morning and this is pure speculation).

So while Gary is probably right that doubling back after the 19:12GMT message is the right thing to do, perhaps that is not what they did. That would explain why they did not find Howland at least on their first pass "on the line" searching for Howland and perhaps subsequent passes until they either searched and wandered out of radio range or as many suggest, or flew to Niku. I have not really formed an opinion yet as to what I believe as I see a case for both the splashed and sank theories as well as the Niku theory. I do believe they had enough fuel to get to Niku but I have not yet determined in my own mind whether or not this makes sense. I would guess that FN was well aware of Niku but also the rest of the Islands in the group. For myself, the most logical thing to do in my mind would be to head toward the center of the cluster of islands that formed at least a 130 mile wide target (if not more adding in the visibility range on either side of the cluster). Like most things surrounding the disappearance not all of the actions taken by AE and FN make logical sense like making such an attempt without verifying the radio (no belly antenna implied).
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John Ousterhout

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Re: The flight plan, magnetic course, headwinds.
« Reply #407 on: February 25, 2012, 09:38:18 AM »

I'll risk some thread drift to ask a seemingly simple question - where was Fred sitting during the 19:12 and 19:28 transmissions?

Was the best place to sit to help look for Howland the copilot's seat?  It's also a decent place to get a sun shot.  OTOH, it's a bad place to handle charts and perform unplanned calculations - those are easier to do in back.  You also can't determine drift from a front seat, if that was important at the moment.
I've seen no indication that the back seat had a radio headset, so Fred couldn't help Amelia with the radio nav or com if he was in back.  That would require Amelia to concentrate on the radio instead of looking out the window, meaning Fred was in back with no view ahead, and no direct knowledge of what Amelia was hearing (or not hearing), and may have been busy with his charts and calculations.  No one was looking out a window for some periods of time, and both of them may have been quite busy with their own duties.  At 150 mph, how many seconds was the island in sight? (yeah, I know it's a rhetorical question)
Cheers,
JohnO
 
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Irvine John Donald

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Re: The flight plan, magnetic course, headwinds.
« Reply #408 on: February 25, 2012, 09:43:04 AM »

Hi Heath

Don't get me wrong on my post. I am not suggesting this navigation speculation is a waste of time. Just that it appears to me that the speculation to date suggests a proximity to Howland.  This navigation thread is very interesting and if nothing else shows that TIGHAR and slashed and sank theorists agree that AE and Fn were very close to Howland when she transmitted her "We must be on you" message. I think if you guys could pinpoint where they actually were, even to the general area such as north, south, east or west it would be great but I'm not sure that could be definitely determined. 

You're points about the 16 minutes are interesting. I thought that would be AE and FN making a preliminary search of their immediate area for Howland. Although they may not have been close enough to find or see it.

They did think they had navigated correctly by broadcasting that they must be on Howland. Otherwise wouldn't they have transmitted something else like "we think we're close" or "we had an issue and aren't sure where we are." or even "FN fell asleep and we DR'd all the way". Just something that would indicate doubt in their navigation or position.

I think that FN wouldn't aim for the cluster of islands as any rescuers wouldn't have a point of reference to work from.  Announcing they are on the line at least gives some indication of their travel plan. But as Harry has said so clearly, if AE had just worded her message ever so slightly then she could have indicated exactly what they were doing. AE's radio message is almost cryptic in that she leaves so much out.

As I have stated in the past... I think it's reasonable for them to do a search for Howland initially until they realize their predicament.  I believe FN would continue to navigate through this period.  Once reality sets in they need a plan b. Looking at he charts FN realizes the Phoenix group lies relatively close. Do fuel calculations on consumption to get here. Calculate what they have remaining and subtract the fuel necessary to get to Howland.  The difference is what they can use to search for Howland. Not long so they execute plan b. No Howland so head for phoenix group using the LOP as reference for possible search by rescuers. 

For some reason AE isn't heard of again until evening on her night frequency. That's assuming you believe in the post loss radio signals. So that's my plug for the TIGHAR hypothesis.  Not including any of the Gardner artifacts, photos, native witness accounts, or other post loss signals.

I just cannot believe anyone, with enough fuel in the plane to get to The Phoenix group, would circle looking for Howland until they ran out of gas.

My two cent's of speculation.
Respectfully Submitted;

Irv
 
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Irvine John Donald

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Re: The flight plan, magnetic course, headwinds.
« Reply #409 on: February 25, 2012, 09:48:08 AM »

I'll risk some thread drift to ask a ......   No one was looking out a window for some periods of time, and both of them may have been quite busy with their own duties. At 150 mph, how many seconds was the island in sight? (yeah, I know it's a rhetorical question)

Although no one on Howland or Itasca reports hearing an aircraft there is a possibility that AE and FN were close but just couldn't make out Howland as an island. No vegetation, elevation of 18 feet. A few huts.  Clouds, large flocks of birds.  You're point might be right John.
Respectfully Submitted;

Irv
 
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #410 on: February 25, 2012, 11:34:49 AM »

Irvine,

I am not sure where they ended up but I keep thinking that they either searched to the North on the line then headed South on the line or vice verses. Because the signal strength was a 5 it would seem that perhaps they traveled for about 30 minutes in a direction, decided that was far enough, and as Gary suggested, used some kind of offset to search in the opposite direction. It is quite possible they had enough fuel to go North and return then still had enough fuel to make it to another destination like Niku. At some point I am hoping to get a conversation going about how to model fuel consumption over on this thread. The two topics, navigation and fuel consumption would be directly linked when attempting to propose a flight reconstruction that could be taken seriously. I hope also that any discussion along those lines, including software and or formulas, are posted in an open way so that anyone can scrutinize the logic and perhaps create new models with their own ideas.
« Last Edit: February 26, 2012, 05:06:37 AM by Heath Smith »
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richie conroy

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Re: The flight plan, magnetic course, headwinds.
« Reply #411 on: February 25, 2012, 10:22:15 PM »

I'll risk some thread drift to ask a seemingly simple question - where was Fred sitting during the 19:12 and 19:28 transmissions?

Was the best place to sit to help look for Howland the copilot's seat?  It's also a decent place to get a sun shot.  OTOH, it's a bad place to handle charts and perform unplanned calculations - those are easier to do in back.  You also can't determine drift from a front seat, if that was important at the moment.
I've seen no indication that the back seat had a radio headset, so Fred couldn't help Amelia with the radio nav or com if he was in back.  That would require Amelia to concentrate on the radio instead of looking out the window, meaning Fred was in back with no view ahead, and no direct knowledge of what Amelia was hearing (or not hearing), and may have been busy with his charts and calculations.  No one was looking out a window for some periods of time, and both of them may have been quite busy with their own duties.  At 150 mph, how many seconds was the island in sight? (yeah, I know it's a rhetorical question)

the glass in the rear windows of the plane was diffrent to the cockpit one's

will find the link for u an post soom
We are an echo of the past


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richie conroy

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Re: The flight plan, magnetic course, headwinds.
« Reply #412 on: February 25, 2012, 10:26:27 PM »

here is the page from purdue


We are an echo of the past


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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #413 on: February 26, 2012, 12:57:34 AM »

I'll risk some thread drift to ask a ......   No one was looking out a window for some periods of time, and both of them may have been quite busy with their own duties. At 150 mph, how many seconds was the island in sight? (yeah, I know it's a rhetorical question)

Although no one on Howland or Itasca reports hearing an aircraft there is a possibility that AE and FN were close but just couldn't make out Howland as an island. No vegetation, elevation of 18 feet. A few huts.  Clouds, large flocks of birds.  You're point might be right John.
How far away to you think you can hear a round aircraft engine and the propeller noise? I had lunch today at Camarillo airport and I watched an AT-6 taxi out and take off. This plane has exactly the same engine as Earhart's plane. I was sitting outside and I could see the plane take off and depart to the west. It started its takeoff roll 2500 feet from where I was sitting. I never heard a thing.
gl
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #414 on: February 26, 2012, 07:16:40 AM »


From Intended Route to Howland:

Quote
There is no evidence to suggest that Earhart’s intended route from Lae to Howland Island was anything but the reciprocal of the original plan. The magnetic variation along the route varies from 6 to 9 degrees East from Lae to Howland.4 Independent verification of magnetic variations during this time period indicate no errors on the part of Clarence Williams. Earhart would begin her flight steering a 73° magnetic (80°True) course, changing over to 68° magnetic (78°True).

Not that I am trying to split hairs here but I believe the true course leaving Lae was 79° (73+6) not 80° and the TC changed over to 77° (68+9) not 78°.

There is also the statement about independent verification of the magnetic variation data used by Williams. Can anyone point me to the source material that was used to verify this data? Would this have came from the U.S. Hydrographic Office or the U.K. Hydrographic Dept that was producing the Air Almanac?

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John Ousterhout

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Re: The flight plan, magnetic course, headwinds.
« Reply #415 on: February 26, 2012, 07:56:22 AM »

An air courier service makes a daily stop at the airport where I work (Grant County, MWH), on their way from Missoula to Seattle.  They fly an old Beechcraft B18, which has 2 radial engines (I'm not sure which ones this particular aircraft have - likely P&W R-985's which are smaller and likely less noisey than Amelia's engines).  On a still day I can hear them on final approach at a distance of about less than 10 miles.  If there is any wind noise at all, they're virtually silent on approach.
On take off they're a bit louder, initially.  By the time they reach 10 miles, heading away from me, they're still visible but silent, unless the wind is blowing straight from their position towards me.  In that case, they can still be heard for another few miles.
I would conclude that Amelia's plane would have been impossible to hear before it was seen, if there was any wind (there was), or other ambient noise.  The one exception might be sound carried by the wind blowing in the right direction.
I suspect that watchers on Howland were expecting the aircraft to approach from the west, and would have been concentrating their attention in that direction, more than the rest of the compass.  Had the aircraft flown within a distance of 10 miles upwind, someone might have heard them.  Had it flown within 10 miles in any other direction, it seems unlikely to have been heard, based on what I've experienced in admittedly very different conditions, and with a different aircraft.
Cheers,
JohnO
 
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Irvine John Donald

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Re: The flight plan, magnetic course, headwinds.
« Reply #416 on: February 26, 2012, 09:02:59 AM »

So here are Gary and John telling me that Gary can't hear airplanes but John can if the weather is right.  Two different opinions from two people.  So who to believe?

Of course there are factors that affect what you can hear.  Gary, was your lunch inside a restaurant or outside?  What way was the wind blowing?  How close was the runway? 

Okay now tell me what conditions would have affected the ability of the watchers at Howland?  Engine and machinery noises on Itasca, wind on both Itasca and the island, surf noise, large flocks of birds, hangovers from the night before, plain old poor hearing, building obstructions.  The fact remains that no one heard the engines and no one saw them. Yet the watchers were concentrating on spotting them.  I bet binoculars were in use too.

To answer your question Gary, I think the distance you could hear an engine is dependent on the conditions.  In the case of Howland I ONLY know that the watchers didn't see or hear them. Does that mean they weren't in visual or audio range?  No.  It means of the many watchers, and listeners, not one of them spotted the plane. Isn't that more the point Gary than arguing how far away you can hear an aircraft?
Respectfully Submitted;

Irv
 
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #417 on: February 26, 2012, 10:23:46 AM »

Here is another totally fictitious experiment that compares the Williams strip chart GC flight plan with a rhumb line that has a true course of 78° (78.27° rounded down to 78°). The hypothetical rhumb line would use the same intervals as the strip chart (for comparison purposes only). Following the hypothetical rhumb line flight plan would end up about 15SM North of Howland and just 4-5SM South of where the Williams flight plan would terminate.

What is interesting (to me anyway) is the at about the mid-point in the plan, the rhumb line is further North than the Williams GC flight path by about 7SM. It is about 20SM North of the actual GC path in Google Earth. I am not suggesting that FN used this but I just wanted to see what would happen if FN did use the same values for magnetic variation as Williams did. It is also interesting that both the Williams flight plan and this hypothetical rhumb line flight plan would be much closer to the estimated position of the Myrtle Bank.

On the GE screen captures, the red line would be the hypothetical rhumb line, the green line would be the execution of the Williams strip chart flight plan.

The spreadsheet is comparing the magnetic course of the rhumb line versus the magnetic course of the Williams chart. It does not serve any real purpose other than to show the subtle differences at the beginning and end of both flight plans.

Did I use the term 'hypothetical' enough or do I need a full hypothetical disclaimer? ;)

Update - After thinking on it a bit, does it really matter if they flew a GC or rhumb line flight plan? The celestial navigation accuracy is limited to about 15SM, so does it really matter? Perhaps this is splitting hairs? The only real difference is the number of computations to get you back to the flight line if and when errors are detected. Formulas for both exist and were probably available to FN as well.
« Last Edit: February 26, 2012, 11:05:57 AM by Heath Smith »
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John Ousterhout

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Re: The flight plan, magnetic course, headwinds.
« Reply #418 on: February 26, 2012, 10:27:01 AM »

Irv,
The lesson I take from what I've observed, and what Gary mentioned, is that these example radial aircraft engines become very hard to hear at distances past 10 miles even in the best conditions.  This implies that Amelia's Lockheed would not have been heard unless it was within roughly 10 miles of Howland.  At a stretch, we might extend that listening range to 15 miles, and might feel pretty confident that the aircraft never got that close to the island, depending on what other assumptions are made (clouds, wind, noise, etc).  That's not too far to spot the aircraft visually, especially if there were lots of eyes and binoculars in use.
This convinces me that the Lockheed never approached as close as 10 miles, and was unlikely to have escaped notice at a range of 15 miles.  I would feel confident drawing a 15-mile radius "exclusion" circle around Howland.
Cheers,
JohnO
 
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #419 on: February 26, 2012, 11:07:28 AM »



There is also the statement about independent verification of the magnetic variation data used by Williams. Can anyone point me to the source material that was used to verify this data? Would this have came from the U.S. Hydrographic Office or the U.K. Hydrographic Dept that was producing the Air Almanac?
Magnetic variation information is not found in the Nautical Almanac nor in the Air Almanac as these books provide information about the positions of celestial bodies. Also, the Air Almanac was not published until several years after the Earhart flight.
Variation information is taken off of charts so must be visually interpolated by the navigator. Here is an example. Look near the left edge of this chart and you will see a dashed blue line going past Nukumanu, this in an isogonic line and it is labled "8 E" which was the variation in that area.(Ignore the dashed green lines, they are for grid variation which is something different used, mainly, for polar navigation.) Today you can get variation information on the internet but Noonan's iPhone batteries had died.

gl
« Last Edit: February 26, 2012, 11:12:58 AM by Gary LaPook »
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