Talk:Amelia Earhart/Archive 7

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[edit] Radio Signals

Though there were people who 'heard' what they thought were radio signals from AE after she disappeared, some were the results of hoaxes, and the rest were not particularly credible.

A ditched Electra could send no signals. Had the aircraft landed intact upon any near by island the search would have found it. Had the aircraft belly landed it would have been seen but could not have transmitted for long. The propagation characteristics of the frequencies she was using were not good for DX - long distance - work using a V-type 1/8 (or 1/16) wavelength antenna and a transmitter of only 50 watts B+ (final amplifier tube output).

The article makes it seem as if radio signals from AE were definitely heard which is simply not the case.70.248.242.6 17:21, 29 August 2007 (UTC)

Sorry, working from another computer, forgot to sign in, I am the mysterious 70.248.246.6Mark Lincoln 17:22, 29 August 2007 (UTC)

There is strong, documented evidence from 1937 that multiple post-loss signals from Earhart and Noonan were indeed heard. You may want to have a look at this exhaustive and thorough study of the post-loss radio signals published this year by the Naval Institute Press. Gwen Gale 17:26, 29 August 2007 (UTC)

The article at present does make a statement, "David Jourdain, a former Navy submarine captain and ocean engineer specializing in deep-sea recoveries, has claimed any transmissions attributed to Gardner Island were false." The Earhart biographers have also indicated that the last two confirmed radio transmissions that were made, were at Strength 5, the highest and loudest signal that the human ear can tolerate. Captain Safford, a cryptology expert who studied the Lae airfield, USG Itasca, USN Swan, USN Ontario and Nauru Island radio logs indicated that there was no evidence that any message received after 0844-46, 2 July 1937 was sent by Earhart (Safford 2003, p. 140- 145). FWIW Bzuk 18:09, 29 August 2007 (UTC).

There are published sources which do not share Captain Safford's take, although if he limited his research to those logs I can more or less see why he might have come to that conclusion. Never mind cryptologists are not radio propagation engineers. Gwen Gale 18:15, 29 August 2007 (UTC)

Safford also had access to all the radio transmissions that were sent throughout the flight and search period. Again, none of us will be able to solve the mystery of Amelia and Fred's disappearance here but the issue at hand is to make sure that the article information is properly presented and verifiable which I believe is the case. FWIW Bzuk 19:20, 29 August 2007 (UTC).

Yep, WP:V, WP:WEIGHT :) Gwen Gale 19:44, 29 August 2007 (UTC)

The R-S-T scale for signal readability defines a '5' readability as "perfectly readable" as opposed to "4" which is 'readable with practically no difficulty. Ref: American Radio Relay League, " The radio amatures's handbook," West Hartford, Connecticut, 1961, pg 580.

The information in the Itasca logs is not very suspect.

All other communications recorded after that point are suspect for several very good reasons. Earhart was only equipped to operate on two frequencies, and those two frequencies were in common aviation use. The reason they were in common aviation use for amplitude modulated voice transmissions "A3" in radio jargon, is that they were SHORT ranged. Thus aircraft would not offer great interference with each other at a long distance. Ground wave propagation at 3120 kc is pretty much a matter of line of sight given the height of the antennas. 3120 is about 95-98 meters in wavelength. The Wikipedia gives a good clue as to the characteristics of this wavelength in it's article on the 80-meter band: http://en.wikipedia.org/wiki/80_meters. Please notice the line "As the maximum usable frequency for long distance communication seldom sinks below 3.5 MHz anywhere on the planet," That is 3500 kc.

Now, bear in mind that Earhart only had a very inefficient 1/8 wave length folded V-type antenna and then consider this statement from that article: "During the daytime, a station in middle or high latitudes using 100W and a single element antenna would likely have a maximum communication range of 500–800 km, perhaps extending to 1500 km for a station using a kilowatt and antennas with some gain. These ranges are lower closer to the equator due to higher solar radiation which produces D-layer absorption."

On the more suitable 80 meter band, a 100 watt transmitter might range between 300 and 500 miles. At best with a very efficient antenna and 1,000 watts it might reach 900 miles. Now remember that radio emissions are subject to the 'square law" which is to say they weaken as the square function of the distance. Amelia Earhart had only a 50 watt transmitter, and a low, inefficient transmitter. Miracles happen, but... Mark Lincoln 22:46, 29 August 2007 (UTC)

Oops, I meant low, inefficient antenna.Mark Lincoln 22:46, 29 August 2007 (UTC)

Mark, your submission above may serve as a new addition to the Earhart article. If you wish to elaborate some of these points, provide them as cited statements within appropriate sections of the main article. The detail you are providing may even be the basis of a sub-article, say on aerial navigation or oceanic navigation by air. FWIW Bzuk 22:54, 29 August 2007 (UTC).

WP:OR. Gwen Gale 22:59, 29 August 2007 (UTC)

There is a problem with going too far into the technical aspects Bzuk. Most of the references are technical and not clear to the general user. The information tends to be presented for technical use. For example, the antenna being used on the Electra was a V-antenna, a form of bent dipole. It is very directional in two directions ahead and behind the airplane. This means two widely separated DF stations would have drastically different signal strengths (ref: ARRL "The radio amateur's handbook, 1945 edition", pg 216). Had Howland Island's HFDF been working they would have been taking a hack on an airplane coming head on, and thus could have made a good reference. But for two distant and widely separated stations to have both had good hacks on the same signal from a low power transmitter are slim.Mark Lincoln 23:17, 29 August 2007 (UTC)

You are both probably right, let's leave it as is for now, other than if any statements are to be introduced, make sure that they are adequately researched and properly cited. Thanks again, everyone, now let's look at the article to get it ready for a Good Article submission. FWIW Bzuk 23:35, 29 August 2007 (UTC). Sorry for that last aside, it made me sound like Mickey Rooney talking to Judy Garland, "Hey gang, golly gee, let's make a musical!!" (Mark will know my reference, I am not sure Gwen will [:¬) ) Bzuk 23:43, 29 August 2007 (UTC) .

I must have missed something. What is the significance of "WP:OR." I understand QRN or QRM, which are natural and man-made interference, but what is "WP:OR"? I am not arguing that the article be drastically revised or technically complicated. All I am saying is that there are VERY compelling technical reasons why any assertion that communications were heard from AE after fuel exhaustion or landing on Garner, Baker or Shangri La, had been achieved. Who else besides the Itasca monitored her final known transmissions? I feel the article should be simply modified to make the assertion of communications a distant possibility, not a certainty.Mark Lincoln 23:47, 29 August 2007 (UTC)

WP:OR refers to original research. If you stick with second-hand sources and cited statements than this doesn't apply. I think Gwen was just introducing a caution that your opinion/understanding needs other verification. FWIW Bzuk 23:52, 29 August 2007 (UTC).

It is not 'original research'. It is simply the results of an adolescent hobby. The 80 meter band is a play ground for radio amateurs and the radio equipment available on the Electra is well documented. I am not even asking that a lot of electrons be expended on the subject.

All I am trying to point out is that there is little technical reason to believe any of the communications after the last recorded by the Itasca.

Thus it is quite reasonable that the assertion plainly made in the article that such communications were from Earhart should be treated as very doubtful and speculative instead of certain.

It is not a matter of the issue of the capabilities of radio communications at the time being in question. Nor is it a matter of whether a 50 Watt transmitter could have been heard thousands of miles away. Nor is it a matter of whether the efficiency of a 1/8 wave antenna is not documented. Nor - go and read it, the article in the Wikipedia on the 80 meter band - is it a question of whether the ranges of such radio transmissions are not a matter of physics, as are the "D" layer absorption problem, the E and F layer reflection abilities on those frequencies, or the 'square law' a fact of radio transmission.

What is important to the article is that the FACTS of radio transmission were the same then as now. Just physics. There is a very, very low probability of any transmission from Earhart being received beyond a few hundred miles, much less a thousand, by anyone if she was down on an island in the central pacific The article should reflect that, and not the position that transmissions were definitely heard from her.

I brought this up on the discussion page rather than go around writing a volume of information because I am not on a soap box.

I was presenting data from a book I received as a birthday present and another that I bought used because I have a great interest in the development of radio technology. I guess if you demand it I can write a detailed piece revealing the state of radio communications in aviation at the time. But that is not necessary.

Until then just consider whether the statements that radio communications were probably heard from Earhart do not cross the line between what is a technically probable neutral point of view.

For that line not to be crossed, find some evidence that the Chapters 9 and 10 of the Radio amateur's handbook for 1945 does not give a good representation of the state of the art in 1937 concerning Wave Propagation (chapter 9) and Antenna Systems (chapter 10).

The probability that stations thousands of miles from a 50 watt transmitter connected to a 1/8 wave antenna would hear a signal are very low. That two RDF stations trying to take a hack on a highly directional V-type 1/8 wave length antenna and getting anything useful is even lower.

That everyone at Pan Am and elsewhere were willing to grasp at any straw cannot be taken as 'evidence' that Earhart was heard after the morning of 2 July any more than we can be 'certain' because folks have tried to locate those miners in Utah, that they are alive today.

The article, if it is to have a NPOV, cannot assert that communications were heard after the morning of 2 July.

The technology of the time, and the physics of today argue strongly against it.Mark Lincoln 01:17, 30 August 2007 (UTC)

Mark, I believe a case has been been built for either of the two most-widely accepted theories and since there is some controversy over the issues of fuel on board as well as post-crash messages, that is reflected in the text. Since there is no resolution to the differences that various researchers have advocated, that information is presented. Carefully writing that section is also key. FWIW Bzuk 02:10, 30 August 2007 (UTC)

It is ok Bzuk. I am not going to alter anything. That some folks wished in early July 1937 that AE might be found is true. That some were fiends of Fred is also true. That those who thought that they had heard the last of it were those near Howland hearing her last hours of communications felt that they HAD heard the last of it is also true.

If you wish the article to state that communications were heard from AE after the morning of 2 July, so be it. If you wish to pretend that Pan Am radio operators were able to make DF hacks on frequencies she could transmit with the power she had, do so.

Gwen wins I guess. The Gardner Island hypothesis - for there is no proof - is the accepted one.

That the Pacific is a large place and the Islands in the central pacific are few and far between is a fact. That radio communications are subject to the square law is also a fact. The propagation of radio signals in the equatorial regions on various frequencies are a fact.

This is not "original research."

Any argument that fundamental facts of physics and the known configuration of AE's plane are not reason to question whether there were definitely radio communications heard from her after the last heard by the Itasca - and no one else - is simply absurd.

Have a good time getting that 'Great Atta Boy" on the article. I will change nothing. It is pointless if the idea that there were communications definitely heard from Earhart for days after 2 July 1937.

I can only speak of physics and technology. I cannot argue against wishes or disprove them. Anyone who has had a class in logic knows you cannot prove a negative. Therefore I cannot PROVE that any communications from Earhart after the fuel exhaustion time of the Electra did not happen anymore than someone can prove that an airplane sitting on Baker Island could not have sent communications for days afterwards.

What I can ask is this - why did ariel searches of those Islands not detect the presence of a Lockheed L-10E sufficiently intact to send those messages which you and Gwen seem so determined to state were fact?

Have a nice one! Mark Lincoln70.248.231.174 02:32, 30 August 2007 (UTC)

Nice summation of the issue, Mark. FYI, I do not advocate the view that post-crash messages were viable or not viable, I am simply stating that the information presented on both "Crash-and-Sink" and Gardener Island disappearance theories are the most commonly accepted theories/hypothesis. Gwen had mainly written the Gardener Island Theory section, while I had written the "Crash-and-Sink" Theory. If you carefully read my submissions on this talk page, you will surmise where my personal views actually lie. Like yourself, I am more of a "Occum's Razor" proponent. As I said before, an addition to any of the theories is encouraged but careful writing, referencing research sources and proper citation is the key to making the submission work. IMHO Bzuk 02:51, 30 August 2007 (UTC).

William of Occam was a clear thinking man. What would he have said to the idea that despite the FACT that physics are physics, that AE only had a 50 watt transmitter, that on the morning of 2 July 1937 she and Fred Noonan had missed their objective, that the range of her transmissions at that time was such that no one other than the Itasca heard her last transmissions -- and that therefore the answer is that she must have been transmitting signals for days after she would have had to ditch or land and that they were heard all over the world?

Ok, I understand. Have a nice one but the AE article will be nothing more than a bleat for what amounts to the theory that not only did AE fly to Gardner Island but the USN refused to rescue her. She just MIGHT have made Gardner Island, but if she arrived in condition to transmit for days, then the USN had to have deliberately left her to die.

Did ANY pilot checking Gardner Island see an Electra standing proud on it's landing gear, able to run it's engine for days after the landing so that AE could send desperate pleas to the world? Ok, why did none of those pleas mention the USN airplanes that refused to help?

I know, you can't prove a negative.

But the fact are that no one can prove that AE landed on Gardner, that she sent messages for some time after that landing, that for some unknown reason the Electra disappeared after that, or the USN deliberately left he to die.

That is the situation with Gardner Island. Either the Electra suddenly disappeared or the Navy left her to die.

What would Willam of Occam say?

I never rewrote the radio messages twaddle. All I asked was that you and Gwen consider amending it.

That you consider such a move beyond reason is clear.

Give Gwen a hug and bye.Mark Lincoln70.248.231.174 03:22, 30 August 2007 (UTC)

Mark, that's not the issue. Rewriting the radio messages "section" is fine. You or anyone can rewrite it. All that is asked is to have reference sources cited. I had already included the statement that the majority of research predicates against any post-crash radio transmissions. If you want to elaborate or rewrite this section to emphasize it, please do so, but also ensure that the sources you use are verifiable, second-hand references. I do not have an opinion as to which disappearance theory is predominate although it is clearly stated in the article that two theories have the most support and that the majority of researchers are of the opinion that the Electra was probably lost at sea. Other research, mainly TIGHAR champions a crashed on land theory. I think your recent elaborations of the complexities of 1937-era radio transmissions and especially the peculiarities and uniqueness of the Earhart transmissions needs to be addressed. FWIW we are both arguing the same case. Bzuk 03:57, 30 August 2007 (UTC).

Bzuk, I could have pursued academic history had I wanted to. I had seen enough enough of the academic world in 4 years to know I didn't care for it. The radio signals section was clearly written by someone who is enamored with the Gardner Island hypothesis. It is also clear that any reference to the actual physics of radio communications as well as procedures and equipment will be deemed "Original Research." That is why I argued here and asked for someone else to consider mitigation what are pretty blatant claims based upon very weak evidence. I never have figured out why Earhart and Noonan didn't go out and wave when the Corsairs of the Colorado were buzzing Gardner Island. I guess they slept right through it. I also do not know why they decided to hide the Electra. I can't prove they could not have made it there, though if Earhart is to believed in her last few transmissions, she couldn't. One thing I do know is that a 50 watt 80 meter ham transmitter 25 years later, using a full wave center feed dipole at a height of 50 feet could work a distance of under 500 miles, was not a "DX" rig by any means, and the idea of the transmissions being heard in Hawaii or in Florida. Even on 40 meters it would be pretty iffy to be heard in Hawaii with that power. Certainly not with a 1/16 wave length antenna. You might be amused by the discussion of being a ham in Hawaii on this site: http://www.chem.hawaii.edu/uham/hfop.html. Notice he says nothing about 80 meters, only the higher frequencies - and remember that Earhart was up around 98 meter wave length: http://www.chem.hawaii.edu/uham/hfop.html. Pay particular attention to what he has to say about antenna systems. Also note that he is usually talking about CW, A1, transmissions which Earhart lacked the ability to do.You might also see what a complex antenna he has to use to work DX on 40 meters while on field days: http://www.chem.hawaii.edu/uham/kh6bant.html.

The radio signal section needs to take into account the improbability of signals from an airplane on the ground on Gardner Island being received at locations which claimed to have heard them, instead of emphasizing that they were heard. The issue of why AE and Noonan were not there when the Navy went looking is another matter. I repeat, I cannot "PROVE" that they didn't go to Gardner Island, but the chances are more a possibility than a probability. I just don't think that given the editorial situation that efforts at editing on the AE article are a productive use of time. There are other articles to work on.Mark Lincoln 19:23, 30 August 2007 (UTC)

(undent) If the issue here is a statement that it is very unlikely a signal could be heard on Hawaii, I do believe that is worth mentioning, as it casts the issue into doubt, which I think is very much warranted. Sadly, this is precisely the thing that is likely to be challenged! Surely it can't be that hard to find a ref for this?

Wait, that took all of about 30 seconds... from here I quote "Daytime communication range is typically limited to 400 km, primarily via ground-wave propagation. At night, signals are often propagated halfway around the world." The articles here, 160 meters and 80 meters are also useful. Nothing I read in these suggests it's impossible however, and nighttime might have been doable. Maury 21:36, 30 August 2007 (UTC)

Thank you Maury, of course the question of night time propagation depends upon skips - there are regions where no signal will be heard - and the 'square law." I guarantee you that a kilowatt will get a lot farther than 50 watts.

Lots further. Then there is another problem. DF at this time depended upon the use of "loop" antennas. See pictures of Earhart's airplane for an example. The method involved finding a 'minimum' signal. The point where the loop presented the least receiving aspect. This could give you the direction towards TWO points. One 180 degrees the opposite to the other.

I am glad to see people considering the physics of radio reception. Now we need to consider the technology of the time and the technology of the radio set up on the Electra. Recently it has been suggested that Earhart lost her reception antenna on take off from Lae. Ok, I don't know why I never read that someone found it.

Let us forget the folded dipole antenna on the bottom of the aircraft. Look at the top. There is a mast with a V-type antenna connected to the vertical stabilizers.

Let us then consider the signals which Pan Am received in Hawaii. They were 1/1. Barely heard and unable to be made sense of. Then consider that they came from either in roughly the direction of Gardner Island or perhaps Howland, OR they came from 180 degrees the opposite direction. How many radio frequency emitters in each direction?

Gwen, are you so certain that PAA received really sound signals that indicated AE was sending from where she landed on ground on Gardner Island and PAA was able to gain a totally accurate fix on them? Or could folks at PAA have tried to help by doing their best with what might have been very weak signals that they could not identify except that they MIGHT come from somewhere south of Howland?

The Garner Island hypothesis is a house of cards Gwen. I am not saying it should not be presented. It is, just within the realm of possibility. I would rather it be presented by an advocate than an opponent.

But float planes from the Colorado were sent - in response to the PAA reports - to check all of the Islands south of Howland. Those planes were flown by men who wanted very much to find AE. They went in low, so low as to be threatened by birds flushed by their appearance. They even landed when people were seen (Hull Island).

Tell me Gwen, where did AE and Noonan hide the silver and orange Electra to hide if from those who were trying to find them?

And, Gwen, why did Earhart and Noonan not try to gain the attention of those so eager to rescue them?

I can point out how Long loaded his book to promote his 'solution."

I have no "solution." It is a very big ocean. And there isn't much land to land on.

"ditch and sink' is not just a hypothesis, it is a probability. Because there is no evidence to disprove it, it is a theory. Yet it is a theory which is notmore than a possibility, it is by the simple fact that over 99% of the world in range of the Electra at then point where Earhart said 'we must be upon you' is water, and therefore it is a 'probability.' They didn't find Howland, and if Howland wasn't on the "line 157-133" then none of the other islands were either.

They were either east or right of that line. They were probably north and possibly south of Howland.

Someone who does not know where they are will be very lucky to set out in any direction to a place which they do not know where it is.

Iif you don't know where you are, you can't know where you are going.

Sic gloria transit mundi. Which is an old way of saying, "you pay your money and you take your chances - and in the long run it doesn't matter."Mark Lincoln 00:01, 31 August 2007 (UTC)

No, just look at a map Mark. Finding any beach within range isn't as difficult as finding Howland specifically. So the fact that 99.99 percent was water isn't such a big fact when you recognize that there was a pilot and a navigator controlling where the aircraft set down. Flying at 150 mph would give them a good range, which of course was part of the problem with where to begin the search.

When the Itasca said that they were close because the radio signal was strong, did that mean Earhart was one mile away or 100 miles away? How come the traidional story has never defined this distance for the reader? Matt605 16:02, 1 September 2007 (UTC)

Signal strength 5 marked the last Earhart radio transmission and is so loud that it is the loudest a human ear can tolerate. The radio transmission meant that the Electra was in close proximity. Contemporary accounts of the transmission indicated that the radio operators had to remove their headsets when the radio message came in. FWIW Bzuk 17:15, 1 September 2007 (UTC).

Matt, I have looked at the map. Samoa is 2300 miles SSW of Hawaii. I doubt if AE was 1 mile from Howland because at that range she could have seen them and they could have heard her engines. Given she was on 3105 Kcs and it was daytime, and her altitude was 1,000 feet, then it had to be ground plane for it to be '5' signal strength. Most certainly under 100 miles. Probably far less than 100 miles. (check out the concept of 'ground plane" reception at 96.6 meter wavelength). How far away the L-10E engines could have been heard would have been somewhat dependent upon winds, but I have often heard SNJs 4-5 miles, the SNB could also be heard at that range. Good guess that Noonan didn't miss by much. Matt, all of the beaches in 'range' were checked in the first week by planes from the Colorado. No one has yet explained how AE and Noonan hid the airplane. Unless, of course, Elvis took it away in his UFO.Mark Lincoln 19:12, 1 September 2007 (UTC)

The exact fuel load onboard the L-10E is given differently by different sources. We know that the fuel added at Lae was 785 US gallons. We know that the right main wing tank (97 gallons) was 'half-full" and would have been used for what was a perilous take off. The original flight plan had been made (as it should have been) with 'still air" calculations. The the morning before they took off the USN in Hawaii was predicting roughly 15 mph headwinds. After they took off they were informed that reports of winds aloft from Nauru and Howland led the USN to change the forecast to 26 mph headwinds. That means they were going to have to fly something like 450 additional miles through the air. Instead of flying 2,556 miles, they would have to fly something over 3,000 miles. We also know that early in the flight AE reported they had climbed to 10,000 feet. That meant the dragged a lot of gas way above the optimum fuel consumption altitude for that stage of the flight - and that would drastically increase fuel consumption for that part of the flight. Because there is a base fuel consumption required to keep the airplane in the air, the only way to get where you are going with a headwind without digging deep into reserves is to increase your airspeed to keep your ground speed up. This unfortunately increases your fuel consumption, but not as much as flying hours longer. The upshot of it all Matt is that Noonan appeared to be using a "sun line approach" method to locate Howland, that requires an offset in a known direction so as to 'miss' in azimuth and turn at the proper distance to fly in the direction you know the target should be. Thus the actual flying distance given head winds for AE from Lae to Howland would have been about 3,000 miles, and the still air range with 1,100 gallons about 3,375 miles. Thus had AE flown precisely to Howland instead of using a 'sun line approach" to it she MIGHT have just had fuel to fly to Gardner. Given that she was probably offset to the north - there were sound reasons why the Itasca searched northwest, then northeast and further northwest before chasing fairy tale signal reports - then it is very unlikely she could have made it to Gardner Island. As a 50 year old flying song goes "the bastard won't fly, when the tanks they run dry."Mark Lincoln 19:12, 1 September 2007 (UTC)

I don't 'know' what happened to AE and Noonan. I have a pretty good idea what the factors at work were, an understanding of the aircraft, navigational and radio technologies of the time, and abundant real data to give structure to my understanding.

From 1,000 feet with perfect visibility the horizon is something like 45 miles away. In the real world your lucky to see half that. The 'point' they were headed towards was, we now know, some five miles from where Howland Island actually is. They left flares and smoke bombs in Lae, so much of the time Noonan would have been navigating without a good drift reading. Matt, shit stacks up against you. Most airplane accidents don't have a 'single' cause, but are a compilation of things that cause people to make mistakes. How efficient are you after over 24 hours of continuous hard work? Both AE and Noonan were good at what they did for a living. What they were attempting required a RDF or lots of reserve to fly a box search to be certain of success. For reasons of their (mostly Earhart's) own, they did not have the ability to send transmissions at the wavelengths the Itasca's Low Frequency Radio Direction Finder could home on. The Itasca had deployed an experimental High Frequency Direction Finder but the batteries powering it went dead. The L-10E had a DF loop antenna that could be switched into the receiver, but a "murphy" in the design of the coupling box meant it could not be used on all the frequencies the receiver could hear. The plan for radio communications and RDF was confused, the Itasca and AE were on different time schemes, changes had been made in the equipment available and techniques to be used between when Capt. Manning briefed the Coast Guard in the Spring and when the flight was flown. They might - just might - have reached Gardner. They didn't make Howland, and checks of Baker and the Phoenix Islands - including Gardner - in the days immediately after their flight, produced NO evidence that they had landed on any of them. It is a very big ocean Matt, and those parts where they could have landed had no airplanes upon them in early July, 1937.Mark Lincoln 19:12, 1 September 2007 (UTC)

Bzuk, the fact that the radio men did not log a second number says much. The first number is "readability" and the second is "signal strength." 5/5 would be easy to read and very strong. They could barely hear her at 2:45 (Itasca time) she is readable by 3:45, by 7:45 she thinks she must be right on them, and they thing she is very close. This all indicates that the last 700 miles or so of the flight she was getting closer and that the night time propagation (lower D layer) was good, and by day time when the "D" layer would prevent skip she was close enough for ground wave reception. By 7:42 the pucker factor in the L-10Es cockpit had to be pretty high.Mark Lincoln 19:12, 1 September 2007 (UTC)