Forum artHighlights From the Forum

January 25 through 29, 1999

Subject: AE and HF/DF
Date: 1/28/99
From: Daryll Bollinger

Ric wrote:

> If experiments were being conducted in HF/DF at the time Earhart disappeared, that
> does not make her part of those experiments.

Ric I don't understand what you are saying here ?

1. Are you saying HF/DF radio equipment was considered standard aircraft radio equipment in 1937 ?


2. Are you saying AE did not have HF/DF radio equipment on board the aircraft ?

If No. 2, then there is evidence that she did by the messages sent before the take off from Lea, and her own in flight transmissions.

Itasca sent this to AE on or about 6/30/37


The only reason I can think of to transmit the letter A with call letters is for a homing device, a DF direction finder. I believe 7.5 megacycles = 7500 kcs which is HF high frequency. Put them together and you have HF/DF.

Itasca Primary Radio Log entry for 07:58 a.m. July 2, 1937



Both of these transmissions from AE seem to confirm that she did have a HF/DF radio and that she heard the Itasca on 7500 kcs but could not get a minimum.

One last question.

I thought NRUI was used to identify the Itasca. Can you explain: (2) following NRUI and the rest of the radio code that followed?



From Ric

There is no question that Earhart asked Itasca to send signals on 7500 upon which she intended to take DF bearings. What is not known is whether this was a reasonable request goven the DF equipment she had aboard. If her only receiver was the WE20B, then it was a major error for her request that frequency because, although it was within the bandwidth she could receive, it was far too high for DFing. If she had another receiver aboard the aircraft with HF homing capability, it still seems very odd that she would ask for signals on such a high frequency. Why not establish your position with a good, ol' reliable low frequency bearing before conducting tests on an experimental high frequency? Heck of a place to conduct an experiment. It is also apparent that she only tried to DF on Itasca after her attempt to get them to DF on her failed. And if she did have an HF/DF capable of homing on 7500, as you suggest, why was she unable to get a minimum?

Everything points to Earhart's request for signals on 7500 being a gross misunderstanding on her part of the limitations of her equipment.

> Can you explain: (2) following NRUI and the rest of the radio code that followed?
> NRUI2 DE NRUI P AR 0800-3

  • NRUI2 was the call sign for the HF/DF on Howland.
  • DE means "from"
  • NRUI is Itasca's call sign
  • P can mean "priority" but that doesn't make much sense in this context.
  • AR means "end of message"
  • 800-3 means that the preceding message came in between 0800 and 0803

This seems to be a message from Itasca to Howland asking if he was getting these long dashes on 3105.

Immediately after this message, (at 0804) NRUI2 replied that he was receiving no signals on 3105 and that it was "impossible to work."


Subject: On-Topic Questions: History Channel Show
Date: 1/28/99
From: Gary Moline

Just watched the History Channel AE special again and it raised a few questions in my tiny little mind.

[From Ric: I'll answer Gary's questions as we go.]

1) In her message to GP just before leaving Lae, AE said something about "personnel unfitness" and most people assumed that meant that FN was hitting the bottle again. But, didn't AE have a stomach ailment that was bothering her? Could she have been talking about herself?

[We have no evidence of any ailment or "unfitness" of either AE or Fred while they were in Lae. AE had a couple of minor bouts of stomach trouble earlier in the flight -- once due to gasoline fumes in the cabin and once due to spicy local food -- but nothing in Lae. What she meant by "personnel unfitness" is an unknown.]

2) What is your gripe with Linda Finch? When she made her flight, did she fly from Lae to Howland? What's on Howland now?

[I have no gripe with Linda Finch. I've never met the woman and she never did anything to me or to TIGHAR. As I understand it, Finch flew from Tarawa to Kanton and then backtracked to fly over Howland in a separate flight that returned to Kanton. She then flew to Hawaii via Christmas Island. She, or more accurately her crew, never flew any leg remotely approaching the lengths that Earhart and Noonan flew.]

3) The TV special showed some interior shots that I suppose were the L-10. What was the cabin layout? Could they move from the cockpit to the aft section of the cabin? Did FN make his nav shots from the side windows only?

[We don't know what the cabin layout was for the second world flight attempt but it's clear that although crawling over the tops of the fuselage fuel tanks was a bit awkward, they could move freely about entire aircraft interior. We don't have any direct evidence about where Fred took his sightings from, but according to Earhart's mechanic Bo McKneely, he took most of them form the copilot's seat where he usually rode.]

4) Is there a web site that has the radio transcripts on it?

[No. There is a CD available from TIGHAR.]

5) What was GP's response to the LTM telegram? Did he know who it was from?

[His only response was to correct his mailing address and ask that he be informed of anything further. There is no indication that he knew who it was from.]

6) Has Ty Sundstrom done any more research on the piece of wire that you all found on Niku?

[No. Ty was not able to provide any helpful documentation on the cable. Mike Everette has had much better success and is till working on it.]

7) How about the post flight radio messages that were supposedly heard days after the flight? Didn't one radio reception (Oakland?) have a bearing on the radio transmission but the others didn't? If it did have a bearing on it, does it cross Niku?

[I can't begin to address the issue of post-loss radio messages here. It's a huge, complex, and ultimately inconclusive avenue of investigation. The 8th Edition of the project book will include a section on what is known but the bottom line is that Pan Am DF facilities on Oahu, Midway and Wake (not Oakland) took bearings on suspected signals, several of which appeared to intersect near Gardner Island.]

Gary Moline

Subject: NY Times Letter
Date: 1/29/99
From: Ric Gillespie

On December 15, 1998 the New York times ran a half page article in ints Science section entitled "Long-Lost Bones Offer Clues to Earhart Enthusiasts." On January 19, 1999 the paper published a letter from author Susan Butler (East to the Dawn - the Life of Amelia Earhart, 1997) in which she says, in part:

Shortly after Amelia Earhart's plane disappeared into the blue (five days after, actually) the battleship Colorado "catapulted" from its deck to inspect Nikumaroro Island, McKean Island and Carondelet Reef. They went there specifically because Amelia's husband, George Palmer Putnam, thought that these islands were a likely place for the plane to end up. The pilots reported back that the only thing they saw were ruined guano works and the wreck of a tramp steamer.....

While as the author of East to the Dawn - the Life of Amelia Earhart which came out last year, I welcome interest in the life of this extraordinarily brave human being, I find Richard Gillespie's claims less odd than the gravity with which they are taken. I can only think that so many people are fascinated with Earhart that they will grasp at any straw to write finis to her life.

I do expect that someday the Electra will be found wherever it came to rest on the ocean floor....

Ms. Butler's letter doesn't surprise me or bother me. I mention it only as an illustration of what we've been talking about for a long time. Here is someone who certainly should be an "Earhart expert" and yet says the Navy planes flew over Nikumaroro five days after Earhart disappeared (it was seven days) and that they searched there because Putnam thought it was a likely place (Putnam had nothing to do with the decision), and that all that was seen were "ruined guano works and the wreck of a tramp steamer" (the guano works were on McKean, the Norwich City was not a tramp steamer, and the Navy pilots saw "clear signs of recent habitation" at Nikumaroro).

It is little wonder that Butler is puzzled by the gravity with which the public and the media regard TIGHAR's work. This happens time and time again. We come out with news of a new piece of evidence. The press reports on it but, always eager to provide "balance", they welcome the commentary of experts like Butler, or Tom Crouch, or Elgen Long or Rollin Reineck. These people, of course, already have all the answers and pay little or no attention to any new information. They are, however, happy to express their opinions. And so it goes.

Love to mother,

Subject: RE: Butler Letter to NYTimes
Date: 1/29/99
From: Jerry Hamilton

RE: Butler letter to Times

What I have found interesting, and disconcerting, is the amount of error in books and articles by so-called experts. Since I have started tracking Noonan, I've noted that many folks talk to three people, find a document, don't check out any of it, and call it the truth. My dad used to call that the "hit and a lick" approach. Hardly thorough. More interestingly, many have no interest in changing their inaccuracies and are also unwilling to help others further the investigation. I sent Ms. Butler a letter a year ago asking for any assistance in documenting Noonan's life. Of course, I never heard back. And I had even bought her book.

RE: Putnam and the Phoenix islands.

I don't know the degree to which he influenced the Navy search, but he certainly asked them to check the area. His telegram of July 6 (from COMSANFRANDIV. to COMHAWNSEC-ITASCA-COM14-COLORADO and COMDESRON2-COMDT USCG WASHN-COM12) reads in part:

8006 Following from Putnam quote please note all radio bearings thus far obtained on Earhart plane approximately intersect in Phoenix Island region southeast of Howland island period Further line of position given by Noonan if based on Howland which apparently reasonable assumption also passes through islands period ... Therefore suggested that planes from Colorado investigate Phoenix area as practicable unquote

Blue skies, -jerry

From Ric

I know what you mean. From the beginning of this project we have been astounded at how much of the non-controversial, oft-repeated, accepted wisdom in the Earhart case is baloney.

It's probably not fair to say that Putnam had nothing to do with the decision to search the Phoenix Group. According to the official report written by the Colorado's captain, Wilhelm Friedell, the decision to search to the southeast of Howland was made the night of July 2nd when various naval authorities met aboard the battleship in Honolulu and decided that stronger than normal winds had "probably carried the plane southeast of Howland." By midnight on July 4th Friedell knew that the reported signals from the airplane meant that it had to be on land. Putnam's request of July 6th is mentioned by Friedell and seems to have been one of many factors influencing the captain's decision to concentrate his search on the islands of the Phoenix Group, but it's clear from the report that the primary factor was the navigational logic of Earhart and Noonan having run down the line of position to find land. The 157/337 line of position points like an arrow to Gardner Island.


Subject: RE: AE and HF/DF
Date: 1/29/99
From: Mike Everette

This posting may be too long. If so, I apologize; but nevertheless, let's see if we can sort some things out.

What puzzles me, is the idea of AE asking for transmissions on HF upon which she -- aboard the aircraft -- could take a bearing. Given the state of the art at the time, it was accepted practice in HF/DF for the aircraft to transmit, and the ground station to take a bearing. The ground station, or stations in the case of a triangulated (criss-cross) bearing, would then transmit their results to the aircraft. The navigator would plot his position based upon the reciprocal of the bearing(s) the station(s) gave him.

The Western Electric 20B receiver would, indeed, tune to 7500 KHz; but my analysis of the circuit does not indicate that this receiver could be used for DF on any of the high frequency bands (above 1500 KHz). The radio had dual antenna input connections, one for the low frequency bands in the 180-1500 KHz range and the other for the high frequency bands from 1500 KHz and up.

It is conceivable that the low-frequency antenna input could have been connected to a loop antenna, or to a direction-finding adapter which itself might have the capability to switch from a loop (for DF) to a wire antenna for general LF reception. The high-frequency antenna input would normally have been tied to a wire antenna, through the T/R relay in the transmitter.

Since the Western Electric transmitter was set up for 500 KHz, 3105 KHz and 6210 KHz, and the same antenna was used for all three frequencies, we must establish some possibilities about the antenna connections to the receiver:

1. The low-and high- frequency antenna inputs to the WE 20B receiver may have been jumpered together, and then connected to the T/R relay in the transmitter, so that the same antenna -- the "dorsal Vee" -- was used for transmit and receive on all three frequencies. This eliminates any possibility of using the 20B for direction finding;

--OR --

2. The high-frequency antenna input, only, may have been tied to the "dorsal Vee" through the T/R relay, and the LF input tied directly to a second wire antenna on the belly of the aircraft. This also eliminates any direction-finding use of the 20B;

-- OR --

3. The HF antenna input was as in (2), and the low-frequency antenna input of the 20B was permanently connected to a direction-finding loop antenna (rotatable type);

-- OR --

4. The HF input was as in (2), with the LF input tied to a DF adapter unit which was then connected to a loop. If this is the case, a wire antenna on the belly would also be essential for DF purposes, to serve as a "sense" antenna which gives the DF adapter(or coupler) a reference signal to eliminate the "180-degree ambiguity" problem inherent with using a loop alone. This wire "sense" antenna is also usable for general LF reception, when the loop is out of the circuit;

-- OR --

5. There was some other, unorthodox and nonstandard type of antenna-switching arrangement incorporated aboard this aircraft which, for some bizarre reason, would allow the HIGH-frequency antenna input to be connected to the same loop used for LF direction finding.

(Possibility #5 does not make good sense, because the possibility for confusion and error on the part of nontechnical operating personnel is very great.)

Notice that none of this gives the 20B any HF direction finding capability -- except some well-meaning but marginally-technically-literate soul might have thought that, by setting up (5), he might be able to include it. From an engineering standpoint this does not make sense.

A loop antenna is not a very reliable device in an aircraft at high frequencies. The reason is, that the metal structure and surface of the aircraft creates reflections of the incoming signal -- at ANY frequency -- which can and will create confusion about the exact direction of arrival of the signal. At low frequencies this can be "compensated" for, mechanically and electrically. This compensation consists of distorting the rate of rotation of the loop in certain parts of the compass circle, so that the APPARENT direction as displayed on the bearing indicator gives a more-or-less true heading even though, for instance, there may be a 10-degree error introduced by the wings or tail assembly.

At high frequencies the compensation problem of a loop becomes much more difficult because the actual physical size of the aircraft, in the case of something like a Lockheed 10E or larger, becomes a function of the wavelength of the signal. A quarter-wavelength at 3105 KHz is about 75 feet; at 6210, about 38 feet; at 7500, about 30 feet (rough estimates; I did not take the time to compute actual lengths by formula). The wingspan, the fuselage length, the length of the Vee antenna, all are nearly "resonant lengths" or some fraction thereof at these frequencies. All will create reflections which introduce errors into a loop... MAJOR errors. Given the state of the art in 1937, it does not seem logical to believe that such problems had been solved or at least minimized to a reasonable point... after all, even the LF radio compass was in its infancy, having made the scene in 1935 or so. (Before this, "radio direction finding" in aircraft consisted of fixed loop antennas, so that keeping the aircraft pointed at the station caused a "null" in the pilot's headphones. If the place you needed to fly to was right beside the station, that was fine; but if you needed to find a field located away from the station, there wasn't any way to fly a heading away from it to reach that point, maintaining a reference to the radio station.)

It also seems logical to assume that AE must have had two receivers: one for communications (probably the 20B), and another for navigation. If you have only one receiver, and you are trying to listen for bearings on one frequency while talking to someone on another, you can't hear the answering communication.

What was the DF receiver she had? Given the information at hand, it was most likely a Bendix RA-1. This radio did not have any direction-finding capability in the HF bands.

If she was asking for signals on which to take bearings, on HIGH frequencies, one of several possibilities exists:

  1. She did not know what she was doing;
  2. She did not understand she couldn't get a bearing on these frequencies because she did not understand the limitations of her equipment;
  3. She was actually asking for a bearing FROM the Itasca (i.e., that they take a bearing on her signal, and transmit the result back to her);
  4. She was in a critical situation, and trying ANYTHING which might give her a result, even though the equipment was not designed to work in this manner;
  5. She had some other equipment aboard the plane, about which we know nothing concrete but can only wildly speculate (not even reliably "deduce") at this point.

Based upon what I know or have seen evidence of, I do not believe AE had "the same DF setup as was on Howland" aboard her aircraft. The antenna requirements alone rule that out completely and absolutely; and if the type of equipment on Howland was what I have seen evidence of, the stuff was way too user-unfriendly for operation aboard an aircraft in flight -- reliable or otherwise.

Mike E. #2194

Subject: Followup to AE and HF/DF
Date: 1/29/99
From: Mike Everette

The following is to answer DarrylB's questions in his January 26 posting, and to clarify points of my earlier message today.

Darryl asked Ric, if HF/DF radio equipment was considered standard aircraft radio equipment in 1937.

The answer to this is No. HF/DF wasn't even carried in World War II aircraft, unless of course it was for some special purpose -- if even then, for I have never located any specifics on such gear for airborne use. The standard type of airborne direction-finding navigation radio was the low- and medium-frequency radio range receiver, and the radio compass (automatic or manual), until VHF Omni Range (VOR) came into use during the late 40s or early 50s.

In fact, even the B-29 bomber force in the Pacific still relied greatly on 500 KHz as a distress frequency. HF/DF was used in the Pacific theater, but without exception, the aircraft REQUESTED bearings FROM A GROUND STATION. The aircraft did not take bearings on a signal from a fixed transmitter. (A good reference on this is the book, "How to Fly the B-29 Superfortress," subtitled "The Official Manual for the Plane that Bombed Hiroshima and Nagasaki." This is a reprint of the combat crew training manual used by the B-29 force in the Pacific -- not the pilot's manual. The book was prefaced by Jeffrey Ethell. It has a very complete and enlightening section covering the radio operator, his equipment, his duties, and much, much info on operating procedures including the operation of the Pacific DF Net.)

Darryl also asked if Ric was saying that AE did not have HF/DF equipment aboard her aircraft.

I can't answer for Ric; but I outlined in my previous message why I myself do not believe she did... at least, based upon knowledge of the state of the radio art in 1937, and the knowledge we can confirm about her aircraft and its equipment.

Darryl listed a number of excerpts from the Itasca radio log, which he believes point to her having such equipment. He said, he could not think of a reason for Itasca to transmit a single morse letter followed by call sign, unless it was for purposes of AE taking a bearing on the signal.

I disagree. A good reason for this form of transmission is to simply provide a readily recognizable, repeated signal which can easily be found by someone having to "hunt" for it -- that is, with a tunable (not fixed channel) radio receiver.

I do not agree (yet) that such a signal, plus 7500 KHz, equals HF/DF.

The only questionable point raised by Darryl's log excerpts is the one about "rec'd ur sigs but unable to get a minimum." This does not absolutely say to us that AE was trying to get a minimum ("null" or a directional indication) on Seventy Five Hundred! She might have been trying to listen on 400 KHx, for example, using her DF receiver (radio compass) for the Itasca to send her a signal to home in upon... and was unable to get a null on THAT frequency.

Yes, she may have known there was an HF/DF setup on Howland, and so asked Itasca to take a bearing on HER transmissions on 3105 or even 6210. The Itasca would have then given her their bearing on her signal. AE would fly the reciprocal of that course to reach Howland. Apparently, though, the HF/DF setup on the island had eaten its batteries by the time it was really needed, and they were unable to give her the info she needed.

Simply because the Itasca transmitted on 7500 KHz at one point does not necessarily mean that AE was trying to take a bearing upon that frequency.

Of course, there may be things we do not yet know about this whole affair. But that doesn't always mean conspiracy or government complicity.

Hope this helps.

Mike E.


Here are the Itasca log entries which seem to refer to DFing. How do you interpret what's going on?

0614 local time


(Note: Earhart is using Greenwhich time and to her the time is 17:45, so when she says she wants a bearing ON HOUR she means in 16 minutes. Itasca, using local time despite having asked and being told that Earhart would use Greenwich, thinks she doesn;t want the bearing for another three quarters of an hour.)

0645 local time


(Note: Earhart's procedure is to transmit at quarter to and quarter past the hour and listen for messages on the hour and half hour. To Earhart the time is 18:15. She wants the bearing ON the half hour in 15 minutes, not IN half hour at a time when she is scheduled to be transmitting, not listening.)

0758 local time


(Note: At this time Itasca begins sending As on 7500.)

0800 local time



Back to Highlights Archive list.

About TIGHAR Join TIGHAR TIGHAR Projects TIGHAR Publications Contract Services
The TIGHAR Store Blog TIGHAR Forum Contact TIGHAR TIGHAR Home

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:  •   Phone: 610.467.1937   •   JOIN NOW