“Amelia Didn’t Know Radio” — Almon Gray

Once again I’m privileged to offer yet another erudite presentation on radio and Amelia Earhart by the late Almon A. Gray, this one titled “Amelia Didn’t Know Radio.” This article initially appeared in the November 1993 edition of U.S. Naval Institute History magazine before Bill Prymak presented it in the December 1993 issue of his Amelia Earhart Society Newsletters.

After graduating from the George Stevens Academy  in 1928 and the Massachusetts Radio Telegraph School in 1930, Gray enlisted in the Navy, where he was a radioman and gunner aboard cruiser-based aircraft, and he also learned to fly.

Following his Navy enlistment he joined Pan American Airways, and in 1935 helped build the bases to support the first trans-Pacific air service, and was first officer-in-charge of the PAA radio station on Wake Island.  After the San Francisco-Hong Kong air route was opened in late 1935, he was a radio officer in the China Clipper and her sister flying boats.  Later he was assistant superintendent of communications for PAA’s Pacific Division.  Gray, who flew with Fred Noonan, was a Navy Reserve captain and a major figure in the development of the Marshall Islands landing scenario.  He died at 84 on Sept. 26, 1994 at Blue Hill, Maine

This is the first of a three-part presentation.  Boldface emphasis mine throughout.

“Amelia Didn’t Know Radio”
by Captain Almon A. Gray, U.S. Naval Reserve (Ret.)

Almost certainly, Amelia Earhart could not get a bearing on the radio beacon on the U.S. Coast Guard Cutter Itasca (WPG-321), lying off the beach at Howland Island, rose the frequency that she had designated –7.50 Mcs* — was so high that her direction finder (DF) was inherently incapable of taking bearings on it.

(* Since 1937 the unit of measurement for radio frequencies has been changed from “cycles” to Hertz (Hz), consequently Megacycles (MCs) and MegaHertz (MHz) will be used interchangeably , as will Kilocycles and Kilohertz (kHz).)

That Earhart and Fred Noonan failed to reach Howland Island on their 1937 around-the-world flight because of radio problems has been studied before — but little has been written about the specifics. 

Capt. Almon Gray, USNR (Ret.) wrote extensively on Amelia Earhart’s radio problems during her last flight.  Gray, a Navy Reserve captain and Pan American Airways China Clipper flight officer, flew with Fred Noonan in the 1930s and was an important figure in the development of the Marshall Islands landing scenario. 

A failure in the plane’s antenna system, which made it impossible to receive signals on the fixed antenna, also was a factor.  Had she or Noonan known enough about the system to work around the failure, they could have established voice communications with the Itasca, where someone surely would have suggested they try taking bearings on the vessel’s 500-kilocycle beacon.  It could have made all the difference.

BACKGROUND: In early 1937, several weeks before departing Oakland, California, for Honolulu — the first leg of an intended west-about flight around the world — Earhart met at Alameda, California with George Angus, the Superintendent of Communications for the Pacific Division of Pan American Airways (PAA).  Angus directed the radio communication and DF [direction finding] networks that supported the PAA clippers on their Pacific crossings, and she was looking for help to augment Noonan’s celestial navigation.

The airline then had specially designed versions of the Adcock radio DF system in service at Alameda, Mokapu Point on Oahu in the Territory of Hawaii, Midway Island, Wake Island, Guam, and Manila in the Philippines.  They could take bearings on frequencies much higher than could conventional loop-type direction finders — like Earhart’s — and were effective over much greater distances.  These high frequency DFs were the only ones of their type in the United States and its territories.   Angus agreed to help and went to work on the details. 

This was complicated inasmuch as PAA could receive but not transmit on either of Earhart’s communications frequencies — 3105 or 6210 kHz — and could not transmit voice on any frequency.  Earhart and Angus decided that the aircraft would request a bearing by voice on the frequency in use — usually 3105 kHz at night and 6210 kHz during the day — and follow the request with a series of long dashes lasting in the aggregate a couple of minutes. 

The PAA DF station would rake a bearing on the transmission and transmit it to the plane on another previously agreed upon PAA frequency, using continuous wave (CW) telegraphy sent at such a slow speed that the individual dots and dashes could be copied on paper and later translated into numbers.

This arrangement was tested on the flight from Oakland to Honolulu; PAA took the bearings on 3105 KHz and transmitted the bearings in Morse code on 2986 KHz. The flight was handled much the same as a routine Clipper flight.  Captain Harry Manning, former captain of the SS Roosevelt,the ship that brought her home from Europe after her 1928 trans-Atlantic flight — and a long-time friend, was an experienced radio operator and handled the Electra’s radio and DF gear while regular PAA professional radio operators manned the ground stations.  Radio bearings furnished the plane at frequent intervals, first from Alameda and later from Mokapu Point, checked well with the positions Noonan determined by celestial navigation.  Nearing Oahu, Manning set up the plane’s DF to home on the 290 kHz marine radio beacon at Makapu Point, near Diamond Head, and Earhart homed in on it to a successful landfall.

While attempting takeoff for Howland-Island from Luke Field, near Honolulu, on March 20, 1937, Earhart ground-looped the Electra, damaging it to the extent that it was shipped back to the Lockheed plant in California for repairs. The radio gear sustained no major damage, but the Western Electric Model 20B radio receiver and its remote-control apparatus were replaced by a Bendix aircraft radio receiver and accessories.  The stub mast supporting the V-shaped fixed antenna also was moved a bit forward, and the antenna feed line was rerouted. The late Joseph Gurr, then a moonlighting United Airlines technician, did the work.

Amelia Earhart’s seriously damaged Electra 10E after her Luke Field, Hawaii “ground loop” on March 20, 1937.  Amelia and Fred Noonan can be seen standing next to the pilot’s side of plane. The Electra was sent back to the Lockheed plant in Burbank for months of costly repairs.  The radio gear sustained no major damage, but the Western Electric Model 20B radio receiver and its remote-control apparatus were replaced by a Bendix aircraft radio receiver and accessories.

THE NEW RECEIVER: The receiver installed at Lockheed was an experimental model incorporating the latest improvements.  Only three experimental units were built, although Bendix later marketed an almost identical design as the Type RA-1 Aircraft Radio Receiver.

The experimental model was a continuous turning superheterodyne that covered the spectrum from 150 to 10,000 kcs in five bands.  It could receive voice, CW, or modulated CW (MCW) signals and could be controlled remotely from the cockpit.  A switch permitted the operator to connect the receiver to either the conventional wire antenna or the loop antenna.  When the loop was used, the combination became an effective radio DF system capable of accurate bearings on frequencies between 150 and approximately 1800 kcs.  Signals on frequencies higher than 1800 kcs could be heard, but very seldom could accurate bearings be obtained.  Earhart was apparently unaware of this.  The receiver was powered by a dynamotor operated by storage batteries charged by the main engines.

THE RADIO SYSTEM: When the plane left the Lockheed plant, the radio system consisted of the following elements:

– The experimental Bendix aircraft radio receiver.

Western Electric Model 13-C 50-watt aircraft transmitter with three crystal-controlled channels: 500, 3105, and 6210 kHz — capable of voice or CW transmissions.  It was mounted in the cabin, but there were remote controls in the cockpit.

A prototype of a Bendix Type MN-20 rotatable shielded loop antenna.  It was mounted on the fuselage above the cockpit; the knob that rotated it was on the cockpit overhead between the pilots.  It was used primarily for taking radio bearings but was useful as a receiving antenna in static caused by heavy precipitation.

Fittings at each side of the cockpit for connecting a microphone, headphones, and telegraph key.

A telegraph key and a jack for connecting headphones at the navigator’s table.

A 250-foot flexible-wire trailing antenna on an electrically operated, remote-controlled reel at the rear of the plane.  The wire exited the lower fuselage through an insulated bushing and had a lead weight, or “fish,” at the end to keep it from whipping when deployed.  A variable loading coil used in conjunction with this antenna permitted its use on 500 kHz., and the antenna was long enough to give excellent radiation efficiency on all three transmitting frequencies.

– A fixed, Vee-configured wire antenna with its apex at a stub mast mounted on the top of the fuselage, over the center section of the wing, and its two legs extending back to the two vertical tail fins.  The antenna was so short that its radiation efficiency was extremely low; it was adequate for local communications around an airport when it was not feasible to have the trailing antenna deployed, but not for the long-distance communication Earhart required for her transoceanic flight.

The Bendix RA-1B, used in Amelia Earhart’s Electra during her final flight without apparent success, was a brand new product and was reputed to be pushing the state of the art in aircraft receiver design.

Either wire antenna could be selected from the cockpit.  The one selected both transmitted and received by means of a send-receive relay that switched the antenna from the receiver to the transmitter when the microphone button was depressed, and switched it back to the receiver when the button was released.

MISTAKES AT MIAMI: After deciding to change her route to east-about, in late May 1937 Earhart flew the plane to Miami, where she had the trailing antenna and associated gear removed completely.  John Ray, an Eastern Airlines technician who had his own radio shop as a sideline, did the work.  Once again, Amelia obviously did not comprehend the devastating impact this would have on her ability to communicate and to use radio navigation.  With only the very short fixed antenna remaining, virtually no energy could be radiated on 500 KHz.  This not only foreclosed any possibility of contacting ships and marine shore stations but precluded ships — most important, the Itasca — and marine shore-based DF stations from taking radio bearings on the plane, inasmuch as 500 kHz was the only one of her frequencies that fell within the range of the marine direction findersAny radio aid in locating Howland Island would have to be in the form of radio bearings taken by the plane on radio signals from the Itasca.  Earhart had cut her options severely.

The shortness of the remaining antenna also drastically reduced the power radiated on the two high frequencies.  Paul Rafford Jr., a NASA expert in this field involved in forecasting long-range communication requirements to support astronaut recoveries, estimated that the radiated power on 3105 KHz. was about one-half watt. This obviously was a tremendous handicap in the high static level of the tropics.

The fixed antenna also may have been at least partly responsible for the distortion in Earhart’s transmitted signals reported by the operators at Lae, New Guinea, and Howland as affecting the intelligibility of her voice transmissions.  A mismatch between the antenna and the final amplifier of a WE-13C transmitter could cause the transmitter to over-modulate and thus introduce distortion.

After a few days in the Pan American Airways shops during which all systems, including the antennas, were tuned and peaked, the plane departed Miami on June 1, 1937 to resume the flight around the world.

Despite these shortcomings, Earhart got as far as the Dutch East Indies without major incident. There, however, because of her unfamiliarity with radio matters, she unwittingly made the mistake that ultimately led to her failure to reach Howland Island.

THE FAULTY PLAN: The legs from New Guinea to Howland Island and from Howland to Hawaii were the most difficult navigational portions of the flight, and three small vessels were stationed along the way to assist.  Each planned to use the ship’s transmitter as a radio beacon for Earhart and Noonan to supplement Noonan’s celestial navigation.

The USS Ontario (AT-13) was on station midway between Lae and Howland.

The USS Swan (AVP-34) was positioned midway between Howland and Hawaii.

The USCGC Itasca was at Howland.  Her beacon was particularly important; should Noonan’s celestial navigation not put them within visual range of the small, low-lying island, homing in on the Itasca’s signal would be their only chance.

By June 23 these vessels were on or approaching their respective stations but had not been issued their radio beacon frequency or procedures.  That day, in a message addressed to Earhart at Darwin or Bandoeng.  Richard Black — Earhart’s representative on board the Itasca — advised her of the radio frequencies available on the three ships and asked her to designate the frequency she wished each ship to use when transmitting beacon signals.  This message caught up with Earhart at Bandoeng, Java.

(End of Part I.)


16 responses

  1. I get lost in all the technical details, but as he states, radio ignorance certainly played a major part in their plight, but all this wold ne a moot point if, as some believe, they never intended to communicate with the Itasca, and all this was a plan to ditch in the Marshalls or Phoenix Islands and be rescued so the US Navy could find out what was going in the Pacific. If that was the case, did they honestly believe the Japanese wold allow them to go poking around their fortifications? So many facets to this case!


  2. As always great information about Amelia and her issues. At the time I should imagine that her equipment was state of the art.


  3. First, I agree with Dave Kapsiak.
    When I read this blog today, what stood out to me was that Pan Am had been flying planes across the Pacific since 1935 (with Fred Noonan as navigator) with NO planes being lost. So, in 1937, this was not rocket science. I read that Fred could navigate reliably to within 10 miles of his target, but relied on signals from the Adcock DF “array” to finally find whatever island. He did NOT try to sight it visually probably because that was too risky a proposition.
    While I was searching around the internet, I found this: https://www.usni.org/magazines/naval-history-magazine/2000/august/earhart-tragedy-old-mystery-new-hypothesis

    This material may have been thoroughly covered by TAL or this blog already, if it was, just disregard it.
    Something else I learned from this link: The attitude of the plane, having landed in deep water would be a 54 degree nose down angle just as Prymak said. What turned on the light bulb in my head was the calculation used “The Center of Buoyancy” (not center of gravity) just read this article. It is debatable whether her plane could transmit when she was floating in the water “on the level” but clearly her plane could not do this. Whether it would then float indefinitely is also debatable, depending on the configuration of her fuel tanks, which I have never seen in detail. I just don’t know if they would slowly leak, or not at all.

    As Almon demonstrates, she could not get a fix on Howland and Howland could not get a fix on her with the configuration of her radio equipment. My take is that the removal of her trailing antenna was a much more serious lapse intentional or not than it is usually regarded.

    So then the question arises, was she, George and Fred and maybe Mantz and Manning all so dumb that they couldn’t foresee that their radio setup wasn’t going to work? Especially when Fred was familiar with what DID work? Was the flight’s failure the result of Amelia being dangerously ditzy and dense? IOW, is Amelia the culprit? In many writings about the flight Amelia is made to possibly look like a fool and her mishap was her own darn fault.

    I am now apprehensive that this blog won’t let me write too long a post, so I’m going to close here and write my conclusion in next entry.


  4. What I concluded today was that Amelia and George and probably Fred DID know that they weren’t going to make Howland and never intended to. When reading the Brad Washburn biography I read that on his visit to the Putnams he strongly suggested that Amelia have a strong transmitter built on Howland so that she could easily pick up the signal on her loop antenna. George brushed that off, saying “It would take too long to do that and we want the book to come out before Christmas.” Kind of a silly answer when her life was at stake.

    Brad was an accomplished Alaskan bush pilot (and mountaineer.) So I would conclude that yes, Amelia knew she wasn’t going to Howland at all and needed no fancy (or workable) radio DFs. She also needed no cameras and no souped-up engines. My guess is that the AM radio station on Jaluit was just what she needed if she was flying to the Marshalls. As we discussed here, a spy flight was not what this was about. As Mr. Trail said, there were much more professional ways of intelligence gathering about the Marshalls if that was what was intended. I say nothing of the sort was. If she flew to Mili Atoll, and here I will stipulate she did that, it was intentional IMO. No need to construct tortured scenarios of how she got so far off course. She wasn’t off course. Some might say this was her mission (Mili) as requested by FDR (probably not directly, so that he and Morganthau would have plausible deniability.) IOW, “We never told her to do that!” Some might say “Oh, FDR would not ask her that.”

    After all my mental gyrations, I agree Amelia never intended to land on Howland. She did intend to land in Japanese territory, I believe. She did not intend to “crash and sink.”She also did not and would not send any distress calls, because no one was supposed to know where she was. She knew where she was, though. Amelia could have easily relied on Pan Am to conduct her safely across the Pacific, even to Howland, but she refused because she wasn’t headed there. What she was supposed to accomplish by deliberately flying to the Marshalls and landing there we don’t know. It’s in the “secret files” located under the heading “This will stagger your imagination” not sure of the page number.



  5. I used to hate dynamotors or vibrators that equipment used in those days to get the higher voltages needed to operate vacuum tubes. Solid state equipment operates at relatively lower dc voltages, so it’s more reliable.


  6. I have the utmost respect for Almon Gray’s fine analysis, however his thinking the Bendix RA 1 receiver was installed after the Luke Field crack-up is incorrect. The opposite occurred. The Bendix Receiver was likely removed around March 1, 1937.

    Les Kinney


  7. William H. Trail | Reply

    Greetings to All:

    I must confess that until yesterday morning I had not read Almon A. Gray’s “Amelia Didn’t Know Radio” article in either the November 1993 U.S. Naval Institute History magazine, or it’s reprint in the December 1993 AES Newsletter. No excuse. And as we’d say at Ft. Bragg, “That’s a lick on me.”

    Now having read the article, I learned that the critical 250ft trailing wire antenna could be deployed and recovered via an electrically operated, remote-controlled reel. It was as easy as the push of a button, or the flip of a switch. The actuating mechanism is not specified. We know from Paul Rafford’s book, “Amelia Earhart’s Radio” (2006) The Paragon Agency, Publishers, 1st Ed., page 39, that “… it’s weight would have amounted to less than two gallons of gasoline…” Grey further offers that, “…deploying and retrieving it would be no great chore.”

    In my prior ignorance, I had believed the trailing wire antenna to be a manually operated, hand-cranked affair and that what amounted to, in Grey’s opinion,”no great chore” was a judgement call on the part of the person who had to do the deploying and recovering. What is a pain-in-the-tookus to one person may be no big deal to another. And that brings us to the alleged excuse that AE left the trailing wire antenna behind in Miami, “…to save weight and the bother of having to reel it out and in while in flight.” Given what’s now known about the weight and the true ease of the antenna’s deployment and recovery, to say nothing of it’s critical importance to the the safety and success of the fliers and flight, that argument does not hold water. 

    Let’s put this into perspective:

    Two gallons of Avgas weighs 12.0 pounds. 

    Fuel Consumption — 87 Octane (data taken from “Earhart What Really Happened at Howland” by G.C. Carrington (1977) BRITNAV, page 190)

    I used the converter below to do the calculations.


    1900 rpm @ 29″ Hg = 51.5 gal/hr or 0.85833 gal/min
    1800 rpm @ 28″ Hg = 52.4 gal/hr or 0.87333 gal/min
    1800 rpm @ 26″ Hg = 43.0 gal/hr or 0.7167 gal/min
    1700 rpm @ 26″ Hg = 36.0 gal/hr or 0.6 gal/min
    1550 rpm @ 24″ Hg = 38.6 gal/hr or 0.64333 gal/min

    What the numbers tell me is simply that the time in the air 2 gallons of 87 Octane Aviation Gasoline provided was negligible when talking about a flight of many hours duration over the vastness of the Pacific Ocean. It isn’t going to get you far. At the most optimum power setting it’s only about several minutes of flight time at most. 

    To discard such a vital piece of gear as the trailing wire antenna just to save the weight of less than two gallons of Avgas was the height of folly. And that’s the point. Neither Amelia Earhart nor Fred Noonan were stupid, inept, foolish, insane, or suicidal. So, why was the trailing wire antenna really removed and left behind in Miami? It wasn’t about weight, bother, or fuel.

    All best,



    1. OK OK OK AE crashed and died in Saipan,,WHY WAS SHE IN THE PACIFIC WAS ARENA IN THE FIRST PLACE? She was spying for the US, whatever spy gear she has was ditched at sea, a new direction for TIGHAR perhaps Ric could make a second career seeing how his first fake one was disclosed


    2. Leslie Male (M) Kinney | Reply

      William, what are your source(s) that the Electra’s trailing wire could be extended and retracted electronically? I never heard this before.

      Les Kinney


      1. William H. Trail


        My source is Almon Gray’s “Amelia Didn’t Know Radio” article appearing in the November 1993 U. S. Naval Institute History magazine, and reprinted in the December 1993 AES Newsletter. Scroll down to “The Radio System.” It’s there in the 6th sub-paragraph under that. I’d never read of it before either.

        All best,



      2. I’m almost certain the trailing wire which was remived following the Luke Field crack up along with the Bendix receiver was never reinstalled . Gray lists no sources for this and I’d rather believe Gurr who was there.

        Les Kinney.


      3. Les,

        Thanks. Whether or not the trailing wire was reinstalled after the Luke Field crackup does not in itself tell us whether it could have been extended and retracted electronically, or am I missing something? Goerner’s interviews with radio expert Joseph Gurr will be featured in future posts.



      4. It does appear that electronic trailing wire antennas were in use in the 1930’s. The following is the opening statement in U.S. Patent 2188062 issued in 1940 (the original application was in Germany in March 1937):

        “The use of the so-called trailing wire antenna is known in aviation. In order that the antenna may be always kept in a taut or tensioned state, there is attached to the end thereof either a wind bag or a weight known as a fish. It may happen that the antenna wire or strand which is paid out by the drive motor through an antenna winch gets into the drive mechanism of the motor, and this is liable to cause mechanical destruction or damage. In other words, the working safety of the trailing antennae used in the past is comparatively low”.

        The drive motor has a worm gear at the end of it which is engaged to the side of the reel. The invention included a spring loaded switch which sensed the tension of the cable; if the tension went slack the switch shut off the motor to prevent any damage to the drive mechanism.


      5. A minor technical point: An electrically powered antenna reel would be considered an electro-mechanical device, not electronic. The receiver and transmitter are examples of electronic devices.


  8. Greetings:

    That’s what I was talking about in my last post. Amelia and Fred had to know they were woefully underprepared for their flight to Howland unless somehow the story that we read about their DF deficiencies were all cooked up by the Navy. What would be the purpose of that? To puzzle armchair sleuths 85 years later? There’s more clues in this story that lead nowhere than the Oak Island Treasure hunt.

    What I thought of yesterday was that their message picked up by Nauru, “Land in Sight Ahead” could possibly have been them sighting Mili Atoll. Then it follows that their last messages that sounded like they were near Howland could have been all recordings, since she never responded directly to what the Itasca was saying to her. Did they fly off unprepared so that the Japanese would believe they were genuinely lost? Somebody or some agency in the AE story has gone to great lengths to keep this issue as mysterious as possible. But we all knew that already.



  9. I happened on this Youtube video last night. I think it has lots of useful information.

    One point this video makes is that Manning was supposed to be radio operator on her Lae flight. They say when she lost Manning she was screwed. Maybe Manning really did think she was too dangerous to ride with. Further, in the comments, especially one from a guy whose father was a pilot, the father thought she was no way qualified as a pilot to do this flight (on her own.) To add to this lack of preparation, how could she possibly have gone on to find Barre Island when she was apparently already lost? As I have previously remarked, I don’t think she would have headed for Mili where there was no airfield and landing in the sea would have been just too risky to attempt.
    There is a story about Noonan miscalculating on a Pan Am flight, apparently he was not infallible. There is the specuation that she lost the underneath fuselage anteena when she took off from Lae, so she couldn’t hear anybody on 320/56210 kc.
    The part I especially liked was the interview of Betty Klenck who I tend to believe. This antique radio group certainly seemed to think it was possible for Betty to pick up Amelia. I also think that Betty was not hearing “Norwich City” but heard “Nonouti” (my interpretation). Of course she thought it was NY City.
    I don’t know why Ric Gillespie plays a part in this video, but just tune him out and listen to the rest of the story.


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