6210, 3105, 500 kc

CXCIX

 

 

Radio was hardly newfangled by 1937, but it remained relatively rare aboard all but long-distance aircraft. The big metal boxes, loaded with glass tubes, miles of wire, and ceramic resistors galore, weighed a ton and to save weight most short- to medium-haul airlines refused to use anything but the most basic navigational radio devices. Voice-to-voice communication was still considered a luxury. 

Amelia insisted on voice-to-voice capability. She had used it to great effect during her solo transatlantic flight, and the sense of not being alone provided her a great psychological boost during the long legs of her flights. The Flying Laboratory, almost by definition, needed the most advanced radio equipment available to pilots, including voice-to-voice. 

On the first Worldflight she had used Western Electric radio gear. At the time the second Worldflight was scheduled, the Electra retained the same Western Electric hardware. Amelia seemed bizarrely averse to familiarizing herself with her own radio gear. She dodged practice sessions by attending public relations events. She let planning meetings run late and cut into her time with the radio techs. She refused to “strain” the Electra’s brand-new engines, hardly using them in routine ground-based full-power static tests of the equipment. It was all very odd for a planetary adventurer. 

She was just as lax when it came to radio protocols. She believed that everyone would be using Greenwich Mean Time as a timekeeping standard for communications, but neglected to confirm this simple assumption. In fact, most places used Local Time, including the U.S.S. Itasca. This oversight would lead to endless confusion in the aftermath of the thing.

She did not practice using her Morse Code keyboard (though Fred Noonan had skill with Morse). For keeping in contact with the outside world she used the AM radio frequencies preset into the machinery at the factory. She failed to learn the frequencies at which her Radio Direction Finder operated at peak efficiency and those at which it hardly functioned at all. 

Amplitude Modulation (AM) had inherent shortcomings anyway. Highly affected by atmospheric conditions, communications could be lost to static in bad weather or because of sunspots especially. Signal strength and distance could vary wildly between day and night (as a rule, AM transmitters used one set of frequencies at night and another set during the daytime). “Skip” (in which a radio signal could bounce off a dense patch of atmosphere) could lead to unusual phenomena.* Amelia Earhart seemed willfully blind to anything but the “plug-and-play” aspects of her radio. 

George Putnam, hardly a radio expert, not only selected the frequencies Earhart would use during the second Worldflight, but he put himself in charge of advising the various staging stops and ground stations about them. 

Here too, there was confusion. Some of George’s memoranda didn’t reach their intended recipients at all, and some miscarried until Earhart had come and gone from the place. Some of the stations confused her nighttime frequency with her daytime frequency. Some of the stations had difficulty picking up her selected frequencies altogether and relied on her backup emergency frequency to communicate with her. She was forced to monitor all three frequencies at once, and so she channel-hopped around the dial in seeming chaos trying to keep track of who, what, where, and when.

The “Miami photo” showing the cockpit of the Electra 10E Special in June 1937.  The large box in the upper left hand corner is posited by most to be a communications device; during the first Worldflight crash, Amelia had bumped her head on the same or a similar device. During the stay in Miami, the on-board Western Electric radio equipment was replaced with Bendix equipment, but whether this picture was taken before or after the refurbishing is unclear. TIGHAR (pronounced “Tiger”), The International Group for Historic Aircraft Recovery, argues that the replacement never took place. TIGHAR also argues that Earhart’s radio was even less technically advanced than believed, and that Earhart and Noonan made a safe landfall but died subsequently. To date, this blogger remains unconvinced but not skeptical   

 

In the event, messages were missed and scrambled. Her overwhelming reliance on voice-to-voice risked the very real chance of garbling. Voice transcription errors by radiomen abounded, especially in regions where English was not the primary tongue.  

As if this were not all confusing enough, upon her arrival at Pan American Field (now Miami International Airport), Pan Am’s technicians gave the essentially brand-new plane a thorough overhaul, resetting everything to Pan Am Standard, including the radio. Before Earhart and Noonan left Miami, however, representatives of the Bendix Corporation tore out all of the Western Electric electronics, replacing it all with Bendix. It was purely a marketing ploy --- that, and Bendix had paid George Putnam an impressive $5000.00, over and above the free radio gear, to install their brand aboard the Flying Laboratory. 

The Bendix equipment worked differently than the Western Electric equipment. It had different tolerances and the efficiency of frequencies sent and received varied from Western Electric’s gear. 

The Bendix RA-1 transmitter was used widely by the U.S. Navy. There were five receiver bands, marked 1-5 on Earhart’s machine. There were also five separate RDF bands also marked identically 1-5. The RDF bands and the receiver bands worked on very different frequencies. Harry Manning, with his Merchant Marine and Naval connections, was familiar with the Bendix RA-1. He might have alerted Amelia to the critical difference between the voice-to-voice and RDF bands, but either he did not or it did not make an impression upon her. In any event, by the time the Bendix was installed in the Electra he was off the Worldflight project entirely. Bendix did not supply a user’s manual. 

RDF of the time tended to go “flat” at certain bandwidths; the efficiency of a given bandwidth depended to a surprising degree on the engineering of the equipment. Industry standards tended to be adhered to more in the breach until World War II combat conditions demanded across-the-board consistency. Thus, there could be (and would be) marked differences in the quality of a Bendix signal versus a Western Electric signal versus any other company. Time, and the simple habit of use allowed pilots to become comfortable with the “best” frequencies for their own planes. 

Earhart had minimal practical (“normal use”) experience with the Western Electric 13C / 20B receiver-transmitter, but even with some practical experience the radio gear was only minimally contrived to handle a Worldflight (like the rest of the Electra, the radio wasn’t designed for long-distance continuous usage). The radio design dated from 1934, and was rated for only a relatively weak 50 watts which made it hard for a ground station to lock on to a signal and likewise did not provide a sturdy RDF platform. It had double doubled-over antennas that ran from the RDF loop backward to the twin rear stabilizers. The plane also had originally had a trailing antenna that could be reeled in and out through the use of a crank on the cockpit floor, but it was removed before the second Worldflight.

Bendix replaced all the radio gear aboard during the Miami layover (this had been open to question for years, but recent rediscovered correspondence and photographs confirm it). The Bendix gear was considered military grade but  it was not substantially more effective or efficient to use than the Western Electric gear --- there was nothing much groundbreaking about it, though it would have been the gold standard of the time for a private pilot (though not for a commercial pilot or a world-renowned record-breaker).  The reality is that Amelia could have had Skype on board for all it mattered since she spent literally no time learning how to use her transmitter.

The issue of equipment aside, and the issue of miscommunications prior to flight mooted by events, Amelia Earhart relied on two primary frequencies to communicate ---  3105 kilocycles (nighttime) and 6210 kilocycles (daytime), with a backup at 500 kilocycles (the 500 kc band, which the Itasca and Howland Island were both configured to hear best,   worked best with the now-absent reel antenna). 

Completely fogging the issue of the radio and its functionality, Bendix installed a hardware upgrade of some type while Earhart and Noonan were on layover at Lae, New Guinea, their last recorded landing site. It is not entirely clear what the new gear was enabled to do, but given Earhart’s cavalier attitude toward her best lifeline it is a certainty that she didn’t bother to learn anything about the new gizmo Bendix had gifted her with.

*As a youngster, this blogger, a New Yorker, had a multiband radio that could pick up airliner communications and during a severe thunderstorm overheard a pilot speaking to LAX --- a classic example of atmospheric skip. There are many mysteries surrounding the second Worldflight, and that statement applies particularly to its final leg. It is difficult to determine even which manufacturers provided the equipment that flew aboard the Electra. Earhart was singularly bad at documenting events even though she could make them into a good story, and eighty years later it is often impossible to determine the whys and wherefores of events and even the precise whens.  Note that this post keeps to an absolute minimum the physics of radio. Although it determined Amelia Earhart’s fate, the subject is, as Amelia herself might have admitted, dry to the point of aridity. Since we readers are not at risk of our lives for not knowing a kilocycle from a Megahertz, I leave defining the terminology for another day. Any technical errors in the text are purely mine.