Simplexity Aloft

Copyright ©2010 by Paul Niquette. All rights reserved.
Readers will recognize at once that without audio recordings the accuracy of the communications reports will be forever kept in doubt  Difficulties in understanding the words in noisy radio transmissions was only the beginning.  Whole chapters in Amelianna are devoted...
  • to the error-prone transcription process, 
  • to erasures and overtyping ("smoothing the reports"), 
  • to the skills of low-ranking operators unfamiliar with aviation's phraseology, 
  • to after-the-fact re-writing by persons having a stake in investigations to come, and
  • to the inevitable pilfering of historical souvenirs from the Itasca radio room. 
With all these realities in mind, let us take up the challenge in the Simplexity Aloft  puzzle -- parsing the last words of Amelia Earhart (AE) as they were reported in the ITASCA Radio Room Transcript July 2, 1937...
 
0615 WANTS BEARING ON 3105 KCS / ON HOUR / WILL WHISTLE IN MIC. ABOUT TWO HUNDRED MILES OUT // APPX // WHISTLING.
This 0615 IST transmission would have been initiated aboard the Electra at 1745 GCT, which was in keeping with the pre-arranged 'radio schedule' according to which AE was supposed to transmit simplex at quarter-to and quarter-passed each hour. 

The phraseology "WANTS BEARING..." is in the third person in place of what was surely  heard over-the-air in the form of a request, "PLEASE TAKE BEARING ON US..." (as repeated a half-hour later at 0645 IST), thus AE was invoking Half-Duplex RDF, intending to obtain guidance from Itasca ('DF steer'). 

The "ON 3105 KCS" part of the message may seem to be redundant (tantamont to saying, "listen to me on the frequency on which you are now listening to me"), but it calls attention to a critical issue. 

Critical Issue {1}:  As mentioned in the puzzle,  three different radio frequencies would be called out by AE (3105, 6210, and 7500 KCPS). 
The table in the puzzle shows that, if everybody stuck to the script, those time-slot assignments with  IST = GCT minus 11:30 ought to have worked without conflict.  Although not shown explicitly in the puzzle, simultaneous streams on all frequencies were being transmitted during the time-slots assigned to Itasca.

Solvers should take note that in the 0615 IST transmission, we see the phrase "ON HOUR," which was a mere confirmation of the schedule -- but only as perceived by AE.

Critical Issue {2}: Fifteen minutes after 1745 GCT, the time on board the Electra would read 1800 GCT, which is indeed "ON HOUR"; however, that time would be read on board Itasca as "0630 IST," thus on the "half-hour." 
Taken literally, AE's request was for Itasca to transmit the RDF bearing back to the Electra at 0700 IST, fully 45 minutes later, during which the Electra would have travelled more than 100 miles on an uncorrected heading.

The clause "WILL WHISTLE IN MIC" receives considerable attention in references about the flight.  Conventional procedure for Half-Duplex RDF is for the pilot to key his or her microphone and count forwards then backwards while the operator on the ground turns his or her loop antenna to obtain a 'null' for the bearing.  Several authors express the opinion that AE used her voice at high pitch to simulate an audio tone heard in Morse Code. 

The phrase "// APPX // WHISTLING" probably is another case of using the third person to describe events in the transcript.  However, we are reminded again of something potentially more significant.

Critical Issue {3}: According to some references, AE did not understand Morse Code.  Others aver that both AE and FN were competent with radiotelegraph, but preferred radiotelephone instead.
"ABOUT TWO HUNDRED MILES OUT" may be a direct quote from AE.  Given that the Electra took off at 0000 GCT with 22 hours of fuel, we surmise that the flight would touch down with two hours of fuel remaining.  Not a critical issue for Simplexity Aloft.
0645 PLEASE TAKE BEARING ON US AND REPORT IN HALF HOUR  / I WILL MAKE NOISE IN MICROPHONE -- ABOUT 100 MILES OUT.
Thirty minutes later, right on schedule, the message received at 0645 IST  would have been initiated by AE at 1815 GCT. 

The phrase "PLEASE TAKE BEARING ON US" was consistent with the 0615 IST transmission, as AE continues to invoke Half-Duplex RDF, obtaining guidance from the ground ('DF steer').   At this point sophisticated solvers are able to identify another critical issue.

Critical Issue {4}: No acknowledgment is present in the transcript that AE had received a bearing from Itasca in response to her 1745 GCT request a half- hour earlier. 
It is altogether reasonable that AE would have said something to the effect "WE RECEIVED YOUR TRANSMISSION, AS ADVISED WE HAVE TAKEN UP A HEADING OF ZERO NINER ZERO."

Apparently unknown to AE, the radio operators on board Itasca did not have the appropriate RDF equipment to take bearings from AE's signals on the frequency she was using,  3105 KCS.   Of course, the operator in the radio room would have made no secret of that inability during Itasca's transmitting time-slot at 0630 IST, and therefore AE should have received that unhappy news at 1815 GCT or more likely earlier.  Accordingly, the absence of an acknowledgement in critical issue {4} provides indirect evidence of something more general to concern us.

Critical Issue {5}: Transmissions from Itasca on 3105 KCS cannot be received by the Electra.  Not knowing that, AE goes ahead and tries again.
With her request recorded at 0645 IST, we observe the gratuitous phrase "REPORT IN HALF HOUR" not "REPORT ON HALF HOUR." This could be the result of a transcription error, of course; however, we must characterize it as a critical issue in our solution.
Critical Issue {6}: On board Itasca, "IN HALF HOUR" means transmitting the RDF response at 0715 IST, which is at the beginning of the Electra's next transmission slot and a violation of the pre-arranged radio schedule.  If AE really said. "ON HALF HOUR," the RDF response from Itasca would not be transmitted until 0730 IST, which is delayed a full 45 minutes.
Another interpretation of the issue may be supported by the absence of AE's 1845 GCT transmission, implying that, she indeed meant "IN" not "ON," an apparent ad hoc adjustment to the radio protocol that invited Itasca to transmit in her time-slot. 

For unknowable reasons, AE changed from "WILL WHISTLE IN MIC" to "I WILL MAKE NOISE IN MICROPHONE," possible on the assumption that her attempt a half-hour earlier had failed.  If so, AE may have also decided to allow more time for the RDF to be processed. 

The estimate "ABOUT 100 MILES OUT" at 1815 GCT would be doubtful, given previous estimate of "ABOUT TWO HUNDRED MILES OUT" only thirty minutes earlier at 1745 GCT.  Solvers of the Wages of Flight puzzle will probably not classify this is a critical issue for Simplexity Aloft

0742 KHAQQ CALLING ITASCA WE MUST BE ON YOU BUT CANNOT SEE YOU BUT GAS IS RUNNING LOW UNABLE REACH YOU BY RADIO WE ARE FLYING AT ALTITUDE 1000 FEET.
The most mysterious attribute of AE's transmission at 1912 GCT (0742 IST) is that it came over the air almost a full hour after the her previous transmission, having skipped her transmission scheduled for 1845 GCT (0715 IST) and taking up part of the time interval assigned to Itasca for transmitting. 
Critical Issue {7}: The simple fact that the message was logged in the Itasca radio room at 0742 IST means that operators in the radio room were listening not transmitting on 3105 KCS during the time slot assigned to Itasca
The urgency for AE to get back on the radio is implied by the wishful message, "WE MUST BE ON YOU BUT CANNOT SEE YOU."  No mention is made of clouds or limited visiblity.  Still, the passage raises the question, Why did AE wait for an extra half-hour before calling? 

A speculative answer may be present in the sentence "WE ARE FLYING AT ALTITUDE 1000 FEET," which suggests that AE may have been distracted from radio direction finding while engaged in the descent from cruise altitude (possibly through a cloud deck).

Here again, we see evidence of the most serious difficulty faced by AE in the phrase, "UNABLE REACH YOU BY RADIO"  (see critical issue {5} above).

The fuel consumption rate was higher than planned as the result of realities that will be well understood by solvers of Live Reckoning.  Nevertheless, less than 20 hours earlier, the electra had taken off with 22 hours of fuel on board.  AE's worrisome statement "GAS IS RUNNING LOW" probably does not qualify as a critical issue for our solution to Simplexity Aloft.  It is not too unlikely that AE was trying by those words to intensify the pressure on the radio operators on board Itasca.  Either that or she was just thinking out loud.

0758 KHAQQ CALLING ITASCA -- WE ARE CIRCLING BUT CANNOT HEAR YOU GO AHEAD ON 7500 EITHER NOW OR ON THE SCHEDULE TIME ON HALF HOUR.
The transcript logged this message at 0758 IST or 1928 GCT -- just two minutes before the end of AE's time slot for transmitting and 16 minutes after the previous transmission, which had 'stepped on' Itasca's transmission schedule. Whether these times are correct we cannot know.  More than confusion is in play.  Specifically, there needed to be extra intervals of radio silence on board Itasca to allow operators to listen for transmissions from AE on board the inbound Electra.

Almost certainly the statement "WE ARE CIRCLING BUT CANNOT HEAR YOU" was taken down in error.  "Circling" does not make sense according do Gillespie.  Instead the passage should have been corrected to read "WE ARE LISTENING BUT CANNOT HEAR YOU."   If so, that is a devastating reminder of critical issue {5} above.

The next request "GO AHEAD ON 7500" indicates a peremptory change in frequency by Amelia Earhart and another source of confusion.

Critical Issue {8}: The "go ahead" could refer to the frequency for listening by Itasca to hear audio "noise" (formerly "whistling"), but "go ahead" could more likely refer the frequency for Itasca to use in responding with the RDF bearing.
The request includes "EITHER NOW OR ON THE SCHEDULE TIME ON HALF HOUR," whereby "now" would be at 0758 IST, which is two minutes before "the schedule time," but that would be "on the hour" 0800 IST as read on Itasca clocks not the "half hour" 1930 GCT as seen by AE on board the Electra.  Nom et ipsa, this part of the transmission by itself would not  indicate a critical issue, inasmuch as two minutes later AE called again on 3105 KCS -- stepping on another time-slot assigned to Itasca.
0800 KHAQQ CALLING ITASCA WE RECEIVED YOUR SIGNALS BUT UNABLE TO GET A MINIMUM PLEASE TAKE BEARING ON US AND ANSWER 3105 WITH VOICE.
For the first time AE is able to say "WE RECEIVED YOUR SIGNALS" (presumably on the new frequency 7500 KCS).  Notice that's "signals" not necessarily "words" or "voice."  Itasca was able to send only code on 7500 KCS. By pre-arrangement before the flight, Morse Code for the letter "A" (dot-dash) was to be repeated over and over, intended to surmount critical issue {3} and enable Receive-Only RDF.

One resource, TIGHAR, offers an intriguing explanation for the loss of radio reception on board the Electra and thus RDF .  As indicated in the cutaway diagram below, supposedly a "belly antenna" was needed for receiving radio communications.  Film evidence has been discovered suggesting that the antenna was torn off during the take-off roll at Lae.  Other experts, especially Rafford, say instead that the V-antenna on the mast atop the aircraft was used for both sending and receiving.  Let us take AE's 1930 GCT transmission, which included the passage, "WE RECEIVED YOUR SIGNALS," as confirmation.

The full sentence "WE RECEIVED YOUR SIGNALS BUT UNABLE TO GET A MINIMUM" implies that AE had suddenly switched from Half-Duplex RDF and was attempting to accomplish Receive-Only RDF, which calls for receiving the 7500 KCS signal using the Electra's loop antenna "to get a minimum" for a bearing. 

Solvers will note that only two minutes had elapsed (0758 - 0800 IST) since AE's request to GO AHEAD ON 7500 -- only two minutes to GET A MINIMUM on a different frequency (7500 KCS,changing from 3105 KCS). 

Critical Issue {9}: Amelia Earhart failed to achieve Receive-Only RDF.
Apparently unknown to -- or unremembered by -- Amelia Earhart, the loop antenna aboard the Electra was designed for 'low frequencies' -- 250 to 500 KCS not 7500 KCS, as explained by Paul Rafford and others. An endless string of dot-dashes (not a DF steer by Morse Code) would have been useless on board the Electra.

AE returns to Half-Duplex RDF with the statement "PLEASE TAKE BEARING ON US AND ANSWER 3105 WITH VOICE."  The dire truth: Half-Duplex RDF had not worked for more than two hours; there was no reason to expect it would work now.  Or ever.

0843 WE ARE ON THE LINE OF POSITION 157-337, WILL REPEAT THIS MESSAGE, WE WILL REPEAT THIS MESSAGE ON 6210 KCS.  WAIT LISTENING ON 6210 KCS. . . WE ARE RUNNING NORTH AND SOUTH.
Parsing Amelia Earhart's last transmission at 0843 IST (2013 GCT)...
  1. WE ARE ON THE LINE OF POSITION 157-337 ~~ An incomplete position report, given that the sun LOP stretches both north and south of Howland, then...
  2. WILL REPEAT THIS MESSAGE ~~ An awkward redundancy, as it might have pertained to 3105 KCS, were it not interrupted by...
  3. WE WILL REPEAT THIS MESSAGE ON 6210 KCS ~~ An abrupt change in the Electra's frequency, which is condradicted by its being transmitted on 3105 KCS;
  4. WAIT LISTENING ON 6210 KCS ~~ An unnecessary request inasmuch as Itasca would be transmitting on all frequencies during its assigned time-slot, and finally...
  5. WE ARE RUNNING NORTH AND SOUTH.~~ An ambiguous -- indeed -- an impossible flight maneuver and altogether useless for guiding subsequent searches.

Some authors (and I) have speculated that the last line in Amelia Earhart's last radio transmission was transcribed in error -- that she really said...
WE ARE RUNNING ON LINE NORTH NOT SOUTH.
Critical Issue {10}: Amelia Earhart was woefully uninformed about the operation of her radios both for navigating and communicating.  Or something else...
For our solution to the Simplexity Aloft puzzle...
 
We have identified at least ten critical issues
in Amelia Earhart's six final radio transmissions.

...which taken together provide more than enough causes for the utter failure in radio communications during the last two and a half hours of the flight. 

The expression "more than enough" should raise suspicions. Arguably the researcher with the best credentials, Paul Rafford, Jr., has used evidence obtained over seven decades from contemporaneous sources for his own speculations in Amelia Earhart’s Radio: Why She Disappeared.   Rafford suggests...

  • That the confusion in Earhart's radio work was intentional.
  • That both simplex and half-duplex RDF were deliberately defeated.
  • That Earhart and Noonan had a destination other than Howland.
  • That the Electra would be concealed from all the inevitable searches.
  • That Earhart and Noonan would therefore not be immediately found.
Cynics might argue that the whole round-the-world trip was a publicity stunt and thus presumably augmented by a massive deception, which went horribly wrong.  A more solemn motivation is favored by many -- that Earhart and Noonan had heroic rôles to play in the nation's run-up to World War II in the Pacific.  We will leave those puzzles for others.  Available to guide such endeavors are huge amounts of speculative literature, some considering -- but most neglecting -- the technical and historical findings which have been studied in Simplexity Aloft.

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