Catalog and Analysis of Radio Signals
During The Search for Amelia Earhart in July 1937

Compiled and edited by Bob Brandenburg, TIGHAR #2286R
and
Ric Gillespie, Executive Director
Signals July 4

The Signal Identifier number is divided into these elements:

Day Time Source
4 0620 CC
(July) 24hr List

  • Identifiers in BLUE are TRANSMISSIONS to Earhart.
  • Identifiers in RED are reported receptions that are judged to be NOT CREDIBLE.
  • Identifiers in BLACK are reported receptions the credibility of which are judged to be UNCERTAIN.
  • Identifiers in GREEN are reported receptions that are judged to be CREDIBLE.

48–4xxxxMY 49–40620CC 50–40645IA 51–40650HD 52–40653IA 53–40720BR 54–40833KU 55–40834PU 56–40850IA 57–40851IA
58–40854IA 59–40936IA 60–41000KB 61–41005IA 62–41012PU 63–41022PU 64–41031PU 65–41031PU 66–41035CC 67–41037IA
68–41057IA 69–41059IA 70–41110PU 71–41114IA 72–41122IA 73–41127IA 74–41200CC 75–41153CV 76–41200CC 77–41215WD
78–41200DN 79–41330MC 80–41437PY 81–41500RH 82–41500CB 83–41512PY 84–41523PU 85–41553PY 86–42100IA 87–42130IA
88–42200IA 89–42230IA 90–42300IA 92–42330IA            
48
Identifier 4xxxxMY
Z Time/Date Time(s) unknown, July 4
Local Time/Date Time(s) unknown, July 4
Gardner Time/Date Time(s) unknown, July 4
Agency/Person Ray Mahoney, radio amateur
Location Cincinnati, Ohio
Freq (kHz) unknown
Content Mahoney said he heard Earhart “pleading for help” from a position he assumed to be within 57 miles of Howland Island. He said “The signals were weak, about all I could make out were the call letters of her plane, that apparently had hit a reef or was near a reef.” He said he had heard the distress signals at 10 minutes intervals throughout “yesterday,” which was Saturday, July 3.
Source Associated Press wire story in Gettysburg, PA, Times, July 5, 1937, p.2; Associated Press wire story in Newark, OH, Advocate, July 5, 1937, p.1; Finding Amelia, p.171.
Probability Not computed because specific times and frequencies not given. But continuous reception “throughout yesterday” on any given single frequency was impossible.
Qual Factors There is no reef within 57 miles of Howland. It would be implausible for Earhart to transmit at 10 minute intervals “throughout yesterday” since doing so would entail the risk of dropping the battery charge below the level needed to start the engine, thus precluding future radio transmissions. Furthermore, propagation conditions precluded receiving signals during such a long period.
Credibility Not credible
49
Identifier 40620CC
Z Time/Date 0620 to at least 0846 July 4
Local Time/Date 1950 to at least 2216 HST July 3
Gardner Time/Date 1920 to 2146 July 3
Agency/Person Coast Guard Commander, Hawaiian Sector (COMHAWSEC)
Location Honolulu
Freq (kHz) 3105
Content COMHAWSEC advised Itasca that a weak carrier (unmodulated) signal had been heard on 3105 kHz, and that the Pan American Airways direction finder station at Mokapu also heard the signal but was unable to get a bearing on the source.
Source MSG8.PDF, p. 351
Probability 0.024
Qual Factors The signal could have originated at Gardner. However, west coast aircraft can’t be ruled out since this time period was during night there, and aircraft would be using 3105 kHz. There is insufficient evidence to decide where the signal probably originated.
Credibility Uncertain.
50
Identifier 40645IA
Z Time/Date 0645 July 4
Local Time/Date 1915 July 3
Gardner Time/Date 1945 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3110 kHz
Content Itasca logged hearing a weak signal with possible voice modulation on 3110 kHz.
Source RADREST.PDF, p. 151
Probability 0.87
Qual Factors There were no voice signal sources on 3110 kHz. Howland Island received a credible signal from Earhart five minutes later. It is possible that Itasca’s receiver was not correctly set.
Credibility Uncertain
51
Identifier 40650HD
Z Time/Date 0650 July 4
Local Time/Date 2020 HST July 3
Gardner Time/Date 1950 July 3
Agency/Person Amateur radio operator
Location Howland Island
Freq (kHz) 3105 kHz. (Assumed. Not stated in report)
Content The Howland amateur operator informed Itasca – in a delayed report at 09:46 Z on July 5 – that the amateur radio operator on Baker Island (30 miles south southeast of Howland) had heard Earhart with a strong and clear signal, at the time shown above but did not state the content of the transmission.
Source RADREST.PDF, p. 174. (Note: the final phrase of this record – in which the signal characteristics are given – inadvertently appears as the first phrase of the record at the top of p. 175.)
Probability 0.96
Qual Factors The signal strength is consistent with a transmission from Gardner. And the operator was unequivocal about hearing Earhart.
Credibility Credible
52
Identifier 40653IA
Z Time/Date 0653 July 4
Local Time/Date 1923 July 3
Gardner Time/Date 1953 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3110
Content Itasca heard the same signal as #40650HD above, very weak.
Source RADREST.PDF, p. 151
Probability 0.96
Qual Factors There were no voice signal sources on 3110 kHz. Howland Island received a credible signal from Earhart three minutes prior (Signal 51). It is possible that Itasca’s receiver was not correctly set.
Credibility Uncertain
53
Identifier 40720BR
Z Time/Date 0720 July 4
Local Time/Date 2020 July 3
Gardner Time/Date 2020 July 3
Agency/Person Amateur radio operator Paul Yat Lum
Location Baker Island
Freq (kHz) 3105
Content The Earhart plane was heard, signal Strength 4 (5 being maximum), Readability 7 (10 being maximum). Details not given. The fact of the reception was relayed to Itasca by the Coast Guard detachment on Howland Island.
Source RADREST.PDF, p. 174 and 175; Finding Amelia, p.134.
Probability 0.85
Qual Factors The signal source was positively identified as the Earhart plane.
Credibility Credible
54
Identifier 40833KU
Z Time/Date 0833 July 4
Local Time/Date 2203 HST July 3
Gardner Time/Date 2133 July 3
Agency/Person Radio Station KGU
Location Honolulu
Freq (kHz) 750
Content KGU broadcast a message to Earhart, requesting her to transmit on 500, 3105, or 6210 kHz.
Source TIGHAR Earhart Project Research Paper “The Itasca Search.”
Probability n/a
Qual Factors n/a
Credibility n/a
55
Identifier 40834PU
Z Time/Date 0834 July 4
Local Time/Date 2204 July 3
Gardner Time/Date 2134 July 3
Agency/Person Pan American Airways radio direction finding station
Location Mokapu Point, Oahu
Freq (kHz) 3105
Content Immediately following the KGU broadcast at 0833Z, the Pan American station at Mokapu heard a faint carrier on approximately 3105 kHz, but the signal was too weak to distinguish any words.
Source Memorandum from Pan American Airways Communications Section Supervisor, Honolulu, to Division Superintendent, Communications, Alameda dated July 10, 1937.
Probability 0.0009
Qual Factors The reception probability at Mokapu was consistent with the signal description. Honolulu broadcast stations could be heard throughout the central Pacific, and the fact that the signal came immediately after the KGU request suggests this was Earhart responding. It is possible that this carrier signal was from one of the Nicaraguan stations, but the preponderance of positive qualitative factors weighs in favor of concluding that the signal was from Earhart.
Credibility Credible
56
Identifier 40850IA
Z Time/Date 0850 July 4
Local Time/Date 2120 July 3
Gardner Time/Date 2150 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content A weak carrier was heard, but no voice. Itasca heard this weak carrier continuously until 1300Z on July 4.
Source RADREST.PDF, p. 153, et seq.
Probability 0.91
Qual Factors Although the probability of receiving a signal from Gardner was high, it is not plausible for Earhart to have her transmitter on the air for such a long time. It is possible that Itasca was hearing the carrier of one of the Nicaraguan stations.
Credibility Not credible
57
Identifier 40851IA
Z Time/Date 0851-0854 July 4
Local Time/Date 2121-2124 July 3
Gardner Time/Date 2151-2154 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) near 3105
Content Itasca heard two carrier signals, but no voice, near 3105 kHz on slightly different frequencies, one slightly stronger than other but both very weak.
Source RADREST.PDF, p. 152
Probability 0.92
Qual Factors Not more than one of these signals could be from Earhart. One or both could have originated in Nicaragua. There is not sufficient evidence to conclude that either of these signals was from Earhart.
Credibility Uncertain
58
Identifier 40854IA
Z Time/Date 0854-0929 July 4
Local Time/Date 2124-2159 July 3
Gardner Time/Date 2154-2229 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105 (approximately)
Content Heard one carrier continuously during this period.
Source RADREST.PDF, p. 152
Probability 0.92
Qual Factors It was not plausible for Earhart to key her transmitter continuously for such a long period. Itasca could have been hearing one of the Nicaraguan stations.
Credibility Not Credible
59
Identifier 40936IA
Z Time/Date 0936-0952 July 4
Local Time/Date 2206-2222 July 3
Gardner Time/Date 2236-2252 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105 approximately
Content Itasca still hears a continuous carrier near 3105 kHz, very weak, in severe atmospheric noise.
Source RADREST.PDF, p. 153
Probability 0.92
Qual Factors It was not plausible for Earhart to key her transmitter continuously for such a long period. Itasca could have been hearing one of the Nicaraguan stations.
Credibility Not credible
60
Identifier 41000KB
Z Time/Date 1000 July 4
Local Time/Date 2330 HST July 3
Gardner Time/Date 2300 July 3
Agency/Person Broadcast station KGMB
Location Honolulu
Freq (kHz) 1320
Content KGMB broadcast a message to Earhart requesting her to transmit dashes.
Source TIGHAR Earhart Project Research Paper “The Itasca Search.”
Probability n/a
Qual Factors n/a
Credibility n/a
61
Identifier 41005IA
Z Time/Date 1005 to 1029 July 4
Local Time/Date 2235 to 2259 July 3
Gardner Time/Date 2305 to 2329 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca still hears a carrier signal on 3105 kHz, but very weak now.
Source RADREST.PDF, p. 152
Probability 0.91
Qual Factors It was not plausible for Earhart to key her transmitter continuously for 24 minutes. Itasca could have been hearing one of the Nicaraguan stations.
Credibility Not credible
62
Identifier 41012PU
Z Time/Date 1012-1020 July 4
Local Time/Date 2342-2350 HST July3
Gardner Time/Date 2312-2320 July 3
Agency/Person Pan American Airways Radio direction finding station
Location Mokapu Point, Oahu
Freq (kHz) 3105
Content Intermittent carrier signals were heard, but no voice.
Source Pan Am memo from Section Supervisor, Communications, Honolulu to Division Superintendent, Communications, Alameda dated July 10, 1937.
Probability 0.0082
Qual Factors The Pan Am description of this signal is vague, although an Associated Press story of July 5 stated that Honolulu radio station KGMB had requested Earhart to turn her transmitter on and off four times, and that the Pan Am listening station at Mokapu Point had heard four distinct dashes in response. The timing and characteristics of this signal might suggest it was from Earhart, in response to the KGMB request, but the possibility that the source was in Nicaragua cannot be ruled out.
Credibility Uncertain
63
Identifier 41022PU
Z Time/Date 1022 July 4
Local Time/Date 2352 HST July 3
Gardner Time/Date 2322 July 3
Agency/Person Pan American Airways Radio direction finding station
Location Mokapu Point, Oahu
Freq (kHz) 3105
Content Two long dashes – possibly voice transmissions – were heard on 3105.
Source Pan Am memo from Section Supervisor, Communications, Honolulu to Division Superintendent, Communications, Alameda dated July 10, 1937.
Probability 0.0055
Qual Factors The timing of the dashes suggests they were sent by Earhart in response to the 1000Z KGMB broadcast. Earhart was the only plausible source of voice signals on 3105 kHz in the central Pacific.
Credibility Credible
64
Identifier 41031PU
Z Time/Date 1031 July 4
Local Time/Date 0001 July 4
Gardner Time/Date 2331 July 3
Agency/Person Pan American Airways radio direction finding station
Location Mokapu Point, Oahu
Freq (kHz) 3105
Content The U.S. Navy radio station at Wailupe, Oahu, heard a carrier on the air for a short time, and heard a male voice say “31,” but the rest of the transmission was unreadable. The Pan Am station heard a carrier at the same time, but no voice.
Source Memorandum from Pan Am Section Supervisor, Communications, Honolulu to Division Superintendent, Communications, Alameda dated July 10, 1937. Wailupe evidently passed this information by telephone to Mokapu, and also to the Coast Guard commander in Honolulu (COMHAWSEC), who relayed it to the Itasca.
Probability 0.004
Qual Factors Earhart’s transmitter was the only credible voice source on 3105 kHz in the central Pacific. The timing of this signal suggests it could be a response to the KGMB broadcast at 1000Z.
Credibility Credible
65
Identifier 41031PU
Z Time/Date 1031-1100 July 4
Local Time/Date 0001-0030 July 4
Gardner Time/Date 2331-2400 July 3
Agency/Person Pan American Airways radio direction finding station
Location Mokapu Point, Oahu
Freq (kHz) 3105
Content The carrier previously heard comes and goes, increasing somewhat in strength, but atmospheric noise is getting much worse and reception is still too poor to try a bearing.
Source Memorandum from Pan Am Section Supervisor, Communications, Honolulu to Division Superintendent, Communications, Alameda dated July 10, 1937.
Probability 0.0076
Qual Factors The timing of this signal, and its intermittent nature, are consistent with dashes responding to the KGMB broadcast at 1000Z. But it also is possible the source was a Nicaraguan station.
Credibility Uncertain
66
Identifier 41035CC
Z Time/Date 1035 July 4
Local Time/Date 0005 July 4
Gardner Time/Date 2335 July 3
Agency/Person Coast Guard Commander, Hawaiian Sector (COMHAWSEC)
Location Honolulu
Freq (kHz) 3105
Content COMHAWSEC informed Itasca that the Navy radio station at Wailupe, the Pan Am direction finding station at Mokapu, and COMHAWSEC, all heard a carrier and voice on 3105 kHz at the end of the KGMB broadcast requesting Earhart to send dashes. (Note: Pan Am Mokapu said they did not hear voice.)
Source MSG8.PDF, p. 351
Probability 0.004 at Honolulu
Qual Factors The timing of this signal, and its intermittent nature, are consistent with dashes responding to the KGMB broadcast at 1000Z. Earhart’s transmitter was the only plausible source of voice signals on this frequency in the central Pacific.
Credibility Credible
67
Identifier 41037IA
Z Time/Date 1037 to 1055 July 4
Local Time/Date 2307 to 2329 July 3
Gardner Time/Date 2337 to 2355 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105 kHz
Content Itasca still hears a continuous weak carrier on 3105 kHz.
Source RADREST.PDF, p. 154
Probability 0.44
Qual Factors This appears to be a continuation of the long-duration carrier reported by Itasca above, possibly from Nicaragua. It is not plausible for Earhart to have keyed her transmitter continuously for 19 minutes.
Credibility Not credible
68
Identifier 41057IA
Z Time/Date 1057 July 4
Local Time/Date 2327 July 3
Gardner Time/Date 2357 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca hears a weak unreadable Morse code signal, shifting in frequency, very close to 3105 kHz.
Source RADREST.PDF, p. 154
Probability 0.74
Qual Factors Neither Earhart nor Noonan was proficient in Morse code. Furthermore, Earhart’s transmitter frequency was crystal-controlled, and did not drift.
Credibility Not credible
69
Identifier 41059IA
Z Time/Date 1059 July 4
Local Time/Date 2329 July 3
Gardner Time/Date 2359 July 3
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca still hears the weak carrier, shifting in frequency (Identifier 41012PU above), but the Morse code signal has stopped.
Source RADREST.PDF, p. 155
Probability 0.74
Qual Factors Earhart’s transmitter frequency was crystal-controlled, and did not drift.
Credibility Not credible
70
Identifier 41110PU
Z Time/Date 1110 July 4
Local Time/Date 0040 July 4
Gardner Time/Date 0010 July 4
Agency/Person Pan American Airways Radio direction finding station
Location Mokapu Point, Oahu
Freq (kHz) 3105
Content A signal sounding like someone trying to send Morse code, but nothing readable.
Source Memorandum from Pan Am Section Supervisor, Communications, Honolulu to Division Superintendent, Communications, Alameda dated July 10, 1937.
Probability 0.0076
Qual Factors Neither Noonan nor Earhart was proficient in Morse code. This signal could have been one of the Nicaraguan Morse code stations, with fading causing the Morse characters to be unreadable. There is not enough evidence to decide what the source was.
Credibility Uncertain
71
Identifier 41114IA
Z Time/Date 1114-1115 July 4
Local Time/Date 2344-2345 July 3
Gardner Time/Date 0014-0014 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content General call (CQ) Morse code signals heard almost on top of the carrier that Itasca has been hearing. The signal is very weak and unreadable in severe atmospheric noise.
Source RADREST.PDF, p. 155
Probability 0.69
Qual Factors Neither Earhart nor Noonan was proficient in Morse code. Itasca evidently was hearing two Nicaraguan stations, as discussed earlier in this catalog.
Credibility Not credible
72
Identifier 41122IA
Z Time/Date 1122-1124 July 4
Local Time/Date 2352-2354 July 3
Gardner Time/Date 0022-0024 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Someone was sending with a high-speed Morse code key. The words “unlimited” and “clear” were understood, but the remainder was unreadable.
Source RADREST.PDF, p. 155
Probability 0.68
Qual Factors Neither Earhart nor Noonan was proficient in Morse, and certainly could not transmit Morse code at high speed. The most likely source was a Nicaraguan station.
Credibility Not credible.
73
Identifier 41127IA
Z Time/Date 1127-1137 July 4
Local Time/Date 2357-0007 July 3 - 4
Gardner Time/Date 0027-0037 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca still hears a continuous carrier on 3105 kHz.
Source RADREST.PDF, p. 155
Probability 0.68
Qual Factors It was not plausible for Earhart to key her transmitter for such a long period. Itasca most likely was hearing the carrier of one of the Nicaraguan stations.
Credibility Not credible.
74
Identifier 41200CV
Z Time/Date 1200 July 4
Local Time/Date 0400 July 4
Gardner Time/Date 0100 July 4
Agency/Person COMFRANDIV
Location San Francisco
Freq (kHz) 6210
Content COMFRANDIV told Itasca that a special monitoring station set up to listen for Earhart signals heard a strong carrier, but not voice, on 6210 kHz for about 15 minutes. The signal appeared to be coming from a westerly direction.
Source MSG8.PDF, p. 352
Probability 0.14
Qual Factors 6210 kHz is the second harmonic of Earhart’s night frequency, 3105 kHz. But it is not plausible that Earhart would key her transmitter for such a long period. COMFRANDIV said that the special monitor station (MSG9.PDF, p. 394) used “diamond beam” antennas aimed at Honolulu. “Diamond beam” is a generic term for a rhombic antenna, which has a diamond-shaped physical geometry. Such antennas were used by press services for communication with remote sites such as Hawaii. The COMFRANDIV monitor site was at the Press Wireless company facility, which used rhombic antennas for communication with Honolulu. A rhombic antenna is very sensitive to signals arriving from the direction of its main axis, but also has sidelobes that can receive signals from directions perpendicular to the antenna’s main axis. In the case of the Press Wireless antennas, the sidelobes were pointed along the west coast, hence this signal could have come from west coast aircraft. There is not enough evidence to conclude that Earhart was the source.
Credibility Uncertain
75
Identifier 41153CV
Z Time/Date 1153-1353 July 4
Local Time/Date 0353-0553 PST July 4
Gardner Time/Date 0053-0253 July 4
Agency/Person COMFRANDIV
Location San Francisco
Freq (kHz) 3105 and 6210
Content COMFRANDIV told Itasca that for the past two hours, no signals were heard on 3105 kHz, but a weak carrier signal of unspecified duration, with no modulation, was heard on 6210 kHz, apparently originating west of San Francisco, and that the signal disappeared at 0150 GCT, i.e. Z time.
Source MSG8.PDF, p. 352
Probability 0.07
Qual Factors The timing of the 6210 kHz signal is vague. The start time is not given, and the “0150 GCT” time is outside the period covered by this report, and may be a garble. It is possible that the signal was from a west coast source, and was received in sidelobes of the rhombic (“diamond beam”) antennas at the COMFRANDIV special monitoring site. There is not enough evidence to conclude that Earhart was the source.
Credibility Uncertain.
76
Identifier 41200CC
Z Time/Date 1200 July 4
Local Time/Date 0130 HST July 4
Gardner Time/Date 0100 July 4
Agency/Person Coast Guard Commander, Hawaiian Section (COMHAWSEC)
Location Honolulu
Freq (kHz) 3105
Content COMHAWSEC informed Itasca of hearing a carrier signal on “about 3105 kHz,” lasting one minute, with speech identified as a man’s voice. No details given as to what was said.
Source MSG8.PDF, p. 354
Probability 0.0021 (Gardner); 0.0003 (west coast)
Qual Factors Earhart’s transmitter was the only plausible source of voice on or near 3105 kHz in the central Pacific. If this signal had originated on the west coast, it almost certainly would have been heard by at least one of the FAA stations there, required to listen on 3105 kHz.
Credibility Credible
77
Identifier 41215WD
Z Time/Date 1215 July 4
Local Time/Date 1215Z July 4
Gardner Time/Date 0115 July 4
Agency/Person Pan American Airways radio direction finding station
Location Wake Island
Freq (kHz) 3105
Content Wake heard an intermittent male voice, of “rather wobbly characteristics.” Atmospheric noise prevented understanding what was said. At 1210Z, Wake heard several unreadable voice signals near 3105 kHz, in noise.
Source Memorandum from Operator in Charge, Wake, to Division Superintendent, Communications, Alameda dated July 10, 1937.
Probability 0.000079 (Gardner); less than 1 chance in a quadrillion for a signal from the west coast.
Qual Factors Earhart’s transmitter was the only plausible source of voice signals in the central Pacific. Given Wake’s distance from the U.S. west coast, approximately 4,000 nautical miles, it is highly doubtful that this signal was from a west coast aircraft. Itasca was not transmitting at this time.
Credibility Credible
78
Identifier 41200DN
Z Time/Date 1200-1230 July 4
Local Time/Date 0130-0200 HST July 4
Gardner Time/Date 0100-0130 July 4
Agency/Person Mr. Donaldson
Location Wahiawa, Oahu, Hawaii
Freq (kHz) 3105 (assumed)
Content The Navy radio station at Wailupe received a report from a Mr. Donaldson of Wahiawa, relayed by the Mutual Wireless Company office in Wahiawa. Donaldson described several signals heard on his Zenith shortwave receiver, on an unspecified frequency, at unspecified specified times between 1200Z and 1230Z. He said he heard a man’s voice say “31.05,” “31.07,” and “KHAQQ,” and then “62.05,” and “help.”
Source MSG8.PDF, p. 355; Finding Amelia, p. 138
Probability 0.0021 on 3105 kHz, and 0.18 on 6210 kHz
Qual Factors Donaldson did not say what model receiver he used. He gave the receiver dial index scale settings where he heard signals, but they are meaningless without knowing the receiver model, since Zenith did not use a common dial design for all models. It is possible that he heard Fred Noonan, Earhart’s navigator, saying “3105,” which was garbled to “31.05” during the relay, but there was no plausible reason for Noonan to say “3107” since Earhart’s transmitter could not operate on that frequency. The “62.05” that Donaldson reported could have been a garble of Earhart’s day frequency, 6210 kHz. KHAQQ was Earhart’s call sign, and the word “help” was plausible in the circumstances. However, all this information was available from public sources, and Donaldson’s report could be a hoax. Although it is possible that Donaldson heard the same signals heard by COMHAWSEC (Identifier 41110PU above) and Wake Island Identifier 41114IA above), there is no evidence corroborating Donaldson’s claim.
Credibility Uncertain
79
Identifier 41330MC
Z Time/Date 1330 July 4
Local Time/Date 0530 PST July 4
Gardner Time/Date 0230 July 4
Agency/Person Walter McMenamy, Karl Pierson and “Bo” McKneely
Location Los Angeles
Freq (kHz) 6210
Content Pearson said “We heard nothing decipherable during the night, and at 5:30 (8:30 am Chicago time) the carrier waive faded out. Just before that we heard a voice definitely that of a woman and sounding like the voice I had heard more clearly yesterday.” “McMenamy has said he was familiar with Miss Earhart’s radio voice, having heard it many times, and that the words of distress, spoken so calmly Saturday morning, were those of the aviatrix, now down in the South Pacific.” “‘Bo’ McKneely, Miss Earhart’s mechanic at Burbank, CA also heard the call on McMenamy’s powerful set. He called Paul Mantz, Miss Earhart’s technical adviser, reporting that the radio call was fast, ‘too fast to distinguish clearly.’ He said after the call letters something else was sent, ‘probably a position.’”
Source Chicago Herald and Examiner, Monday, July 5, 1937.
Probability n/a
Qual Factors Pearson’s associate Walter McMenamy later confessed this was a hoax. (Audio tape in TIGHAR archives)
Credibility Not credible
80
Identifier 41437PY
Z Time/Date 1437 July 4
Local Time/Date 1437 Z July 4
Gardner Time/Date 0337 July 4
Agency/Person Pan American Airways radio direction finding station
Location Midway Island
Freq (kHz) 3105
Content A very weak wobbly signal was heard, which sounded like voice but was too weak to identify. Wake Island also heard this same signal, but Mokapu did not hear it.
Source Memorandum from Operator in Charge, Midway, to Division Superintendent. Communications, Alameda dated July 10, 1937.
Probability 0.00037
Qual Factors Earhart’s transmitter was the only plausible source of voice signals on 3105 kHz in the central Pacific, but also could have been a west coast aircraft. Itasca did not transmit to Earhart until 2100Z this day. There is insufficient evidence to decide if Earhart was the source.
Credibility Uncertain
81
Identifier 41500RH
Z Time/Date 1500-1525 (approx) July 4
Local Time/Date 0800-0825 MST July 4
Gardner Time/Date 0400-0425 (approx) July 4
Agency/Person Dana Randolph
Location Rock Springs, Wyoming
Freq (kHz) 15525
Content According to the local newspaper, Randolph heard a woman say “This is Amelia Earhart. Ship is on a reef south of the equator. Station KH9QQ” at about 0800 MST. The woman then began to give her location, but the signal faded out before it was given. This sequence was repeated an unknown number of times during a 25 minute period.
Source “First Radio Contact with Miss Earhart Made by Rock Springs boy,” Rock Springs Rocket, July 6-7, 1937, p.1; Finding Amelia, p. 142; MSG8.PDF, p. 368; and MSG9.PDF, p. 372.
Probability 0.016
Qual Factors A local Department of Commerce radio operator investigated and verified Randolph’s report, and found that the call sign heard was KHAQQ, and that the signal frequency was “near 16000” kHz, which is close to 15525 kHz, the 5th harmonic of 3105 kHz. It was plausible for Randolph to be tuning there, since 15525 kHz was near a shortwave broadcast band. The investigator also found that the signal included a statement – not reported by the newspaper – that the plane was “on a reef southeast of Howland Island.” The possibility of a hoax can be ruled out, given the investigation and the fact that the newspaper was published every other day, hence printed news of post-loss signals had not yet reached Rock Springs.
Credibility Credible
82
Identifier 41500CB
Z Time/Date 1500 and unspecified subsequent times, July 4
Local Time/Date 1100 Eastern Daylight Time, July 4
Gardner Time/Date 0400, July 4
Agency/Person Mrs. Ernest Crabb
Location Toronto, Canada
Freq (kHz) 18630 kHz
Content Mrs. Crabb said she heard fragments of a conversation between a woman and a man she believed to be Amelia Earhart and Fred Noonan, on her 20-tube radio on Sunday July 4. She said she also heard a few sentences in what seemed to be Japanese, breaking in.
Source Toronto Daily Star, July 5, 1937, and Toronto Daily Star, July 6, 1937.
Probability 0.009
Qual Factors 18630 kHz is the 6th harmonic of 3105 kHz. This reception was simultaneous with the signal on 15,525 kHz, the 5th harmonic of 3105 kHz, heard by Dana Randolph in Rock Springs, Wyoming. There were two 20-tube home radios with shortwave capability in 1937: the Midwest Radio Co. Model 20-38, which had a shortwave band covering 10 MHz to 20 MHz, and the Philco model 37-690X, which had a shortwave band covering 11.5 MHz to 18.2 MHz. There was a 50,000 watt Japanese station – JZL in Tokyo – at 17,785 kHz. This could explain why Mrs. Crabb was tuning in that part of the band, and why occasional Japanese sentences could be heard on 18,630 kHz. Home radios of the day had poor selectivity on shortwave bands, and random changes in the propagation path could allow the JZL signal strength at Toronto to rise enough to overcome the receiver selectivity and be heard together with a signal from Earhart’s 50-watt transmitter at Gardner.
Credibility Credible
83
Identifier 41512PY
Z Time/Date 1512 July 4
Local Time/Date 1512 GCT July 4
Gardner Time/Date 0412 July 4
Agency/Person Pan American Airways Radio direction finding station
Location Midway Island
Freq (kHz) 3105
Content A faint broad signal, apparently voice, was heard but was far too weak to take a bearing. Wake Island did not hear this signal. Mokapu reported taking a bearing of approximately 175 degrees true. (Note: The bearing of Gardner from Mokapu is 213 degrees true.)
Source Memorandum from Operator in Charge, Midway, to Division Superintendent. Communications, Alameda dated July 10, 1937.
Probability 0.00037 (Gardner); less than 1 chance in a quadrillion for a signal from the west coast.
Qual Factors This signal was heard during the period when voice signals were heard at Rock Springs and Toronto. Earhart’s transmitter was the only plausible source of voice signals in the central Pacific. The possibility of a west coast aircraft source can be ruled out because the bearing of a west coast source from Mokapu ranged from 038° (Seattle) to 065° (San Diego). The difference between 213° and the reported bearing of 175° is plausible given the weak signal and probable skywave directional skewing.
Credibility Credible
84
Identifier 41523PU
Z Time/Date 1523-1530 July 4
Local Time/Date 1523-1530 Z July 4
Gardner Time/Date 0423-0430 July 4
Agency/Person Pan American Airways Radio direction finding station
Location Mokapu, Oahu
Freq (kHz) 3105
Content Mokapu heard weak carrier signals on 3105 kHz and got a bearing of 213°, that could be in error by plus or minus 10° due to signal direction shifting.
Source MSG8.PDF, p. 357. and Memorandum from Pan Am Section Supervisor, Communications, Honolulu to Division Superintendent, Communications, Alameda dated July 10, 1937.
Probability 0.009
Qual Factors The signals were heard during the period when credible Earhart signals were heard at Rock Springs and Toronto. The bearing of Gardner from Mokapu is 213°. Shifting, or swinging, of a direction finder bearing was a plausible result of weak-signal multipath interference due to ionospheric propagation anomalies.
Credibility Credible
85
Identifier 41553PY
Z Time/Date 1553 July 4
Local Time/Date 1553 GCT July 4
Gardner Time/Date 0453 July 4
Agency/Person Pan American Airways Radio direction finding station
Location Midway Island
Freq (kHz) 3105
Content A weak signal, apparently the same signal heard at 1512Z was heard but was far too weak to identify.
Source Memorandum from Operator in Charge, Midway, to Division Superintendent. Communications, Alameda dated July 10, 1937.
Probability 0.0066
Qual Factors The signals were heard shortly after the credible Earhart signals heard at Rock Springs and Toronto.
Credibility Credible.
86
Identifier 42100IA
Z Time/Date 2100 July 4
Local Time/Date 0930 July 4
Gardner Time/Date 1000 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca called Earhart in voice, with a long count, requesting her to respond.
Source RADREST.PDF, p. 162
Probability n/a
Qual Factors n/a
Credibility n/a
87
Identifier 42130IA
Z Time/Date 2130 July 4
Local Time/Date 1000 July 4
Gardner Time/Date 1030 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca called Earhart in voice, with a long count, requesting her to respond.
Source RADREST.PDF, p. 163
Probability n/a
Qual Factors n/a
Credibility n/a
88
Identifier 42200IA
Z Time/Date 2200 July 4
Local Time/Date 1030 July 4
Gardner Time/Date 1100 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca called Earhart in voice, with a long count, requesting her to respond.
Source RADREST.PDF, p. 164
Probability n/a
Qual Factors n/a
Credibility n/a
89
Identifier 42230IA
Z Time/Date 2230 July 4
Local Time/Date 1100 July 4
Gardner Time/Date 1130 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca called Earhart in voice, with a long count, requesting her to respond.
Source RADREST.PDF, p. 164
Probability n/a
Qual Factors n/a
Credibility n/a
90
Identifier 42300IA
Z Time/Date 2300 July 4
Local Time/Date 1130 July 4
Gardner Time/Date 1200 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca called Earhart in voice, with a long count, requesting her to respond.
Source RADREST.PDF, p. 165
Probability n/a
Qual Factors n/a
Credibility n/a
91
Identifier 42330IA
Z Time/Date 2330 July 4
Local Time/Date 1200 July 4
Gardner Time/Date 1230 July 4
Agency/Person Itasca
Location Central Pacific
Freq (kHz) 3105
Content Itasca called Earhart in voice, with a long count, requesting her to respond.
Source RADREST.PDF, p. 165
Probability n/a
Qual Factors n/a
Credibility n/a
Background   |   Messages July 3, 1 – 47   |   Messages July 4, 48 – 91
Messages July 5, 92 – 144   |   Messages July 6 – 10, 145–182
Research Papers Earhart Project Home Page
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