The World Flight, Second Attempt:

The Final Flight

Part 1: Lae to Midpoint

Introduction

For purposes of analysis, the Earhart flight can be divided into four basic segments. The first segment covers the time from take-off at 0000 GMT on July 2 from Lae to the time of the last radio transmission at 0718 GMT heard by Harry Balfour, the Lae radio operator. The second segment covers the time period from 0718 GMT until the first credible reception of radio heard by the radiomen of Itasca, at 1415 GMT. This segment includes the sighting of a ship near Nauru, as reported by the Nauru radio station. The third segment covers the period from 1415 GMT until 1930 GMT, which includes the last transmission of Earhart useful for locating her plane. The final segment covers the time period after 1930 GMT until the ultimate time when Earhart’s plane returned to Earth.

There are a variety of contemporaneous documents that help determine Earhart’s flight parameters:

  • Eric Chater’s descriptions of messages heard by Harry Balfour, the wireless operator at Lae, New Guinea.1
  • James Collopy’s descriptions of these same messages.2
  • A description of the report of the Commander of the Lexington Group of a message heard by the radio station at Nauru Island.3
  • A radio message from Nauru the evening of the disappearance.4
  • Three separate, original, and raw radio transcripts by the Itasca and Howland personnel.5
  • A summary report by the Commander of the Itasca.6
  • A summary report by Richard Black in the 10th Equatorial Cruise Report. 7
  • A summary report by US Army Lt. Daniel A Cooper.8
  • An account in a letter by Captain Irving Johnson of the yacht Yankee describing a witness report of the aircraft’s passage over the island of Tabiteuea in the Gilberts.9

While there appears to be a lot of documentation, it is insufficient to determine with any certainty exactly what happened to Earhart and Noonan.

Lae to 0718 GMT

The radio operator at Lae, Harry Balfour, made no written record of what he heard from the Earhart flight and the recollections he wrote down in 1969 disagree with the Chater and Collopy documents, written in July, 1937. Not only do Chater and Collopy both contradict Balfour, they disagree with each other about the content of the messages received from Earhart.

Both Chater and Collopy agree that the aircraft departed Lae, New Guinea at 0000 GMT, or 10AM local time.

Chater states that local interference prevented signals from the plane to be heard at Lae until 0418 GMT, but that a call had been made to the plane at 18 minutes past each hour to pass weather information.

Chater states that at 0418 GMT, the Lae radio operator heard on 6210 kHz: “Height 7000 feet, speed 140 knots” then some remark concerning “Lae” then “everything OK.” Chater further states that the plane was called and asked to repeat its position but got no response. Collopy makes no mention of this message. At 4 hours and 18 minutes into the flight, the 7000 foot altitude makes sense, but the reported speed of 140 knots seems odd. At that altitude, and in a still heavily-overloaded airplane, we might expect Earhart’s airspeed indicator (which read in mph, not knots) to show a figure slightly less than her normal cruising speed of 150 mph (130 knots). So, if she had simply said “speed 140” the report would make sense. On the other hand, if the expression was truly in knots, then it must have been calculated by navigational landmarks or sun-lines by Noonan, and indicates true speed over the ground. If this was the case, then the airplane would have a 10 knot tailwind, or be operating at an uneconomical power setting. It would seem more reasonable to attribute the discrepancy to a knots vs. mph misunderstanding at Lae.

At 0519 GMT, Earhart again broadcast a message on 6210 kHz. Chater reports: “Height 10000 feet position 150.7 E 7.3 S cumulus clouds everything OK.” Collopy states: “At about 3 PM local time a message came through to the effect that they were at 10,000 feet but were going to reduce altitude because of thick banks of cumulus clouds.” This is a puzzling message. The coordinates related by Chater place the airplane well south of the intended rout and, although the flight had been en route for 5 hours and 19 minutes, the position reported is only 186 nm from Lae, giving the airplane a ridiculous ground speed of 37 knots. The reported 10,000 feet of altitude is higher than the 8,000 feet recommended by Kelly Johnson for best fuel economy on this portion of the flight. None of this message makes sense in the light of the reported comment “everything OK,” and we must conclude that either the message or its transcription was inaccurate.

At 0718 GMT, the last and final message was received by Lae personnel from Earhart. Chater reports: “Position 4.33 S 159.7E height 8000 feet over cumulus clouds wind 23 knots.” Collopy states: “The next and last message was to the effect that they were at 7,000 feet and making 150 knots, this message was received at approx. 5 PM local time.” Again, there are discrepancies between the two reports. The position provided places the plane in the vicinity of the Nukumanu Islands (4.3°S, 159.30°E). No time was provided for when this position was obtained. This position is 735 nm from Lae and is right on course for the great circle route to Howland, and seems suspiciously to be a dead reckoning position. First, there were no good maps of the Nukumanu Islands at small scales in 1937; secondly, Noonan had a habit of marking half-hourly projections along the intended flight path and was known to relay these positions to Earhart (see discussion on the Oakland to Honolulu segment previously); navigation during daylight hours was limited to lines of position shot from the sun and any visual landmarks; and the double digit accuracy of the latitude position seems unusual but it may simply indicate 1/3 of a degree. The reported altitude of the plane (8000 feet) is consistent with fuel economy plans, but Collopy’s 7000 foot altitude and speed makes more sense if he was referring to the message received 3 hours earlier. The wind speed of 23 knots seems consistent with the Nauru observation of 24 mph (19 knots) at 7500 feet, but Earhart did not give an indication of wind direction. Finally, we note that the plane is above the clouds just as dusk is approaching, allowing Noonan to obtain celestial fixes.

At this time, according to Chater, Earhart changed radio frequencies from 6210 kHz, her daytime frequency, to 3105 kHz, the nominal nighttime frequency. Chater reports that the signals up to this time were strong, and the plane was called not to change frequencies. No replies were heard or other messages during the next three hours as both frequencies were scanned by Balfour. Chater's report clearly documents that at no time did Earhart and Lae establish two-way communication, nor is there any evidence that Earhart heard any of Lae's broadcasts to her.

Meanwhile, the Itasca radiomen had been running a radio watch on 6210, 3105, and 500 kHz, listening for Earhart since 1131 GMT, July 1. At that time, the Itasca did not know when Earhart was to take off, so they kept a continuous watch from that time forward. At 0415 GMT on July 2, Itasca communicated with Radio Tutuila, who stated that Radio Tutuila still had not heard anything via Suva as to whether Earhart had left Lae.10 At 0542 GMT, Itasca intercepted a radio communication from Radio Tutuila to Ontario saying that Radio Suva reports that Earhart took off at 9:30 AM.11 At 0601 GMT, Itasca received a telegram from the USCG office in San Francisco, stating that Earhart left Lae at noon, Lae time. At 0630, the second radio watch specifically for Earhart was established and began to send weather reports on 7500 kHz; these transcripts are hereafter referred to as Itasca2 radio transcripts, if smoothed, and Bellarts for the original raw transcripts.12 At 0725 GMT, Itasca got a radio message from Vacuum Oil in Lae that Earhart took off at 10AM local time, and her expected flying time was 18 hours.13 At 0726 GMT, Itasca reports hearing a faint signal on 3105 kHz from Earhart, strength 1, voice signal, but unreadable.14 This was probably not Earhart, as it is not at her scheduled broadcast time.

There is little information regarding weather conditions during this first segment of Earhart’s flight. The forecast from the Fleet Air Base in Honolulu estimated that the winds around Lae were 25 knots ESE from Lae to where the Ontario was situated (approx. 3°S, 165.6°E). 15 Nauru, located at 32′S, 166°55′E, had reported at 2130 GMT on July 1 that it was experiencing 14 mph (12.1 knots) winds from the East at 2000 feet, 12 mph (10.4 knots) from the East at 4000 feet, and 24 mph (20.9 knots) from the East at 7500 feet.16 The Ontario during this time experienced Force 3 winds (7-10 knots) from 0000 to 0200 GMT, from NExE (56.25°), shifting to Easterly at 0200 GMT. At 0300 GMT, Ontario experienced easterly winds at force 2 (4-6 knots), then from 0400 to 0900 GMT, experienced easterly winds at force 3.17 Generally below the meteorological equator, located at this time of the year at 5°N, winds shift northerly with altitude from the sea by about 10 degrees to the north, and experience a 30% increase in speed.

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