Earhart’s Final Flight

Earhart departed from Lae, New Guinea at 00:00 GMT with 1,100 US gallons of fuel on-board her Electra.

The planned true airspeed was 130knots and the distance to Howland flying a direct course was 2,222 nautical miles. Therefore with no headwinds the minimum flight time would have been 17:05 hours. Headwinds were forecast meaning that the original estimated time of arrival was 18:00 GMT, approximately 15 minutes after sunrise at Howland.

howland

Times had been prearranged for radio transmissions throughout the flight between Earhart and a number of other stations. Initially she would remain in contact with Lae, transmitting at 18 minutes past the hour GMT.

These are Earhart’s messages recorded by the Lae personnel.

  • 0418: “Height 7000 feet, speed 140 knots” then some remark concerning “Lae” then “everything OK.”
  • 0519: “Height 10,000 feet position 150.7 E 7.3 S cumulus clouds everything OK.”
  • 0718: “Position 4.33 S 159.7E height 8000 feet over cumulus clouds wind 23 knots.”

The position given at 0519 must be in error as it places Earhart only 186 nautical miles away from Lae after over 5 hours of flight. It is likely a transposition error and should read 157° 00′ E 7° 03′ S which would place Earhart over Choiseul Island 597 nautical miles from Lae. The second position report gives coordinates in the vicinity of Nukumanu Island. The position is 737 nautical miles from Lae, or 793 nautical miles away flying via the 05:19 position.

fina-flight3

The USS Ontario was stationed between Lae and Howland to aid Earhart. The problem was that communication between the Ontario and the Electra never occurred. Ontario was to transmit ‘N’s by Morse on 400kcs on request. Herein lies the problem. Ontario didn’t have any high frequency equipment and therefore would not be able to hear Earhart’s request for the signals.

At 10:30 GMT Nauru heard Earhart state “Ship in sight ahead”. The only ships known to be in the general vicinity of Earhart’s course were the USS Ontario and the MV Myrtlebank. The position of Ontario was 2°59.02′S, 165°23.20′E, 387 nm from the 07:18 position. The position of Myrtlebank is not known precisely but was slightly to the North and East of Ontario.

Stationed off Howland was the USCGC Itasca. The cutter was to communicate with Earhart via radio and to provide signals for her to ‘home in’ on using her radio direction finder. The ship was also to send up black smoke from the funnel as a visual aid. Prior to the flight, arrangements had been made regarding inflight radio communication between Earhart and Itasca.

These are the radio messages heard by Itasca in GCT translated into common English with some discussion.

Itasca had more than one radio transcript. The messages here are taken from the transcript for Itasca’s radio station 2 which was responsible for all Earhart communications:

  • 1415: “Heard Earhart plane / but unreadable thru static (Heard Earhart’s plane but unreadable through static)
  • 1515: “Earhart heard fone/will lissen on hour and half on 3105-sez she (Heard Earhart speaking. She says that she will listen on the hour and half hour on 3105 kilocycles.)
  • 1623: “Heard Earhart (Part Cldy)”; (Heard Earhart. She says it’s partly cloudy)
  • 1742: “Wants bearing on 3105 KCS on hour. Will whistle in mic. About two hundred miles out appx. Whistling now.” (Earhart states that she wants Itasca to take a bearing on her and to report the bearing on the hour on 3105 kilocycles. She states that she will whistle in the microphone and that she is about 200 miles away. She then whistles.)
  • 1812: “Pse [please] take bearing on us and report in half hour–I will make noise [sic] in mic – abt 100 miles out”; (Earhart again asks for Itasca to take a bearing on her and report on the half hour. She will make noise in the microphone. There is some disagreement over this message. It appears that she is saying that she is 100 miles out. This would give an impossible ground speed of 200 knots. Either some fix was achieved which updated their position or Earhart is actually saying that she will whistle WHEN she is 100 miles out.)
  • 1912: “KHAQQ clng Itasca we must on you but cannot see u but gas is running low been unable to reach you by radio we are flying at a 1000 feet.” (KHAQQ is Earhart’s call sign. She says that she must be close to Itasca and Howland but she is unable to see them. She states that gas is running low and that she is flying at 1000ft. Another Itasca operator recorded that Earhart stated she only had half an hour of fuel remaining.)
  • 1928: “KHAQQ clng Itasca we are circling but cannot hr u GA on 7500 wid a lng count either nw or on the skd time on 1/2 hour (Earhart says that she is circling but is unable to hear Itasca. She asks them to transmit signals on 7500 kilocycles at that moment or at half past the hour.)
  • 1930: “KHAQQ clng Itasca we recd ur sigs but unable to get a minimum pse take bearing on us and ans 3105 wid voice / NRUI de KHAQQ lng dashes on 3105 (Earhart acknowledges that she heard the Itasca’s signals but was unable to take a bearing from them. She asks for them to take a bearing on her and respond with voice on 3105 kilocycles. She then proceeds to send dashes by voice.)
  • 2013: “KHAQQ to Itasca we are on the line 157 337 wl rept msg we will rept this on 6210 KCS wait, [(3105/A3 S5 (?/KHAQQ xmission we are running on N ES S line) (Earhart states that she is on the sun line of position 157-337. She states that she will repeat the message on 6210 kilocycles. She comes back on saying that she is running North and South on the line. It is apparent that this message is very messy. It seems that Earhart came back on air unexpectedly to add that she was running North and South, which is why the operator had to try and fit that latter part of the message into the transcript. See below an excerpt from the original log to indicate this.

Two way radio contact was never properly obtained between Earhart and Itasca. The 19:30 radio message is the only one that indicates that Earhart heard anything at all from Itasca. It has been speculated that perhaps something was wrong with Earhart’s radio equipment. This could not be proved either way, however, there is a lot of evidence to show that even with fully functioning equipment, the seeds of disaster had been sown with poor organisation.

Radio Direction Finding: There were 3 direction finders in play during the final flight – one on Earhart’s Electra, one on Itasca and one on Howland. All three failed to provide a bearing. Earhart requested Itasca transmit the letter “A” on 7500 kilocycles for her to take a bearing from. It is therefore clear to see why Earhart could not get a minimum on Itasca’s signals at 19:30 since her direction finder was only designed to take bearings up to 1430 kilocycles. 7500 was much too high. The direction finder on Itasca could not take bearings on frequencies higher than 550 kilocycles. All messages heard from Earhart were on 3105 kilocycles – again too high to get a minimum. A high frequency direction finder capable of taking bearings up to 3105 kilocycles was placed on Howland Island, however the batteries were too run down by the time Earhart was in the vicinity that a bearing was impossible.

On top of the RDF failures, there are further apparent failures in communication:

  • Itasca did not seem to know that Earhart could not understand Morse. Most of their communications to the Electra were by key despite her specific instructions to communicate by voice.
  • Itasca seemed to be confused by time zones. Earhart had specified that GCT was to be used, however it seems that Itasca was working from their own time-zone of GCT +11.5 meaning that they didn’t respond to Earhart’s requests appropriately. For example at 1742GCT Earhart requests a bearing on the hour – ie. in 18 minutes time. It is 0612 Itasca time and to them it seems that Earhart is requesting a bearing in 48 minutes. If she was listening at 1800 GCT on 3105 kilocycles for Itasca she would have heard nothing as they were transmitting Morse on 7500 kilocycles at this time.
  • Earhart did not stay on air long enough for Itasca to even try and get a minimum from her signals.
  • Itasca was not always doing what Earhart was probably expecting them to be doing. Especially as the flight neared the tense conclusion Itasca increasingly was broadcasting on frequencies that Earhart may not have been listening to, at times Earhart may not have been listening at, and they even potentially blocked out further Earhart transmissions by transmitting over her during her transmission times.

final-flight2

After the 20:13 message, Earhart was never heard from again. Itasca began the search for her at 10:40, beginning the largest US search in history up to that point for a missing person. On July 18th the US Navy gave up their search. No sign of Earhart, Noonan or the Electra was found.