On July 2, 1937, American aviation pioneer Amelia Earhart was attempting to circumnavigate the globe in a modified twin-engine Lockheed Electra 10E when she — and her navigator, Fred Noonan — mysteriously disappeared in the middle of the Pacific Ocean near Howland Island. The mystery of what happened to her has captivated the world ever since. One group, TIGHAR, (The International Group for Historic Aircraft Recovery) has made solving that mystery a major focus for the past few decades. Over the last 25 years, the organization has assembled an enormous amount of circumstantial evidence suggesting Earhart did not crash into the ocean as was assumed, but may have landed at Nikumaroro (known then as Gardener Island).
The group’s latest findings concern a skeleton found on Nikumaroro in 1940 by the British. At the time, the British doctor who examined the bones concluded they belonged to a male (though this could have also been Earhart’s navigator, Fred Noonan). The skeleton was lost in WW2, but the examining doctor’s notes were found in 1998. Modern analysis of the data demonstrated they were consistent with a woman of Earhart’s height and anatomy, but nothing more than that.
During a recent re-examination of the data, Dr. Richard Jantz (who examined the notes in 1998) noticed something interesting. The radius bone on the 1940 skeleton was 24.5cm long, while the humerus was reportedly 32.4cm long. This corresponds to a ratio of 0.756, while the average radius-to-humerus ratio for a mid-20th century middle-aged human female was 0.73.
TIGHAR called upon forensic image analyst Jeff Glickman to examine period photographs of Earhart, like the one shown above, to attempt to determine how long her arm bones were. Working with Dr. Jantz, Glickman determined that the radius-to-humerus ratio for Earhart was 0.76 — nearly identical to the 0.756 recorded by the British in 1940.
In and of itself, this is scarcely evidence. The radius-to-humerus ratio for men and women is nearly identical, and the standard deviation for both sexes is large enough to overlap the 1940 skeleton’s 0.756 ratio, even if the skeleton did belong to Earhart. But — and this is critical — these skeleton measurements are the merest tip of the iceberg as far as the evidence TIGHAR has encountered. Since 1989, TIGHAR has been compiling data, evaluating evidence, and assembling information on where Earhart’s Lockheed Electra 10E might have gone down, and where the wreck is now. There are two things you need to know before diving into this story:
1) I have chosen some of the highlights and most interesting details, not to cherry pick the evidence for the Nikumaroro landing theory, but because TIGHAR has produced several hundred PDFs of evidence, analysis, historical documents, and records. I highly recommend that anyone who finds this topic interesting dive into that body of research. A shorter version for those without several hours to spare is also available.
2) All of the evidence we’re going to discuss is circumstantial. The strength of the argument is that there is an absolutely mind-boggling amount of circumstantial evidence: multiple reports from settlers and navy personnel of recent habitation, including one such report from the navy pilot who overflew Gardner Island in the week following Earhart’s crash. A body recovered from the island (along with American shoes) in the 1930s, before being lost in World War 2. Photographs of what appears to be airplane wreckage. Villagers and one-time settlers who report seeing and even using bits of metal and material that would match said airplane wreckage. The discovery of a water catchment system in 1944 that could’ve been built using materials carried aboard Earhart’s Electra.
After a review of the evidence TIGHAR has found to date, I personally find the Nikumaroro hypothesis extremely credible. But readers should be aware that whether the Lockheed Electra 10E possessed sufficient fuel to reach the island is a matter of debate and depends, to some extent, on how you read the radio transmissions the Itasca picked up.
Amelia Earhart and navigator Fred Noonan took off from Lae, New Guinea on July 2, 1937. They were flying a specially outfitted Lockheed Electra 10E. But they had made several changes to the plane’s equipment, particularly its antenna layouts and structure, that may have critically harmed communication between the plane and its ship tender, the United States Coast Guard Cutter Itasca. The Itasca was standing by at Howland Island to signal the Electra and guide it in.
Unfortunately, due to the aforementioned communications problems, the Lockheed and the cutter never made contact. While the ship could hear Earhart, it could not respond to her transmissions on the same frequency. Earhart’s last transmission stated the following:
“We are running on line 157-337… We are running on line.”
What this means is fairly simple: Noonan, as navigator, had taken the aircraft’s line of position relative to the sun’s location as it rose. Overcast conditions had prevented him from using celestial navigation overnight, but using a single body for a line position only told Earhart part of where she was. The slideshow below contains additional information about the Electra, its position, possible damage to the radio antenna that would have compounded her problems communicating with the Itasca, and data on what being “on line” meant.
In theory, she could’ve been anywhere along that course, from directly on top of Howland Island or Baker to far off-course in either direction. No further transmissions were received by the Itasca and prevailing wisdom for decades has been that Earhart’s Electra ran out of fuel and landed in the ocean.
TIGHAR has compiled evidence that illustrates otherwise, and backed it up with formidable analysis. Let’s consider some of the highlights.
July, 1937: A 15-year old girl named Betty is listening to her family’s radio, tuned to “short wave” frequencies. Her father had run a 60-foot antenna, and the set was capable of picking up transmissions from all over the world. She hears — or believes she hears — the words “This is Amelia Earhart.”
This was scarcely uncommon at the time. But what separates Betty from a number of other witnesses is that she kept a notebook of everything she heard and when she heard it. More than sixty years later, TIGHAR researchers sat down with her to determine whether or not her claims were possible. At first glance, this might seem farcical. Surface craft and radio stations within a few hundred miles of Gardner/Nikumaroro could only pick up rough triangulations and estimates on Earhart’s transmissions. How could a teenager be hearing her in St. Petersburg, Florida?
The answer lies in the hardware of the day. Earhart was broadcasting on a Western Electric 13C radio and broadcasting on 3105, 6210, and 500 Kilocycles. Her radio, however, lacked any form of harmonic suppression equipment — meaning that when she broadcast on these frequencies, she was simultaneously and inadvertently broadcasting at much higher frequencies as well. Furthermore, Earhart’s aircraft antenna had been modified in a manner that inadvertently boosted the harmonic signal emanating from the aircraft.
All of this would be moot, however, if the radio set Betty’s family owned was incapable of receiving the harmonic signals Earhart would have been broadcasting. That radio — a Zenith 1000Z Stratosphere — was one of the most capable and powerful consumer sets available on the market from 1935-1938. Not only was that particular model capable of receiving a harmonic frequency of Earhart’s broadcasts, but the nature of what Betty heard — faint, scratchy, intermittent audio — matches the statistical probability of what she’d have been likely to hear. At the most likely frequencies, the signal-to-noise (SNR) ratio was only barely high enough to permit intermittent contact.
But there’s another side to Betty’s notebook — the question of what she heard. And this is where the story gets a little chilling. The slideshow below contains multiple pages from Betty’s notebook, both in her hand and with her text transcribed. We recommend opening images in a separate window for easier reading.
Included in her transcribed notes is the phrase “New York,” abbreviated “N.Y.” Earhart, and the unidentified male voice Betty also documented, continually repeat this phrase. It’s the last thing Earhart says, even as she’s apparently abandoning the plane as the tide rolls in. Betty also recorded the time of day when she heard Earhart. Our best tidal predictions for the area suggest that, in fact, Earhart would’ve landed at low tide, but been forced to leave the plane within a matter of hours.
There was no known reason for Earhart to be frantically repeating the word “New York,” but what if she wasn’t? What if, instead, the word was Norwich? On November 30, 1929 the tramp steamer Norwich City ran aground on Nikumaroro. The wreck was a known hazard and prominent marker for decades after. Earhart surely would’ve known of it and recognized it on her approach to what she’d have identified as Gardner Island.
Fast forward several months. Cadet Officer Eric Bevington visits Gardner Island. While there, he snaps what’s become known as the Bevington Photo — with the Norwich City in the background, and a strange object jutting up from the water to the far left.
TIGHAR was able to hunt down the original photo negatives and perform forensic analysis on them. What emerged was this result:
Compare that with the landing gear of a Lockheed Model 10 Landing Gear Installation 40650:
And finally, look at what happens when we superimpose one on top of the other:
This PDF details how the TIGHAR group found detailed photographic evidence of precisely how a Lockheed Model 10 Landing Gear installation shears and fails when subjected to certain kinds of lateral stress. If you compare the angles of failure (Page 14/15), the mangled landing gear winds up bent in similar angles to what’s seen above.
The most recent physical evidence was uncovered in 2014, triggering some additional coverage on the disaster. TIGHAR found a piece of scrap metal that has the same “fingerprint” as custom-made aluminum sheets that replaced some windows on Earhart’s customized Electra. The piece of scrap metal is the right size, rivets, and other hallmarks that identify it as almost certainly coming from Earhart’s plane. Nor is it the only artifact of note: We know that the British recovered a sextant box in 1940. While they dismissed the idea that the box could have contained an aviator’s sextant, we now know that Fred Noonan was in the habit of carrying both a mariner’s sextant and a bubble octant. The latter is used in aviation, while the former was carried as a backup tool.
The box the British found was stenciled with the number 3500 and otherwise marked with a second number, 1542. TIGHAR believes this refers to the manufacturer’s serial number for the device and the Naval Observatory code for validating that each device was calibrated properly. As they detail here, the serial number and NO number, if that’s what they were, fit perfectly into a sequence of other sextant boxes that were confirmed to have been processed by the Naval Observatory.
After decades of work, and boots-on-the-ground searches for artifacts, the TIGHAR team elected to use side-scan sonar to search the area of Nikumaroro where the Bevington Object was seen and where the debris field from the Lockheed Electra might have washed up. Initially, the team thought it had captured data that showed clear signs of a fuselage-shaped object in the sonar data. Unfortunately, subsequent analysis and a later 2014 expedition appear to have confirmed that the object TIGHAR thought it captured via sonar was actually a coral ridge. The 2014 expedition was beset by problems, including a last-minute shipping cost issue that prevented the team from shipping a backup ROV and the failure of the ROV they were able to bring.
Further analysis of the anomalous readings captured in the 2012 data revealed that they weren’t as anomalous as they appeared to be, due to variation in how side-scan sonar “sees” objects on the sea floor. See page 37 of this PDF for further details.
After it analyzed the 2012 data, the TIGHAR team hoped to find definitive proof for their theory during the 2014 trip. That didn’t happen, though technical difficulties prevented the group from performing anything like the data-gathering it originally intended to do. TIGHAR’s response to these setbacks was to straightforwardly admit that the anomaly they thought they had found might well be a coral ridge, and to acknowledge that there’s no sign of debris from the Electra at depths accessible to Scuba divers.
In this write-up I’ve had to pick and choose what I think are the most tantalizing pieces of the Earhart investigation. But the data TIGHAR has collected, sifted, and analyzed is orders of magnitude larger than I’ve even had room to mention. From on-site artifact recovery, tidal patterns, photographic analysis, sonar scans, and even trips to analyze the wreckage of other Lockheed Electras, this sprawling research project would’ve been impossible without access to the technology of the modern era. Even the mathematics used to estimate debris field scattering and the optimum methods for searching large debris fields with side-scan sonar depend on techniques developed within living memory.
Part of what makes Earhart’s story so compelling is that it took place at a time when air travel was rapidly shrinking the globe, yet technologies like radio were still in their infancy. The idea of losing an aircraft because of a mismatch between transmission frequencies, or a plane that couldn’t instantly coordinate its own position on Earth are foreign to us, thanks to sixty years of technological advancement. It’s easy to forget that when Earhart went missing, there were no policies for conducting search and rescue operations with aircraft, because few ships had aircraft, for example. There’s also evidence that the Itasca and other search vessels were given incorrect information about the capabilities of the Electra. Initially, the Itasca assumed that Earhart could still transmit if the plane had landed in the water (this was not the case). All of these miscommunications and problems stole precious time from the search.
TIGHAR hasn’t proved its theory — only discovering the wreckage of the Electra or incontrovertible evidence of Earhart’s personal presence on Nikumaroro would do that. But despite the loss of the sonar data, the overall body of evidence is significant. And it’s not particularly surprising that the team has had relatively slow progress — it’s not exactly cheap to hire ships and a crew to do research on a South Pacific island, and any search of the ocean around Nikumaroro requires the cooperation of Mother Nature. If the seas are rough, there’s no way to perform the necessary photography.
At the same time, however, recent events give Earhart’s case fresh resonance. The loss of flight MH370 in 2014 drove home the fact that while we may think we have perfected the art of tracking objects in flight, our ability to do so is sharply limited. All credible evidence suggests that MH370 deviated sharply from its intended flight plan before crashing into the Indian Ocean, but there’s no explanation as to why this occurred. With the black boxes having long since fallen silent, it’s possible we’ll never find the plane.
Finding Amelia Earhart’s Lockheed Electra wouldn’t tell us what went wrong that July morning — the plane would almost certainly be too battered and broken to yield much forensic evidence and there were no black boxes in 1937. But it would lay to rest the question of what happened to one of aviation’s pioneering spirits and most driven pilots, thanks to the efforts of a determined group of researchers and the painstaking work of decades.