The Physics That Doomed Amelia Earhart

Amelia Earhart’s fatal flight (0s)

• Amelia Earhart knew she was in trouble as the sun rose on July 2nd, 1937, and she called over the radio, stating that she couldn't see her destination, was running low on gas, and was flying at 1,000 feet (15s).
• Earhart's predicament was the result of a series of unfortunate events and bad decisions, many of which could have been avoided with a better knowledge of physics (32s).
• At the time of her final flight, Earhart was attempting to become the first female pilot to fly around the world, aiming to accomplish something scientifically worthwhile for aviation (1m0s).
• Unlike other successful circumnavigations that followed a northern route, Earhart's route would be the longest, following a path close to the Equator, which made the last part of her journey the hardest, crossing the full width of the Pacific Ocean (1m15s).
• The starting point for this crossing was Lae, a city on the eastern side of New Guinea, which was one of the world's busiest airports at the time, a hub of traffic from Asia and Australia (1m32s).
• Earhart took off from Lae on what would be her final flight at 10:00 a.m. on a hot July day, piloting her Lockheed Electra down the runway (1m44s).

How Earhart prepared for her final mission (1m52s)

• The Pacific Ocean is significantly larger than the Atlantic Ocean, with vast areas of open water and limited landmasses visible when viewed from certain angles (1m52s).
• In 1937, most planes had limited range, typically only a few thousand kilometers, prompting Amelia Earhart to remove unnecessary items from her plane to reduce weight (2m2s).
• Earhart removed insulation from her plane, which reduced weight but made engine noise overwhelming, requiring her to communicate with her navigator through written notes (2m10s).
• She packed minimal supplies, telling her husband that extra clothes and food would be extra weight and worry, and replaced passenger seats with fuel tanks to increase her plane's range (2m26s).
• The modified Electra plane had a maximum range of 6,600 to 7,200 kilometers in perfect weather, which might be just enough to reach Hawaii from Lae, but also risked falling short (2m34s).
• To mitigate this risk, Earhart needed a refueling stop along the way and identified Howland Island, a small US territory in the Pacific, as a potential location (2m58s).
• Howland Island is a tiny island, approximately two kilometers long and less than one kilometer wide, with a small population of colonists in 1937, but lacked a runway (3m7s).
• Despite its limitations, Howland Island was an ideal location for refueling due to its strategic location roughly halfway between Australia and Hawaii (3m28s).

Who was Amelia Earhart? (3m33s)

• Amelia Earhart was already famous by the time of her around the world flight, thanks to her previous achievements in aviation (3m34s).
• In 1928, she became the first female passenger to cross the Atlantic by airplane, making her an international celebrity (3m40s).
• Earhart expressed her desire to fly solo across the Atlantic, saying "Maybe someday I'll try it alone" (3m54s).
• In 1932, she attempted to pilot a plane solo across the Atlantic, heading for Paris, but was forced to make an emergency landing in a pasture in Northern Ireland due to bad weather and mechanical issues (3m59s).
• During this solo flight, she brought minimal supplies, including a toothbrush, one container of soup, and three cans of tomato juice (4m6s).
• Her adventures brought her into contact with powerful people, including the First Lady, Eleanor Roosevelt (4m48s).
• Earhart used her connections to lobby President Roosevelt to hire her friend, Eugene Vidal, to head the Bureau of Commerce, and also requested funds for a runway on Howland Island (4m58s).
• When progress on the runway was stalled due to red tape, Earhart wrote directly to President Roosevelt, who approved the project four days later, allowing three runways to be cleared (5m14s).

The flight plan (5m36s)

• Amelia Earhart had a planned destination to land, but finding the tiny island of Howland in the vast ocean would be challenging, requiring a calculated flight plan (5m37s).
• The flight plan was calculated by her navigator, Fred Noonan, using the direction of Howland, the onboard compass, air speed, and ground speed, which was determined by subtracting or adding the wind (5m46s).
• The method used to calculate the flight plan is known as dead reckoning, which involves calculating the time it should take to reach the island based on the ground speed (6m9s).
• Instead of aiming directly at the island, Earhart and Noonan intentionally picked a point either north or south of the island to ensure they could determine the direction they were off if they didn't see the island at the prescribed time (6m13s).
• They estimated the trip would take 18 hours, flying through day and night, and planned to turn north and spot the island after traveling for the calculated length of time (6m29s).
• Before takeoff, the ground crew estimated a headwind of 24 kilometers per hour, but Lae radioed Earhart 20 minutes after takeoff to warn of stronger headwinds, which she didn't acknowledge (6m44s).
• Knowing the correct wind speed was critical, as it would affect the time it would take to reach the island, and Earhart couldn't rely solely on dead reckoning to reach Howland (7m0s).

How celestial navigation works (7m13s)

• Celestial navigation was used by Noonan as an independent check on their location, involving measurements of the sun, moon, and stars (7m14s).
• Noonan used an almanac that listed 58 navigation stars and the point on Earth each one would be directly overhead for the day and time of his measurement (7m24s).
• If they were directly under a navigation star, they would immediately know their position, but generally, Noonan would measure the angle above the horizon to a navigation star and use that to work out how far away they were from the point on the Earth where that star would be directly overhead (7m43s).
• By measuring the angle to a navigation star, Noonan could trace out a circle on the globe of possible locations, and then measure the angle to another navigation star and draw out a second circle (7m55s).
• The intersection of the two circles would give them their possible location, and normally, only one of the intersections would be a plausible position (8m6s).
• Celestial navigation allowed them to continually update their location and adjust bearings as needed, but errors could accumulate over long trips (8m17s).
• Earlier in the journey, when Earhart crossed the Atlantic, they missed their intended airport in hazy conditions due to small errors in Noonan's calculations (8m27s).
• To aid navigation for the flight across the Pacific, Earhart commandeered three US Navy and Coast Guard ships: the Itasca, the Ontario, and the Swan, which were positioned at strategic points along the route (8m48s).
• The ships were equipped with radio, and the Itasca would send out smoke signals as Earhart approached to help her spot Howland Island (9m5s).

Invention of radio technology (9m16s)

• In 1937, radio technology was still relatively new, having been discovered by German physicist Heinrich Hertz in the late 1880s through his experiments with oscillating electrons in a transmitter and a receiver loop of wire with a small gap (9m20s).
• Hertz's experiments demonstrated that radio waves are transverse waves with electric and magnetic fields oscillating perpendicular to each other and perpendicular to the direction of the wave motion (9m48s).
• When the receiving loop was aligned with the direction the wave was traveling, the changing magnetic field through the loop induced an EMF that created a spark, but if the loop was facing the transmitter, there was no change in magnetic flux through the loop, and so no spark was observed (9m59s).
• Initially, Hertz did not think his discovery of wireless waves would have any practical application, but within a few years, people started sending messages using radio, and by the 1920s, radio entertainment broadcast took off (10m21s).
• Ships and planes, including Amelia Earhart's, routinely used radio to send Morse code, and some could send and receive voice messages, with Earhart having five radio antennas around her plane, each for a specific purpose (10m36s).
• The largest antenna on Earhart's plane was 76 meters long, necessary to efficiently send and receive Morse code via 4 or 500 kilohertz radio waves used by ships and remote stations (10m57s).
• Ideally, an antenna should be at least 1/4 of the wavelength of the radio wave it's transmitting or receiving to improve the efficiency of the conversion from electrical energy to radiated electromagnetic energy (11m9s).
• Earhart's trailing antenna was only around 1/8 of the wavelength but was connected to a high-power transmitter, allowing its signals to be detected over 1,000 kilometers away (11m22s).
• Two antennas on Earhart's plane were used for voice communications on higher frequencies, which require smaller antennas and can travel long distances by bouncing off the ionosphere (11m33s).

Radio waves explained (12m2s)

• Starting about 50 kilometers above Earth's surface, radiation from the Sun splits electrons off molecules, forming a layer of ions and free electrons that interact with radio waves, causing them to be reflected back to Earth, a phenomenon known as skipping (12m2s).
• Radio waves can then reflect off the ocean and back off the ionosphere, making multiple hops to travel thousands of kilometers, and aviators would typically use higher frequency radio waves during the day and lower frequency radio waves at night (12m34s).
• Amelia Earhart radioed an update to Lae four hours after takeoff on her daytime frequency of 6210 kilohertz, reporting her altitude and speed, but never acknowledged calls from Lae about the headwind, likely due to impaired receiving abilities (13m7s).
• Earhart's ability to receive voice messages was impaired, and it's possible the receiving belly antenna was broken or something in the receiving electronics wasn't working (13m52s).
• Nine hours into the flight, Earhart expected to come upon the Ontario and listened for Morse code Ns on 400 kilohertz, but heard nothing, as the original plan was for the Ontario to wait for her to radio them to request that they start transmitting (13m58s).
• However, Earhart realized she had made a mistake, as the Ontario wouldn't be able to receive high frequency signals, and sent an urgent telegram asking the Ontario to transmit the Morse code Ns repeatedly 10 minutes after each hour (14m18s).
• The purpose of the Morse code from the Ontario was to allow Earhart to use her two final antennas, a loop antenna and a sense antenna, designed to locate the source of radio waves, which was the final and most critical way for Earhart to stay on course and locate Howland Island (14m41s).
• The loop antenna works by detecting the magnetic field of radio waves, which creates an EMF and current when the loop is parallel to the direction of the waves, allowing the user to pick up the signal when tuned to the right frequency (16m4s).
• Amelia Earhart used a loop antenna to detect the repeated N Morse code from the Ontario, turning it until she found the null to determine the direction to the ship (16m53s).
• However, there's a chance that she might have gone past the ship, resulting in a null, but with the ship behind her, not in front (17m27s).
• The sense antenna was used to determine whether the ship was in front or behind, as it has a single null instead of two nulls (17m38s).
• By using the sense antenna, Earhart could check which null was correct and then use the loop antenna for navigating, as it gives a sharper null (18m11s).
• Aviators could have used the loudest signal to try to go in that direction, but it's actually easier to get a precise null, a point where the signal drops out (19m46s).
• If Earhart could hone in on the Ontario using her radio direction finding loop, that would ensure she was on course and eliminate any navigation errors (20m10s).
• However, her telegram asking the Ontario to transmit 10 minutes after each hour didn't make it to the ship in time, and since Earhart couldn't talk to the Ontario, they never sent out any signals (20m19s).
• By this point, Earhart was around halfway to Howland, with no other landing strips within 1,000 kilometers, and she would have to find the tiny island or return to Lae (20m37s).
• Multiple delays had already plagued her journey, and this was not Earhart's first attempt to fly around the world (20m48s).
• Amelia Earhart took off from California in March 1937, heading west to Hawaii, accompanied by Fred Noonan and Harry Manning, a Merchant Marine captain with expertise in radio, Morse code, and traditional navigation. (20m57s)
• The flight to Hawaii was successful, thanks in part to Manning using the loop antenna to hone in on a radio beacon on the destination island. (21m22s)
• Three days later, the trio set off for Howland Island, but the plane drifted to the right during takeoff, and despite Earhart's correction, the right wing dipped down, causing the right and left landing gear to collapse, resulting in the plane skidding out on its belly. (21m35s)
• Thankfully, no one was hurt, but the Electra took months to repair, during which time the seasonal winds shifted, requiring Earhart to fly east instead of west on her next attempt. (22m1s)
• Captain Manning left the crew, with the official reason being that he needed to return to the Merchant Marines, but rumors suggested he had lost confidence in Earhart or that Earhart believed Noonan was a better navigator. (22m13s)
• When Earhart took off again three months later, she was accompanied only by Noonan, and they had made it 80% of the way around the world. (22m33s)

Earhart makes her critical decision (22m44s)

• Amelia Earhart had to make a critical decision in the dark of night whether to continue flying or turn back due to the lack of signal from the Ontario, but she decided to fly on knowing the Itasca would be transmitting the letter A over Morse code every half hour at Howland. (22m46s)
• The Itasca was also equipped to send and receive voice signals on a range of different frequencies, which reassured Earhart to proceed with her flight. (23m9s)
• Around 6:15 a.m. local time, radiomen aboard the Itasca heard Earhart clearly, and she requested them to take a bearing on her signal, but the men were confused as they expected her to take a bearing on them instead. (23m17s)
• Earhart then began to whistle into the mic, but the Itasca's radio direction finding equipment required a lower frequency signal between 270 and 550 kilohertz, which her voice frequency could not provide due to skipping off the ionosphere and scattering in all directions. (23m29s)
• As a result, the Itasca could not find a null to determine Earhart's direction, and she only heard static in response, causing her concern that they hadn't heard anything from either ship. (24m4s)
• Earhart may have expected Howland to have a high frequency radio direction finder called an Adcock antenna array, which could solve the skipping problem, but these antennas were massive and typically only installed at larger airports. (24m27s)

Communication failures (24m55s)

• A portable high frequency radio direction finder was available on Howland Island, but the operator couldn't take a bearing on Earhart's transmissions as they didn't last long enough, and he missed parts of later transmissions due to low battery (24m55s).
• Earhart asked the Itasca to take a bearing on 3105 kilohertz and report back in a half hour, but this would have been outdated or misleading due to time zone differences (25m13s).
• Earhart used Greenwich Civil Time, while the Itasca used GCT -11.5 hours, and Howland Island used Hawaii Time, which was GCT -10.5 hours, resulting in the three parties being on different time zones (25m28s).
• Earhart's hours didn't line up with the others, and she told the Itasca she would use GCT, but this information didn't reach the radiomen, causing confusion (26m2s).
• Earhart's request for a bearing was misunderstood due to the time difference, and she likely meant to say "on the half hour" instead of "in a half hour" (26m10s).
• Earhart set specific times for transmitting and listening to avoid missing messages, as she could only power one antenna at a time (26m30s).
• The Itasca blocked Earhart's message with their own transmission, and Earhart couldn't respond on 500 kilohertz as she had removed the long trailing antenna needed for lower frequencies (26m52s).
• The removed antenna was only useful for Morse code, which neither Earhart nor Noonan were proficient in, and it was seen as dead weight after Manning left (27m8s).
• Earhart couldn't send radio waves that would allow the Itasca to take a bearing on her, but she could take a bearing on the Itasca if they sent the right frequency (27m29s).
• Before the trip, the Itasca asked Earhart to specify a frequency, and she consulted a radio expert who recommended Morse code A on 750 meters or 400 kilohertz, but Earhart mistakenly requested 7,500 kilohertz (27m41s).
• Earhart explicitly stated that if the frequencies mentioned were unsuitable, she should be informed, but no one corrected her mistake (28m20s).

“Gas is running low” (28m30s)

• At 7:42 a.m., Amelia Earhart's voice came through loud and clear, stating that she must be near the Itasca but cannot see it, and that gas is running low, as she was flying at 1,000 feet (28m33s).
• The high frequency radio direction finder on Howland was low on battery, so the radiomen didn't hear Earhart's message or take a bearing on it (28m51s).
• Ten minutes later, Earhart said she was circling but couldn't hear the Itasca, and asked them to go ahead on 7,500 kilohertz (29m1s).
• The Itasca sent As on 7,500 kilohertz, which Earhart heard, but she was unable to get a minimum reading on her radio direction finding loop due to the high frequency (29m12s).
• Joseph Gurr, a radio mechanic who worked on Earhart's plane, later stated that they knew high frequencies had limitations, including a tendency to skip and bend, creating false radio direction bearings (29m36s).
• Earhart frantically called the Itasca, asking them to take a bearing on her and answer with voice, but the Itasca explained that it was impractical to take a bearing on her voice (29m53s).
• The Itasca attempted to communicate with Earhart, but she probably didn't hear their messages due to the lack of a belly antenna, and even if they had sent low frequency signals, Earhart's loop was tuned to pick up 7,500 kilohertz (30m10s).
• Commander Thompson of the Itasca was aware of Earhart's radio direction finding limits, having received messages from George Putnam and the Coast Guard's San Francisco division, but he didn't correct the frequency she suggested (30m32s).
• The Itasca continued to try to reach Earhart, and just before 9:00 a.m., Earhart's voice suddenly burst through again (31m37s).

Her desperate final message (31m39s)

• Amelia Earhart's last message was "We are on the line 157-337. We will repeat this on 6,210 kilohertz. We are running on line north and south," indicating her desperate situation (31m41s).
• Her voice sounded as if she was about to burst into tears or scream, conveying the urgency of her situation (31m51s).
• The message was received by the Itasca, and after that, there were no further communications from Earhart (31m57s).
• The evidence suggests that Earhart ran out of fuel over the Pacific and crashed into the sea (32m9s).
• Two hours after her last message, the Itasca left Howland to search for the Electra, heading north and west (32m14s).
• The search operation involved multiple Navy and Coast Guard ships and planes and lasted for over two weeks, making it the most intensive and expensive search and rescue operation in US history at that time (32m21s).
• The operation cost around $4 million, equivalent to almost $100 million today, but no trace of Earhart, Noonan, or the Electra was ever found (32m31s).
• The lack of two-way communication due to a malfunctioning belly antenna contributed to the mistakes that led to Earhart's disappearance (32m46s).
• Theories suggest that the antenna may have fallen off during takeoff in New Guinea, but there is no physical evidence to confirm this (32m54s).

The small detail that could have saved her (33m1s)

• Amelia Earhart's plane was equipped with a loop antenna that could receive signals on a wide range of frequencies, but could only direction-find with lower frequencies (33m6s).
• If Earhart had used the loop antenna for all communications, she could have received Itasca's voice messages and taken a bearing on a lower frequency, which would have guided her safely to Howland Island (33m17s).
• Research suggests that Earhart's demise was not inevitable, and there were at least half a dozen factors that could have allowed her to land safely if they had gone differently (33m49s).
• Earhart lacked knowledge of radio systems, which would have allowed her to specify the right direction-finding frequency, while Commander Thompson of the Itasca had that knowledge but did not take responsibility to correct her (33m58s).
• The story highlights the importance of knowledge and responsibility in overcoming challenges and avoiding disaster (33m55s).
• The importance of having someone with the right knowledge who will take responsibility for getting things right is crucial in battling the inherent chaos and disorder of the universe (34m19s).
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