A week after Malaysia Airlines Flight 370 vanished in mid-flight, hobby pilot and aviation enthusiast Keith Ledgerwood decided to investigate theories related to its disappearance. Armed only with available civilian radar and amateur knowledge, he found unusual coincidences and decided to share them with the world.

His blog post contending that MH370 shadowed another aircraft went viral and is considered one of the more plausible, if dauntingly intricate, alternate theories about what happened to the plane.

Ledgerwood proposed that MH370 didn't fly south, as is the consensus among experts based upon available data. Instead, he says, it headed north and flew in the shadow of another commercial flight, Singapore Airlines Flight 68, which was en route from Singapore to Barcelona at the time. This would effectively cloak MH370’s radar signal and prevent it from being detected, he wrote.

Ledgerwood’s theory is among countless attempts to explain what happened to the Boeing-777 with 239 people onboard. Suspected terrorism, government cover-ups, pilot suicide, mechanical failures and even an alien abduction scenario have all been proposed by observers who range from technical experts to former pilots, government officials and armchair analysts who may or may not have an informed clue. The lack of proof makes it impossible to prove or disprove any of them. Theoretically, anything is possible.

Ledgerwood, a 30-year-old IT professional from Cincinnati who has a pilot’s license and has flown air simulators since he was a teenager, decided to go public with his idea after concluding that no one else had proposed a logical explanation.

“No one in the media, no Malaysian official had published anything up to that point or spoken to the fact that the aircraft was anywhere near the Singapore Airlines flight at the time of its disappearance,” Ledgerwood told International Business Times.

Soon after he published the blog post, Ledgerwood was being cited in news articles and contacted by experts who wanted to determine the credibility of his theory.

“The theory stayed plausible,” Ledgerwood maintained. His scenario describes how the plane would fly undetected by radar beneath the Singapore Airlines commercial jet -- either controlled by the pilot or co-pilot for presumably criminal purposes  -- until it lands in China’s Xingjian province, Kyrgyzstan or Turkmenistan. These locations line up with the Singapore Airline's 7.5-hour flight time and the last known ping emitted by MH370, he said.

He sent his findings to Inmarsat, the satellite communications company that helped triangulate the hourly pings the aircraft sent to its satellites. According to Ledgerwood, the company pulled satellite data from both MH370 and the Singapore Airlines 68 to see whether his theory held up. He says his analysis got shelved when the company used the Doppler Effect and determined that the plane’s flight path most likely headed south and that the Boeing-777 crashed somewhere in the southern Indian Ocean.

For Les Abend, a Boeing-777 pilot who has worked for a major U.S. airline for 30 years (he declined to name the airline), Ledgerwood’s scenario is “total nonsense.” Not only would the Singapore Airlines flight be aware of MH370’s presence using its onboard equipment, but the timing would have to be exact, he said.

Robert Mann, a veteran airline industry analyst with expert knowledge in air traffic control systems, has yet another take. He said it’s possible the MH370 could have shadowed another aircraft of similar size, but that the maneuver would be extremely complex.

Since both of the aircraft’s radar devices were off (for reasons that have yet to be determined), it’s conceivable that the plane could approach another without detection, Mann said.

“It’s, in theory, possible,” he said. “The question is, can you expect a commercial pilot to fly close in trail to another commercial aircraft? It’s at night and formation flying is difficult to begin with in a small aircraft. It’s particularly difficult in a large aircraft where you have trailing wind vortex and other considerations.”

Ledgerwood isn’t the only “amateur” who has authored an MH370 theory. Nigel Cawthorne, a journalist based in Britain, recently wrote a book about the plane’s disappearance in which he outlined many of the conspiracy theories that have emerged.

The book, published less than 11 weeks after MH370 vanished, has been criticized as insensitive, premature and conjectural. Cawthorne has sought to defend himself against these claims, including on an Australian television show on which the co-host read a sentence from the book that asked, “Did they die painlessly unaware of their fate or did they die in terror in a flaming wreck crashing from the sky at the hands of a madman?” Cawthorne conceded the passage was “colorful.”

In an email to IBTimes, Cawthorne said the timing of the book’s publication was up to the publishers and that many of his detractors are guilty of some of the same accusations made against him.

“The criticism of insensitivity was leveled at me by TV presenters who are happy to run the story on their shows, which reach a far wider audience than I could ever hope to with my book. They certainly showed no sensitivity to the feelings of the families,” he said.

Another article objected to the book’s government cover-up theory in which the plane was shot down in a U.S.-Thai military exercise.

“The book did not say that. It simply raised it as one of the theories that was doing the rounds,” Cawthorne said. “I have taken all the theories and knocked them down. In my experience, governments can barely run a candy store, let alone organize a grand conspiracy. I don't believe that there are dark forces behind the scenes pulling the strings. People in power just aren't that competent.”

Jonathan Gilliam, a former FBI special agent and federal air marshal, disagrees with Cawhorne’s assessment that governments are incapable of such a cover-up. “One thing that I definitely suspect as a possibility is that Malaysia shot that plane down,” Gilliam said.

His hunch stems from one of the initial reports that described MH370 pilot Zaharie Ahmad Shah as a supporter of Anwar Ibrahim, the leader of the opposition to Malaysia’s ruling party. Ibrahim was convicted on sodomy charges hours before the doomed flight departed, and the pilot had been present in the courtroom.  

“This plane was flown by a guy who just left a sentencing of an opposition to the standing political party or administration in Malaysia. He goes from there and gets on a plane. He takes that plane, he flies and turns around and flies back at Malaysia,” Gilliam said. In such a scenario, he said, the Malaysian military would have scrambled jets to intercept it.

Gilliam cited the very lack of evidence as evidence: In his view, government officials have intentionally not located the wreckage of the plane because they shot it down.

As for reports that pings were heard from the plane’s black box during the search off the coast of Australia, which were later determined to have come from a man-made device, Gilliam argued such sounds could easily be replicated as a distraction. Pingers can be bought from aircraft suppliers and are enabled by placing them in water, he said, adding, “It wouldn’t have been difficult to throw one of those off a ship in 20,000 feet of water and cause hysteria.”

There were also flaws in the search effort itself, Gilliam said. If the plane was shot down as he posited, the search area would be located near Malaysia -- specifically off the country’s western coast.

“When the plane turned, it went back across Malaysia and north. That’s one of the only places where they never really searched,” Gilliam said. “They searched in between Malaysia and Vietnam. They searched all the way down by Australia but they never searched heavily the southwest coast of Malaysia. This is another stretch but I think it’s another plausible theory no one has looked at.”

Gilliam added that the aircraft involved in the aerial search weren't used to their full capacity. That is, since the planes had to fly more than 1,000 miles each way to reach the search area, they didn’t have enough fuel to stay in the air for long before heading back to land. Gilliam said this wasn’t necessary -- that the planes have the ability to be refueled midair, and doing so would have given them more time to survey the area.

“To have planes flying 2,000 miles and landing is kind of ridiculous when you could have sent a refueling plane there to keep them on station all the time,” he said.

Gilliam stops short of speculating about a government cover-up -- though if his theory is correct, it would mean the government covered up having downed the plane -- and says he understands why countries may need to conceal certain kinds of information.

“I’m not saying governments made the plane disappear. If they had to shoot it down and want to keep [Malaysia] from being attacked from China or causing an international incident, I can see some things being taken care of. That is as big of an assumption as saying the plane went north into Pakistan or Afghanistan,” he said.  

Abend, the pilot, maintains that the plane likely crashed due to a mechanical failure, but says he once believed the plane might have gone down in a jungle as opposed to the ocean. It was only after he spoke to one of the VPs at Inmarsat that he became convinced the aircraft crashed in water, as the satellite company claims.

“I walked through all nefarious scenarios,” he said. That includes those in which the pilots were involved in terrorism, he added.  

“The co-pilot was 27 years old, sitting right-seat in one of the biggest jumbo jets in the world. He likes his checks. He’s got the world going for him. Doesn’t make a lot of sense why he would take this airplane and ruin a great career to make a statement. There was no indication of this,” Abend said.

Then there were reports that Captain Zaharie Ahmad Shah’s wife left him, which may have led him to commit suicide, one of his pilot friends who spoke on the condition of anonymity told UK’s Express. Other suicide mission scenarios point to how one of the pilots may have steered the jetliner into a remote part of the world on purpose so their family members could still collect life insurance.

“If they never find the plane, they can’t call it suicide,” Rep. Pete King (R-LI), chair of the House Homeland Security Subcommittee on Counterterrorism and Intelligence told the New York Post.

This is what happened with EgyptAir flight 990 in 2002 when the flight’s co-pilot deliberately killed 217 passengers on board. An investigation found it was an act of revenge after he was reprimanded by the airline for sexual misconduct. His punishment forbade him from flying U.S. routes, which carry extra pay. A black box recording revealed how co-pilot Gamil el-Batouty took control of the cockpit, forced the plane into a dive, then soared it back up to 24,000 feet. The aircraft lost power and broke apart from the stress.

Abend says there’s no proof that the MH370 pilots were emotionally unstable in any way.

“If you take the captain and rumors about the fact that maybe his marriage wasn’t going great or he had girlfriends -- it’s all alleged,” he continued. “The information released from the FBI shows there’s no indications there would be motivation for this man to commit suicide or a nefarious act. It just doesn’t make sense for this man to take the airplane towards where? The middle of the ocean? For what purpose?”

As for the theory that one or both of the pilots committed suicide, Abend says that while it may be possible, he discounts it.

“If you’re going to commit suicide, there’s a hell of a lot of better ways to really make a statement. Why take 238 other people with you on this ride? It just sounds way too insane for me -- if you take it from the perspective of the crew doing it.”

Abend doesn’t believe a pilot could easily turn off the plane’s transponder – its secondary radar, which transmits the flight speed, identification tag and direction to air traffic control -- to mask its flight path. To do so would require personally descending into the plane’s electronic bay beneath the first class cabin and manually shutting it off, and as a pilot himself, Abend said he would have no idea how to do that.

“I don’t even know where it is. That’s why in the back of my head I’m always saying something mechanical happened,” he said.

For Abend, one of the theories that may fit all the facts is a fire caused by the cargo on board. A cargo manifest for MH370 included 5,440 pounds of batteries.    

“To the best of my knowledge they were loaded in the forward baggage compartment. You can access the forward baggage compartment from the EB (electronics bay) compartment. If a fire were to ignite, who knows what it would have burned through,” he said.

Abend isn’t the only pilot to propose a fire-based theory. Chris Goodfellow, an instrument-rated Florida pilot, wrote a blog post that assumed an electrical fire onboard. In his explanation, the plane’s sudden 90-degree turn left was intended to direct the jetliner to a runway on the island of Langkawi after a fire broke out in the cockpit. To stop the fire, the pilots pulled the circuit breakers, which would explain why both radar systems were turned off. The scenario ends with the men unconscious and the plane flying “on deep into the south Indian Ocean” until it ran out of fuel and crashed.

Goodfellow’s theory has been questioned, however, because the plane made two other sharp turns that would've been impossible if the pilots were unconscious. There was also an electronic ping detected by the Inmarsat satellite that placed the plane on two arcs that wouldn't take it near Langkawi without human intervention, Slate’s Jeff Wise pointed out.

MH370_satellites Satellite data has allowed amateur investigators to map the possible paths of MH370. Photo: International Business Times/Hanna Sender

As outsiders continue to speculate on what happened to MH370, the passengers’ families have begun to doubt the official findings. On June 9, several relatives started a crowdfunding campaign to raise $5 million to spend on an independent investigation to find answers.

"The official investigation being run by governments and agencies has failed to find the plane, due to either incompetence or obfuscation. We must work together to ensure the truth is found,” Sarah Bajc, the girlfriend of passenger Philip Wood, said on the campaign’s website, which has raised more than $24,000 so far. “On behalf of the 3.1 billion people who fly every year, we must find the truth and bring those accountable to justice. We must also prevent this from ever happening again."