Since Malaysia Airlines flight MH370 vanished from the radar more than 10 days ago, dozens of theories have emerged about the jet’s fate.

Initial reports of debris and oil slicks in the waters surrounding Vietnam turned out to be nothing. The revelation that two passengers boarded the flight with stolen passports sparked terrorism fears, before authorities concluded that the Iranian men were just trying to get to Europe.

With few known facts and an increasingly bizarre set of circumstances, many have turned to conspiracy theories, some of them as far-fetched as alien abduction.

Here are five theories about the missing Boeing 777 that gained traction, but haven’t convinced the experts:

1.  The (possibly hijacked) plane landed on a remote air strip

“It’s very unlikely, extremely unlikely,” said Patrick Smith, an airline pilot and author in Massachusetts, U.S., who has been debunking flight MH370 conjecture on his website.

“Even the most remote airstrips aren’t that remote,” Smith told CTVNews.ca. “You can’t just sneak in a Boeing, a wide-body jet, and nobody notices.”

Even if the plane managed to somehow land somewhere undetected, “what exactly is the point?” Smith asked.

2.  The plane was stolen

It’s an outlandish idea, but that hasn’t stopped speculation that the Boeing 777 may have been stolen, either for parts or to be used later in a terrorist attack.

Smith said neither possibility makes any sense.

“There are thousands of business jets and cargo planes that move around the world really anonymously every day,” he said. “Why not use one them instead of stealing a passenger plane from one of the most prominent airlines in the world and drawing the entire world’s attention to what you're doing?”

As soon as talk of a possible theft emerged, other experts quickly pointed out that it would be virtually impossible to steal a commercial jetliner and sell off its parts, which are all marked with serial numbers and tracked by their manufacturers.

3.  Flight MH370 “hid” below another plane

A self-described “hobby pilot and aviation enthusiast” attracted some attention by theorizing on Tumblr that the Malaysia Airlines plane, with its communication system turned off, may have flown “in the shadow” of a Singapore Airlines jet to avoid military radar detection as it passed over India, Pakistan and Afghanistan. 

“It would be extremely difficult to do that,” Smith said.

The theory doesn’t explain how the Malaysian jet could have broken off from the other flight to land undetected, he said.  It would have also been “very difficult” for the plane to keep pace behind another jetliner and not get picked up by its radar altimeter, which measures a plane’s exact distance to objects below it. 

The other plane “would have been suspicious right from the start,” Smith said.

4.  The passengers’ phones are ringing

Distraught family members calling their loved ones’ cellphones over and over again reported something odd last week – the phones were ringing. That led to speculation that the plane must have landed, allowing cellphone towers in the area to transmit the calls.

But those who work in telecommunications and the wireless industry immediately dismissed the idea, saying the ringing often means that the network is simply trying to locate the phone.

And for everyone asking why none of the passengers made any calls if the plane was in distress, Smith said the answer is obvious: cellphones will only work if a plane is flying very close to the ground. While some jets have the technology to make cellphone calls possible at high altitudes, it’s unclear if that was the case aboard the Malaysia Airlines flight, he said.

5.  The plane flew too high and disintegrated in the orbit

“I always save that one for last, it’s so ridiculous,” Smith said. He wrote on his website that he normally wouldn’t bother with “such nonsense,” but at least five readers have asked him about it.

All commercial airlines have a maximum cruising altitude and engine power will start weakening above a certain height, Smith said.

It’s impossible for a passenger plane to fly out of the Earth’s orbit.