The following information is from the Netflix documentary, MH370: The Plane That Disappeared. The second conspiracy theory is that in 2014, flight MH370 was hijacked by Russians and is still missing to this day.
To read about another conspiracy theory surrounding this missing plane, read What Happened to Malaysia Flight MH370: Part 1.
In 2014, Russia invaded and took over the Crimean Peninsula, taking it from Ukraine. MH370 disappearing would be a viable distraction from the criticism they’ve been facing about the recent invasions that Russia has been conducting.
On July 17th, 2014 flight MH17 was going to Kuala Lumpur from Amsterdam and was shot down by the Russian military in Ukraine. This quickly caused suspicions of Russia hijacking MH370 because it was implausible for two Boeing 777 to be taken down in six months, and Malaysian Airlines had not had any accidents since the 90’s.
Three Russian passengers were aboard the plane. The main equipment in the aircraft is under an unlocked hatch under a piece of carpet at the front of the first-class cabin, which anyone could pull up and get into. Two Russian men sat in economy, and the third sat in first class only 15 feet from the control room. The plane took such a sharp turn that it had to have been flown manually.
This is what likely happened for the Russians to pull this off. During the flight, somewhere over the South China Sea, someone is making a ruckus near the first-class compartment.
Then, the flight attendants hurry to see what’s going on, and one of the Russian passengers slips forward, flips the carpet, and raises the hatch into the electronics bay.
Down in the hatch, the Russian plugs into the computer of the plane’s flight control system, manually giving him complete control over the aircraft.
He waits until the plane moves closer to the edge of Malaysian airspace, and then they turn on the equipment. The plane vanishes from radar traffic controller screens, and he has complete control of the aircraft.
Then, the lights start blinking on the captain’s display and the plane suddenly banks violently to the left and neither pilot is commanding.
The Russians decompress the airplane, letting air out of the cabin, and turn the nob on the oxygen bottle the pilots rely on. The captain and copilot would lose consciousness and the cabin falls quiet.
The Russians turn the plane to the northwest and now if anyone looks at the trail they will think the plane went south when it went north.