plane crashes and air density

Could the recent rash of plane crashes around the world be blamed on air density experiments? A suitable carrier of say helium or methane in a predicted path of aircraft making the flight path untenable. Inert gasses could also be placed in the flight path to flame out the engine, stalling the aircraft while putting it in a nose dive.

Or while the gas is doing its thing a small emp is given off, just enough to shut down the electronics and shut the engine down. Then under no power the plane will lose speed and fall from the sky.