Electrons, being tiny relative to atoms, are able to pass through the metal shell of an aircraft after being accelerated outside of it via a lightning strike. Aaack! I hope this is Drudge's contribution and not Wu's. Microwaves are then emitted by the suped-up electrons inside where they form ball lightning. The electron-microwave-plasma pathway also explains the size of ball lightning, since the length of the electron bunch sped up by a lightning strike matches up with the typical 20-50 centimeter diameter of the resulting microwave bubble.
I'll be looking for the paper. Have a look at the video.