[jhpaul]

I am not a radar operator. My understanding is that radar reflections are related to the size, shape, and texture of an object. A normal plane will be a large blob on the return, while, for example, a B2 stealth bomber is designed with special materials and angles to appear around the size of a large bird.

So an intact jet fighter will show up as a big dot, while falling debris might look like many small dots, or be too small for the resolution of the radar display.

There's also numerous sources of interference and background noise, including from weather. So on a stormy night it might not be apparent what is debris vs water.

The article is really more of an advertisement for a TV show than journalism and doesn't give a very clear account, but it sound plausible that two dots converging and disappearing from radar could represent an in-air collision. And if over the great lakes during a storm, investigators would be looking underwater for hundreds of pieces of non-magnetic aluminum spread over many square miles.