If these were planes, they wouldn't fly. That's the premise behind the title.
Here's a collection of some of the stuff that never made it to the Big Pizza Box collection (and for a damn good reason).
A lot of these were recorded in the 4-track version of Attic Studio; Circa 1986 to 1989. Keep in mind, these are mostly experiments that were not considered "worthy" for any of the Pizza Box's (or any other public consumption for that matter).
When the first double CD Planes overflowed, it was time to start another collection. Here's more of the same from about 1988 through 1991.