That plane could've have done much damage
even if the hijacker had time to pack a bunch of explosives into the right seat. It was a motorglider, probably a Diamond HK-31 from the photo. Go read the specs. It's too light and flies too slow to do much damage had the idiot dove it into a building. It would've hit with a lot less kinetic energy than that Cessna 172 the Florida kid flew into a building a year ago.