re: re:Model Rockets
Well, if they nearly hit an airliner, they certainly weren't aiming. These rockets, in spite of being really powerful, are not guided in any way other than by some wooden or plastic fins.
For any high powered flight, the FAA has to give approval and warns airplanes ahead of time. The BATF knows about the movement and sale of the propellents used. The hobbyists have to stay within preset altitude limits.
Now there are some rogue rocketeers out there that bend the rules but every launch I've ever been to has included scans of the sky for errant aircraft before any switch is thrown.
Art