[Nick_C]

Well, commercial airliners don't have radar that would necessarily pick it up.

I must admit, I'm a little gob-smacked that he just launched without a clearance from the FAA, but I don't have a map of the airways there so perhaps it was outside controlled airspace. Even so... whew.

[dkokelley]

The radar is not for the planes. The controllers on the ground look at the big picture and direct traffic for appropriate separation requirements. It's their radar that would pick up the craft.

Nobody actually gets "clearance" from the FAA. The administration sets the framework and guidelines for operation. This would fall under an unmanned aircraft of some sort, and would be subject to the airspace regulations it operated in. Believe it or not, hot air balloons actually have the right of way in any airspace since they are the most difficult to control.

[Nick_C]

The issue is that the FAA has a procedure for anyone who wants to launch a pilotless balloon (or rockets, etc) that involves getting pre-approval, then clearance on the day. It is to allow them time to issue the appropriate NOTAMs.