The regulations surrounding high-altitude ballooning are not difficult to follow, and really not that difficult to read.  It's essential that you read and understand these regulations prior to flight (otherwise you run the risk of spoiling the fun for everyone).  The primary regulations are for "unmanned free balloons," and are found in a regulatory document frequently referred to as FAR-101 (FAR stands for Federal Aviation Regulations, click here to read the full text).  In addition to operating in accordance with the letter of the law, use common sense.  For example, even if you're flying an "exempt" flight, don't launch into busy airspace.  If your predictions indicated that you're going to land in busy airspace, move your launch site or change your lift characteristics to avoid the areas where you might cause an increased level of danger to air traffic.

If you're planning on using a cell phone to track your payload, PLEASE DON'T.  It's illegal, and there are better ways of tracking your payload anyway.  Discussions abound regarding whether or not this regulation is outdated or not, but it's on the books.  We can work to get it changed, but civil disobedience is probably not worth it on this point.  This isn't a grey area, it's very clear (espescially for leagalspeak): click here to read this regulation.

Finally, note that this is not an exhaustive list.  It's up to you to be sure that you are operating within the bounds of the law when you fly a high-altitude balloon.

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