Hot air balloons operate on the very basic scientific principle that hot air rises. Many people practice ballooning as a sport, and some people also enjoy it as a relaxing recreational activity. Generally speaking, hot air balloons are quite safe, and certainly more safe than some forms of aviation.
Before examining the safety of hot air balloons, it may help to understand how they work. Each balloon has a large bag called an envelope, attached to a sturdy gondola or wicker basket. In order to get enough lift, the air in the bag is heated with the assistance of a flame. As the air heats up, the balloon rises. The pilot can control the ascent by opening a valve to let air off, causing the balloon to drop again. When the flight is over, the pilot slowly lets out enough air to allow the balloon to drop to the ground.
Like hang gliders and kites, hot air balloons travel with the wind. Pilots have some control over their direction through their altitude, as different air currents run in different directions. Typically, pilots choose the early morning hours to fly, since wind speeds are still low. Low wind speeds make riding in hot air balloons much safer, and the flights are more enjoyable, since the balloon gently drifts, rather than being buffeted along.
The weather is the most important concern in hot air balloon safety. High winds and extreme weather such as sleet and snow are potentially very dangerous. An experienced pilot will not fly in these conditions. Good pilots also always check their equipment before beginning a flight, and they often carry backup tanks of fuel and other redundant equipment for safety.
Generally, pilots who want to fly hot air balloons must get a pilot's license. This requirement varies in different nations, but in many countries there are specific courses and examinations which pilots must take to handle these types of aircraft. A private license allows a pilot to fly with a few friends, while a commercial license permits a pilot to fly larger balloons and receive financial compensation for his or her time.
Balloon rides can be great fun, and they are very safe as long as passengers follow the directions of the pilot. People who experience vertigo or fear of heights may want to skip the experience, however.