to create enough heat to warm up the balloon quickly. It is most efficient only when wide open. There is no good way to maintain the exact temperature required to maintain equilibrium. Add to that the fact that when a hot air balloon is not actively being heated, it is cooling off. This means that it is in perfect equilibrium only momentarily. The rest of the time it is either too warm or too cool and so either climbing or descending. These two facts together mean that under most conditions level flight is anything but. The goal of the pilot is to light the burner at the right interval and for the right duration (a few seconds) to keep the balloon slowly drifting up and down about the desired altitude. An exception is made when flying close to the ground, as in an approach to a landing. Then the burner may be lit for very short bursts at a much higher frequency, thus sacrificing efficiency for accuracy. Chase While it is certainly possible to enjoy the sport of hot air ballooning without a chase vehicle, returning from the landing site by foot, bicycle, or hitch hiking, many balloonists opt to be followed by their ground crew in some sort of chase vehicle. Crew at the landing site can aid with the landing itself, by catching a drop line and guiding the balloon into a tight space; with extracting the balloon system from a remote location, such as deep in a farmer's field; and with packing up all the equipment. Sometimes, a chase vehicle may be equipped with a trailer, which can provide more room at the cost of being more difficult to maneuver. A pickup truck or van by itself can be more maneuverable but at the cost of squeezing all the equipment, crew, pilot, and passengers into a single vehicle. Many chase vehicles are fitted with a cargo liftgate to aid in loading heavy equipment into the cargo space (the envelope itself can weigh 250 lbs or more). Communication between the balloon and chase vehicle can be accomplished by two-way radio, or even shouting, when they are close enough together. The use of cell phones for this purpose, while the balloon is flying, may violate local telecommunication laws and should therefore be avoided except in an emergency situation. Landing Most pilots try to perform as smooth a landing as