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• Flying in precipitation is a bad practice. Rainwater (or any frozen precipitation) on the balloon causes it
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Figure 3-3. Sectional chart depicting the Atlanta-Hartsfield-Jackson International Airport Class B airspace.
to get wet and become heavier, often to the point of being unable to maintain altitude without exceeding temperature limitations of the envelope. A wet envelope heated to flight temperatures can be seriously damaged because the heat often causes fabric coatings and treatments to degrade, decreasing the life of the fabric. If a balloon gets wet, it should never be dried out by the application of heat to the point of equilibrium, or neutral buoyancy.
• Precipitation also often causes the atmosphere to become increasingly unstable. Downdrafts, wind gusts, and the possibility of hail and lightning follow. The pilot may be the last one to know that it is raining because the balloon will shield him or her from the precipitation. Ground crew can detect the slightest trace of precipitation before a pilot does, and need to communicate this information immediately to the pilot. In the face of possible precipitation, cancellation of the flight is the best plan.Navigation
Navigation of a balloon is unlike that of any other aircraft because it cannot be steered in the conventional sense. Directional control is achieved through the use of differing wind directions at different altitudes. With effort, study, and some practice, it is possible for a balloon pilot to determine a point on the ground at some distance, and fly to it with relative ease and accuracy.
The first step in learning balloon navigation is understanding the maps used in balloon flight. Two types of maps are used: sectional aeronautical charts and local topographical maps. Both have their uses and each has advantages and disadvantages. Another type of map may be available to the balloon pilot. This is a local area map developed by the local balloon club which shows prohibited zones and sensitive areas.
Sectional aeronautical charts (or sectionals) are published on a routine basis by the National Aeronautical Charting Office (NACO), a division of the Federal Aviation Administration (FAA). [Figure 3-3] These charts are at a scale of 1:500,000 (one inch representing 500,000 inches on the ground, or about 7.9 miles), are similar to an automobile road map, and provide useful information to a balloon pilot flying under visual flight rules (VFR). Charts are generally named for the most prominent city contained within the area of the sectional chart.
There are also sectional charts with a smaller scale, 1:250,000, to represent the areas immediately surrounding Class B airspace, which is the airspace surrounding major air traffic facilities in the United States. Airspace is discussed in detail in Chapter 5, The National Airspace System. These charts (commonly referred to as terminal area charts) show a significantly increased level of detail, and, if available, may be of more value than a standard sectional.
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Figure 3-4. Detailed topological map.Sectionals depict many different things, including controlled and uncontrolled airspace, airports, major roads and highways, cities and small towns, etc. They also indicate obstacles to flight, such as major transmission lines, radio, TV, and water towers, smokestacks, and other items. The legend of the sectional provides a means to identify these landmarks. A more detailed explanation of sectionals and the information they contain, is found in the FAA Aeronautical Chart User’s Guide, a publication of the NACO. This publication may be found at many pilot supply stores where sectionals are sold, or may be purchased online, along with the maps themselves, at www.naco.faa.gov.
Pilots review the sectional chart and familiarize themselves with the airspace they may be using when flying in a new area or refreshing their memory of a frequently flown area. The sectional helps a pilot determine obstacles to flight (towers, powerlines, etc), as well as locating landmarks for use during the flight. While sectionals offer much valuable information on an area, their lack of resolution on a small scale means they do not provide enough information for a balloon flight. The length of the average balloon flight is 6 to 8 miles. On the sectional, this equates to the distance between the first joint and tip of one’s thumb. This lack of significant detail is a disadvantage for navigation in a balloon, but sectionals are useful as a source of general information about a given area.
A good topographic chart, such as the commercially available United States Geological Survey (USGS) maps offer more value to the balloon pilot. These maps depict information on a relatively small scale and are more useful to the balloon pilot. They show individual terrain features such as roads and road networks, built up areas, schools and churches, and will indicate wooded areas, as well as open pastureland. [Figure 3-4]
With any map, it is important to insure the map is current and has an accurate depiction of north. To check the orientation of a map, select one particular road or feature with a specific directional orientation. Then orient the map to that feature, matching the direction of the road with the map. Place a compass (preferably a sighting compass) on the map to determine the azimuth. Use the same compass that will be used for computing the flight path. Ensure that nothing is affecting the compass reading. It is important to distinguish “true north,” used by most cartographers, and “magnetic north,” as indicated on the compass. Once the azimuth is established, sketch a compass rose, or place a “stick-on” type compass rose on the map.
　
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