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Once the map is oriented and aligned to north, fill in other information as necessary as reminders. For example, airspace that may preclude balloon operations, local no-fly areas, or areas with potential landowner relations problems should be marked. If the pilot is flying competitively, he or she may elect to mark designated “targets” on the map for ease in identifying them at a later time.
Perhaps the most underutilized use of maps is predicting likely flight paths, landmarks, and potential landing sites. Using the simple technique outlined below, this field technique allows pilots accurate real time and on-site weather data for flight planning information. A pilot needs to know where he or she is going in order to plan how to get there. This is a necessary part of flight planning, and learning the basic skills and knowledge required to plot this information improves the flight experience.
Pat Cannon, a former BFA National Champion and competitive pilot, developed a technique derived from a NWS procedure (that was later modified) to plot the information obtained from a pibal reading. This procedure requires a pencil, large square graph paper, an aviation plotter, pibals, the compass used to calibrate the map, and a watch with a sweep second hand. Two assumptions are made with this procedure. First, most pibals rise at an average rate of 300 feet per minute (fpm). (A chart of pibal climb rates can be found in Appendix B.) Therefore, after 30 seconds, a pibal will be approximately 150 feet above ground level (AGL).
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F
igure 3-1C. Plotting your course.3rd pibal reading 450 feetABCD
Figure 3-8. Third pibal plot showing 330° at 1:30 minutes.
F
igure 3-1A. Plotting your course.1st pibal reading 150 feetAB
Figure 3-6. First pibal plot showing 300° at 30 seconds.
Figure 3-5. A method for determining wind speed.
Winds more than 5 kts. Winds less than 5 kts. 0° to 45° 45° to 90° Figure 3-1B. Plotting your course.2nd pibal reading 300 feetABC
Figure 3-7. Second pibal plot showing 310° at 1 minute.
Second, for the purposes of this exercise, the winds do not have any significant speed changes.
Prior to starting the plot, a scale depicting the wind speed must be established. In this example illustrated, two squares on the graph paper will represent a wind speed of 5 miles per hour (mph). In the absence of a wind meter, or other accurate wind reading, a rough estimate of the wind speed may be made using the technique shown in Figure 3-5.
To begin plotting the pibal recording information, release the pibal and track it with the compass. After 30 seconds, take a reading and make a mark on the graph paper to represent the start point. Make a second mark to represent the direction plotted. In Figure 3-6, a track of 300° at 5 mph is depicted. Label the first two points “A” and “B.” [Figure 3-6]
At 1 minute, take a second reading. The pibal will be at approximately 300 feet AGL. In this example, the reading taken is 310°. Using the plotter, draw a line 10° off the original azimuth (the A-B line), and make another mark approximately two squares away from the mark labeled “B.” For clarity, this is be labeled “C”. See the example in Figure 3-7. (NOTE: The angles in the successive graphics are exaggerated for clarity.)
At 1:30 minutes, take another reading. The pibal will be at approximately 450 feet. Using the plotter, draw a line 30° off the original azimuth (the A-B line), and make another mark approximately two squares away from the mark labeled “C.” This mark may be labeled “D” for clarity. [Figure 3-8]
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Figure 3-10. Practice pibal plots. These exercises are designed to assist the student pilot in devleoping proficiency in using the pibal plotting method. (answers on next page)
F
igure 3-1D. Plotting your course.300°310°330°True track at 450 feetyour locationADBC
Figure 3-9. A line drawn through the last two plots provides a basis to measure the angle and determine the wind at that altitude. In this case, it is 450 feet.
Although plotting can be continued as long as the pibal remains in sight, only the three points marked will be used for this exercise. Figure 3-9 illustrates the results of the above sequence.
To determine the wind directions at different altitudes, extend lines between the plotted points as shown in Figure 3-9 back through the initial azimuth. Using the plotter, measure the angle between the lines (the angle between the A-B line and the C-D line). That angle, added to the original azimuth heading, gives a good approximation of the winds at that altitude. For the example shown in this sequence, the true track at 450 feet AGL is 005°. A grid appropriate for this computation is located in Appendix B.
This exercise demonstrates a practical method for determining approximate wind directions using items readily available to most pilots. It does not require expensive handheld calculators, laptop computers, or a theolodite that costs thousands of dollars. There is some error inherent in this process that can be lessened with experience and practice, but the readings obtained by this method can offer real time, on site weather data no forecast or briefer can provide. [Figures 3-10 and 3-11]
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Balloon Flying Handbook(33)
