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and finding lift. This can lead to a dangerous habit of focusing too much time inside the cockpit rather than scanning outside for traffic. Like any electronic instrument, GPS units can fail, so it is important to have a backup for navigation, such as a sectional and plotter. 

## Cross-Country Techniques 

The number one rule of safe cross-country soaring is always stay within glide range of a suitable landing area. The alternate landing area may be an airport or a farmer’s field. If thermaling is required just to make it to a suitable landing area, safe cross-country procedures are not being practiced. Sailplane pilots should always plan for high sink rates between thermals as there are always areas of sink around a lifting thermal to fill in the void vacated by the lifting air. 

Before venturing beyond gliding distance from the home airport, thermaling and cross-country techniques can be practiced using small triangles or other short courses. Three examples are shown in Figure 11-10 . The length of each leg depends on the performance of the glider, but they are typically small, around 5 or 10 miles each. Soaring conditions do not need to be excellent for these practice tasks but should not be so weak that it is difficult just to stay aloft. On a good day, the triangle may be flown more than once. If other airports are nearby, practice finding and switching to their 

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communication frequency and listening to traffic in the traffic pattern. As progress is made along each leg of the triangle, frequently cross check the altitude needed to return to the home airport and abandon the course if needed. Setting a minimum altitude of 1,500 feet or 2,000 feet AGL to arrive back at the home site adds a margin of safety. Every landing after a soaring flight should be an accuracy landing. 

Determining winds aloft while en route can be difficult. Often an estimate is the best that can be achieved. A first estimate is obtained from winds aloft forecasts provided by the AFSS. Once aloft, estimate windspeed and direction from the track of cumulus shadows over the ground, keeping in mind that the winds at cloud level are often different than those at lower levels. On cloudless days, obtain an estimate of wind by noting drift while thermaling. If the estimate was for a headwind of 10 knots but more height is lost on glides than the glide calculator indicates, the headwind estimate may be too low and will need to be adjusted. When flying with GPS, determine windspeed from TAS by simple subtraction. Some flight computers automatically calculate the winds aloft while other GPS systems estimate winds by calculating the drift after several thermal turns. 

It is important to develop skill in quickly determining altitude needed for a measured distance using one of the glide calculator tools. For instance, while on a cross-country flight and over a good landing spot with the next good landing site a distance of 12 miles into a 10-knot headwind. [Figure 11-11]  The glide calculator shows that 3,200 feet is needed to accomplish the glide. Add 1,500 feet above ground to allow time to set up for an off-field landing if necessary, to make the total needed 4,700 feet. The present height is only 3,800 feet, not high enough to accomplish the 12-mile glide, but still high enough to start along course. Head out adjusting the speed based on the MacCready ring or other speed director. After two miles with no lift, altitude is almost 3,300 feet, still not high enough to glide the remaining 10 miles, but high enough to turn back to the last landing site. After almost 4 miles, a 4-knot thermal is encountered at about 2,700 feet and provides for a climb to 4,300 feet. 

When using the glide calculator tool, keep in mind that these calculations account for only the glider’s calm air rate of descent. Any sink can drastically affect these calculations and make them worthless. In times of good lift, there will also be areas of strong sink. A sailplane pilot must learn to read the sky to find the lift and avoid or pass through the sink as quickly as possible. Time in lift is good and time in sink is bad. A good sailplane pilot will be thoroughly aware of that particular sailplane’s polar curves and the effects from different conditions of lift, sink, and winds. 

