Figure 11-9.  Circle Back and Needmore. Figure 11-8.  Benger Airport (X54). it may be better not to deviate. If the Cu left of course indicates  a possible area of lift compared to the clouds ahead and only  requires a 10° off course deviation, proceed towards the lift.  Knowing the present location of the glider and where the course  line is located is important for keeping situational awareness. Sometimes it is necessary to determine an approximate course  once already in the air. Assume a few miles before reaching  the town of Muleshoe, on the second leg, the weather ahead is  not as forecast and has deteriorated—there is now a shower at  the third turn point (Circle Back). Rather than continuing on  to a certain landing in the rain, the decision is made to cut the  triangle short and try to return directly to Portales. Measure  and find that Portales is about 37 miles away, and the estimated  heading is about 240°. Correct for variation (9°) for a compass  heading of about 231° (240° – 9° = 231°). The northwesterly  wind is almost 90° to the new course and requires a 10° or  20° crab to the right, so a heading between 250° and 270°  should work, allowing for some drift in thermal climbs. With  practice, the entire thought process should take little time. The sky towards Portales indicates favorable lift conditions.  However, the area along the new course includes sand hills,  an area that may not have good choices for off-field landings.  It may be a good idea to fly more conservatively until beyond  this area and then back to where there are suitable fields for  landing. Navigation, evaluation of conditions ahead, and  decision-making are required until arrival back at Portales  or until a safe off-field landing is completed. MOA can be found on the sectional chart, and the automated  flight service station (AFSS) should be consulted concerning  the active times of this airspace. Approaching the second  turn point, it is easy to confuse the towns of Circle Back  and Needmore.  [Figure 11-9]  The clues are the position of  Circle Back relative to an obstruction 466 feet above ground  level (AGL) and a road that heads north out of Needmore.  Landmarks on the third leg include power transmission lines,  Salt Lake (possibly dry), the small town of Arch, and a major  road coming south out of Portales. About eight miles from  Portales a VOR V-280 airway is crossed. The  GPS navigation systems are available as small hand-held  units. (See Chapter 4, Flight Instruments, for information on  GPS and electronic flight computers.) Some pilots prefer to  use existing flight computers for final glide and speed-to- fly information and add a hand-held GPS for navigation. A  GPS system makes navigation easier. A GPS unit displays  distance and heading to a specified point, usually found by  scrolling through an internal database of waypoints. Many  GPS units also continuously calculate and display ground  speed. If TAS is also known, the headwind component can  be calculated from the GPS by subtracting ground speed from  TAS. Many GPS units also feature a moving map display  that shows past and present positions in relation to various  prominent landmarks like airports. These displays can often  zoom in and out to various map scales. Other GPS units  allow marking a spot for future reference. This feature can  be used to mark the location of a thermal before going into  a turn point, with the hopes that the area will still be active  after rounding the turn point. After a thorough preflight of the glider and all the appropriate  equipment is stowed or in position for use in flight, it is time  to go fly. Once in the air and on course, try to verify the  winds aloft. Use pilotage to remain as close to the course line  as soaring conditions permit. If course deviations become  necessary, stay aware of the location of the course line to the  next turn point. For instance, the Cu directly ahead indicates  lift, but the one 30° off course indicates possibly even more lift,  One drawback to GPS units is their attractiveness—it is easy  to be distracted by the unit at the expense of flying the glider  11-8 Navigation Using GPS