曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
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, 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 true heading is
about 240°. Correct for variation (9° east) for a compass
heading of about 231°. The northwesterly wind is almost
90° to the new course and requires a 10° or 20° crab to
the right, so a compass 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.
NAVIGATION USING GPS
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 will display 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 be zoomed in and out to
various map scales. Other GPS units allow you to mark
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.
One drawback to GPS units is their attractiveness—it
is easy to be distracted by the unit at the expense of
flying the glider 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
never allow the glider to be out of glide range of a suitable
landing area. The alternate landing area may be an
airport or a farmer’s field. If thermalling is required just
to make it to a suitable landing area, safe cross-country
procedures are not being practiced.
Before venturing beyond gliding distance from the
home airport, thermalling and cross-country techniques
can be practiced using small triangles or other short
courses. Three examples are shown in Figure 11-8. 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.
Besides locating, entering, and centering thermals on
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：
Glider Flying Handbook(153)
