Cross-Country Soaring 2004
User Guide 
7.3 Cross-Country Soaring
Gliders can fly long distances using rising air, or “lift”, to stay aloft. Much is involved in efficient cross-country flying, with the fundamental skill being the ability to find lift and effectively climb in it (see Thermal Soaring and Ridge Soaring). Several factors influence decisions made by the skilled cross-country soaring pilot, and most decisions are based partially on predictions of weather and lift conditions ahead on course.
One decision made by the cross-country soaring pilot is launch time. Too early a launch can leave a pilot landing back at launch for another flight or landing out after a short flight only to watch conditions improve. Waiting too late to launch, however, could limit the flight in the case of deteriorating conditions or simply because of limited daylight. The desired task for the day greatly influences the optimum launch time. If you want to fly as far as possible, then you'd launch as soon as conditions would support prolonged soaring flight. With a shorter, predetermined task, you might estimate the time required to achieve goal and launch at a time that would place the flight during the expected peak soaring period of the day. Often during competition, however, the choice of launch time is somewhat determined by the competition organizer/director, so the successful pilot should be skilled at working lift in even the weakest conditions.
Another important decision made by the cross-country soaring pilot is when to leave lift. It's not always in a pilot's best interest to stay in lift. Time can be wasted trying to climb in weak or small thermals if there are stronger, larger thermals around. This is especially true when flying upwind, as you will drift farther downwind from your goal when climbing in a weak thermal than when climbing in a stronger one. At low altitudes one might choose to stay in poor lift until he spots definite better lift that's within his glide range, while at higher altitudes he might choose to leave poor lift and continue on course expecting to find better lift ahead. At any point in the flight (except for the final glide, which is discussed below), lift should only be left when better lift can reasonably be expected within your current glide range or when the top of the thermal is reached. In some situations you may even choose to linger at the top of a thermal (e.g., to wait on a teammate to catch up or to wait for conditions ahead to improve).
A similar decision is made when climbing in the thermal that's lifted you to an altitude from which you can glide to goal. This last glide of the flight is commonly known as the "final glide". Leaving at lower altitudes often results in lower average speeds on final glide, which can mean lower overall course speeds. Leaving with too much altitude, however, can result in such long climb times in this last thermal that, even though the final glide speeds are higher, the overall average course speeds are lower. In general, in a weaker thermal, leave lower, and in a stronger thermal, leave higher in order to achieve the best average course speed. Races are often won or lost based on final glide decision-making. A flight computer can help you make better final glide decisions.
Cross-country soaring competition is an excellent arena for practicing maximum-efficiency and maximum-speed cross-country flying and for testing one's skills against some of the best pilots. The general format of a cross-country soaring competition is to have several pilots fly the same pre-determined course with the winner being the pilot to complete the course in the fastest time. If no pilot completes the course, then the winner is the pilot who comes nearest to completing the course. Most courses consist of at least one turnpoint, which allows the launch and landing sites to be the same if desired. Also, some competitions have an open-distance format, wherein pilots can launch whenever they choose and fly in whatever direction they want, with the winner being the pilot to fly the farthest straight-line distance.
While not all competitions are conducted using the exact same rules, there
are some common aspects of competition rules, such as those related to flying a
predetermined course. Of primary importance are the proper verification
of flight task turnpoints and the proper crossing of goal, both of which are
fairly straightforward. In many competitions today, given the use of GPS
receivers for scoring/verification, you only have to fly within ¼ mile (~1,320
ft. or ~400 m) of a turnpoint or goal to be credited with having achieved that
turnpoint or goal. If you fail to achieve a turnpoint, land as near the
turnpoint as possible in order to be credited with as much distance as possible. Your scored distance is calculated as the
total course distance minus the course distance remaining from the missed
turnpoint to goal minus the distance from your landing point to the missed
turnpoint. Thus, missing a turnpoint and
continuing on course can be a costly mistake to your score for the flight. This competition overview is given just for
general reference. CCS does not contain
flight task or competition scoring functions.