Flying A Turn Area Task (TAT)
by Bob von Hellens
The TAT is a complex task.† There is no single best solution to flying a TAT as each decision made is a function of time of day, selection of course line, time remaining and accurately assessing not only the conditions immediately ahead but the conditions on the next and subsequent legs of the task.†
Historically, turnpoints in a task were specified locations on the ground.† As happened from time to time, climatealogical conditions such as thunderstorms, rain or localized high winds made it difficult or dangerous to fly to the turnpoint.† Those pilots who could not or would not go to a turnpoint because of an obvious danger either landed out or aborted the task and received distance points at best.† Inherently, this was unfair as it often was simply a function of time of arrival without the capability of anticipating that a turnpoint might be obscured.†† To avoid this unfairness, the turnpoints were expanded to a circular area to permit a pilot to choose which point in the circle the pilot would use as the turnpoint.† By having a circle radius of five miles or more, most dangerous climatealogical conditions could be avoided and the pilot would be able to log the turnpoint.†
In a TAT, the CD specifies one or more turnpoint cylinder(s) and the minimum time on course.† The actual distance flown is divided by either the minimum time or the actual time on course, whichever is greater, to obtain the speed attributed to the pilot. The degree of penetration into each cylinder is a rolling consideration factoring in distance achieved, time on course and expectation of better or worse lift for the remainder of the leg(s) of the course.† For example, should you realize going into the last turnpoint that you will be well under the minimum time if you just nick the cylinder, it will be worthwhile to go well into the cylinder.† The extra time will put you closer to the minimum task time and you will have more miles.
Under the present rules, your time on course begins when you penetrate the perimeter of the start cylinder.† Should you go out on course and then decide that your timing was off, you can restart by returning and re-entering the start cylinder.† Your decision to restart might be because of adverse conditions or because you started at a lower altitude than you could have.† Thereafter, you may (immediately or later) again exit the start cylinder and get an updated start time.† This process may be repeated any number of times. †
You may start at any point along the perimeter of the start cylinder.† Setting a course line directly toward the center of the next turnpoint cylinder is not always best.† Instead, you may decide to start to the left or right of the course line as a function of: a) the thermal you are in close to the perimeter; b) the perceived strength of a thermal under the next cloud you intend to work; or c) the next gaggle you intend to join.†
The finish is a line (gate) as determined by the CD.†† When you cross the finish line at any location therealong, your time on course stops.† Therefore, the location at which you cross the finish line should be a function of a line of lift approaching the finish line from the preceding turnpoint in order to optimize your flight path by flying through lift, which will also enhance your speed.† The minimum altitude at which you finish may be set by the CD for safety reasons.†
Aside from the start cylinder and finish line, a TAT has a cylinder around each turnpoint with a radius defined by the CD at the time the task is declared, whether at the pilotís meeting, at the flight line or after takeoff and prior to opening of the task.† To achieve a score for a completed task, you must penetrate the perimeter of each turnpoint cylinder and your logger must have at least one data point within the turnpoint cylinder.† This requires some knowledge of the frequency of data points of your GPS logger to ensure that you are within the turnpoint cylinder for the number of seconds required by your logger to record a data point.†
A TAT is a speed task, not a distance task.† While this seems elementary, some pilots fly deep into a turnpoint cylinder in weak or sinking conditions in order to increase the number of miles flown.† However, the cost of working weak thermals to make distance miles significantly increases the time on course and reduces the average speed for the task.† This is a real detriment in a TAT.
As each turnpoint has a relatively large cylinder associated with it, it provides an opportunity to fly a course line that will maximize use of visible areas of lift (typically clouds, other thermaling ships or a line of dust devils).† Thus, it is possible to deviate significantly left or right of a direct course line to optimize use of lift and achieve a higher speed for each leg.† The additional distance achieved if one penetrates the turnpoint cylinder left or right of course line is generally beneficial if one can work strong thermals or can fly along lines of reduced sink, or even lift, by such deviation.† Penetrating deep into a turnpoint cylinder is almost never warranted unless there are obvious signs of the same or better lift than the lift encountered to the turnpoint or better than the lift expected along the next leg.†
A TAT usually has at least two turnpoints.† In selecting a course line to a turnpoint, the pilot should take into consideration the expected course line along the next leg.† Thus, if the next leg has visible signs of good lift along it, the location for penetrating the perimeter around a turnpoint should be adjusted.† That way, you will be as close as possible to the line of lift along the next leg and thereby avoid as many areas of sink as possible.† If the line of lift extends a significant distance into the turnpoint cylinder, you might consider flying deeply enough into the turnpoint cylinder to intersect the line of lift close to where it begins and thereby have a longer leg in lift.†
A TAT can be flown on any of many different levels. You could simply nick each turnpoint cylinder and hope that your time is not too far under the minimum time as the speed achieved is a function of such minimum distance flown divided by the minimum time.† Or you could make decisions as to which turnpoint cylinder(s) to penetrate the deepest as a function of the perceived level of lift in each of the turnpoint cylinders to increase the distance while working the best lift or lines of lift to and from each turnpoint.† Thus, the TAT allows you the freedom to choose a course line with a likelihood of lift and thereby reduces the chance of landing out.
With complexity comes freedom.† With freedom comes elation.
© C.R. von Hellens, 2006