http://www.xcontest.org/xrace/about-aat/

The principle is simple, instead of waypoints there are sectors
(large), pilot must fly through all sectors in sequence given by organiser and
make the goal - but it is up to the pilots how deep in each sector to fly to
have longer distance (better average speed, as the time denominator is limited
by the minimum or maximum time value declared for the task ). Distance is
calculated as in online contests by tracklog optimization - for scoring it takes
farthest points in every sector to get the best distance across all sectors.

Check out the example given.