The XCSoar task file, point by point.

XCSoar is the open-source soaring computer that runs on Android and Linux, and .tsk is the file it saves a task to. It is small, plain XML, and holds exactly one task — no competition wrapper, no pilot list, no dates.

Its heritage is gliding rather than free flight, and the format's shape follows from that. It is unusually precise about the geometry of each turnpoint — the observation zone can be a line, a cylinder, a sector, a keyhole, an annulus — and about glider start constraints like a maximum start height or start speed. It is completely silent about the things a paragliding competition cares about most: no start gates, no task deadline, no dates.

<?xml version="1.0" encoding="UTF-8"?>
<Task type="RT">
  <Point type="Start">
    <Waypoint name="B02 Aujour">
      <Location latitude="44.28500" longitude="5.74000"/>
    </Waypoint>
    <ObservationZone type="Cylinder" radius="2000"/>
  </Point>
  <Point type="Turn">
    <Waypoint name="B15 Hongrie">
      <Location latitude="44.36200" longitude="5.71500"/>
    </Waypoint>
    <ObservationZone type="Cylinder" radius="1000"/>
  </Point>
  <Point type="Turn">
    <Waypoint name="B22 StGenis">
      <Location latitude="44.24000" longitude="5.84000"/>
    </Waypoint>
    <ObservationZone type="Sector" radius="800" start_radial="0" end_radial="180"/>
  </Point>
  <Point type="Finish">
    <Waypoint name="A02 Landing">
      <Location latitude="44.31900" longitude="5.82600"/>
    </Waypoint>
    <ObservationZone type="Line" length="2000"/>
  </Point>
</Task>

The nesting is strict and shallow: a Task holds Points in flying order; each Point holds exactly one Waypoint (which holds one Location) and exactly one ObservationZone. Everything is attributes.

Task types

The type value names an XCSoar task factory. The ones you meet in practice:

<Waypoint> and <Location>

This is where .tsk is richer than every other task format. The type attribute selects the shape; the other attributes size it.

Collapsing a zone to a cylinder

Formats that only model cylinders — XCTrack, and therefore most paragliding tools — need one number. The mapping that preserves the pilot's actual task:

Every non-cylinder zone that survives this is an approximation. A sector becomes the full circle it is a slice of, which makes the turnpoint easier than the file says; a keyhole loses its stem. That is acceptable for display and route length, and it is not acceptable for scoring — never re-score a flight against a task that has been through this reduction.

Search by element, attribute or meaning, or narrow by category.

Points are listed in flying order with their zone decoded and reduced to an effective radius. OptionalStart points are shown and marked as excluded. Parsed with the browser's XML parser — nothing is uploaded.

A .tsk carries geometry beautifully and timing not at all. Importing one into a competition-task model therefore loses information in both directions — some of it silently. The honest list:

We-Fly imports .tsk in the competition-task library and the XC planner. The mapping:

Files are capped at 64 KB, and a task needs at least two readable points. Exports are always .xctsk; We-Fly never writes .tsk.