Then you first need to know which is the longest and that is a bit unclear. The second longest and it's location is one of the runs shown below.
1) Vallée Blanche in Chamonix from Aiguille du Midi down to Chamonix. There are several different numbers given for this run between 20 and 22 km. The Chamonix home page claims 20 km. Note that this is not a piste, it's a commonly used off-piste route where a mountain guide should be used.
2) From Kleine Matterhorn to Zermatt. Ski-zermatt claims 13 km and zermatt home page claims 22 km.
3) The Sarenne run in Alpe d'Huez is often claimed as the longest piste. It's on the piste map (from the Alpe d'Huez home page) stated as 19 km but on the Alpe d'Huez home page itself it says 16 km so it's probably not the longest piste but it is the longest black piste, even though the last part of it is more transport than black.
2.5 miles (4.0 kilometer) is the longest run in Utah.
400 meters
Vikersund, which has the record for world's longest jump.
Bjørn Einar Romøren NOR 239 meters*
The alternate angle of depression is the angle of elevation and so 51/tan(6.7) = 434 ft which will be the length of the ski run providing the given information forms a right angle triangle.
ski's
Ruka in Finland one of the longest ski reasons in the world. From first weeks of October right through until June, ski lifts in Ruka continuously operate.
Mount Baker
Village Way. It starts at the top of the Panoramic lift and ends at the WP base area.
This resort in the southern Ontario region is spread out over 680 acres of land. The skiing area at this resort is 24.7 hectares (61 acres). The longest run is 670 meters (2,200 ft).
Ski jumping.
Ski Jumping