Skiing is an essential feature of the Tribes franchise that sets it apart from other games. It involves using the slopes on a map to quickly accelerate and move around more quickly. Used in concert with the jetpack, skiing can allow players to cross even large maps in seconds, leading to Tribes: Ascend's claim to the title "World's Fastest Shooter".
Skiing dates back to the beta of the original game in the franchise Starsiege: Tribes. At that time, players had jetpacks to move around the map, but had to run or use a vehicle to travel long distances. Many of the maps were large even compared to those in Tribes: Ascend, leading to fairly slow attacks on enemy bases. Early on, the players learned that if you spam the jump button while on the side of a steep hill, the game's physics would propel you down the hill and allow you to fly extremely fast across the map. When this technique was first used, it was widely believed that players were cheating somehow.
Players used the in game client side scripting language and greatly improved the efficency by automating the 'jump' command, sending it hundreds of times a second. These scripts became a necessity to download alongside the game, or code yourself. Some players believed that including 'crouch' commands improved their speed, made them harder to hit, or just looked funny.
Meanwhile, other players had already been using the spinfusor's explosive knockback to accelerate themselves. Used with Tribes' jetpacks which allowed them to fly, players could now travel across maps faster than they could with vehicles. Eventually, use of these methods became commonplace on Tribes servers and Skiing was born.
When Tribes 2 was released, skiing had been incorporated as an actual feature in the game. Many maps were designed with skiing in mind, containing large rounding hills perfect for practicing. The game also had a training mission explaining how to ski for new players.
"Any fool can slide down a hill..." Quote from in-game training.
While the basics of skiing are easy to learn, using the technique to accelerate to high speeds can take a lot of practice. Generally, skiing involves starting with a large drop to build up speed from gravity. At the bottom of this drop a player must land on a slope which will convert the downward momentum into horizontal speed. When the slope changes from down to uphill, the player must use his jetpack to maintain momentum. The art of skiing is in learning to jet just enough to reach the next hill, and to always land on a downward slope thereby increasing overall speed.
Disk-jumping is another aspect to skiing that can be difficult to master. It involves using a spinfusor or other explosive to gain additional speed. A player must already be moving for this to be effective. While moving, the player fires his spinfusor at the ground behind him and lets the weapon's knockback push him forward even faster. In Tribes: Ascend, the Impact Nitron used by the Pathfinder class can also be used for this purpose, since it has low damage but large knockback.
Beginner Skiing Guide by Zeromethanol (DoubleCrossGaming)
Nitron- & Disk-Jumping by TheSmallKiwiBird