The Jump Pack power-up has been broken since 2012 or before -- need citing.
This Power-Up enables you to perform a special jump that moves farther and faster than a normal jump. This is a very effective tool for flag runners as it provides players with a slight speed advantage over other players in the game. In order to perform this jump, while moving forward you must hold down the crouch key, and quickly press the jump key.
NOTE: The OpFor CTF Jump Pack differs from the Half-Life Jump Pack in that this item (like all other OpFor CTF Power-Up items) can only be carried by one player at a time. However, it still offers great increase in speed and mobility when used properly and can be one of the most effective Power-Up items a flag runner can employ.