A+ Challenges are one of the unique event types in Wipeout 2048. It is the only event type that features the fastest speed class in the game, A+ Class.
An A+ Class Challenge node can be unlocked by ranking up, starting from Rank 24, then search for the hidden chevron (^) node which can be barely found somewhere on the Single Player Campaign event select screen to access it. There are 10 challenges, one for each track. A+ Challenge race is by far the most difficult event type as it consists of a 10 lap race and the opponents are tougher to beat that any casual/inexperienced racer will be likely to fail. But getting the effort right to Elite Pass the event will help you boost up Ranks.