This achievement is located on the track "Ghost Town", which is available as long as you have progressed far enough through the main career to unlock the DLC tracks (and you have to own the DLC ofc...)
Shortly after the checkpoint labeled 2, you will notice a moose head on the wall in front of a large drop. Bail out and touch the moose head to make it turn purple.
Respawn at the checkpoint, and continue until Checkpoint 3 and once you hit the loop section, slow down and you will find a glowing purple room has opened up if you drop down from it.
Simply enter the room and complete the track to unlock the achievement.