For each attempt, cars are allowed two warm-up laps. At that time, a member of the team is stationed at the north end of the main stretch. He or she must wave a green flag, signaling an attempt, or else the car will be waved off. The attempt can be waved off during any of the four laps by the team, driver, or race officials. (The series will wave off the run if it is obvious the run will not be fast enough to qualify and it is getting late in the day.) If an attempt is waved off after the run starts, the attempt counts towards the three-attempt limit and the previous time is still forfeited unless race officials waved off the attempt because of weather.