Southwest Airlines has consistently had one of the best on-time performance records in the airline industry. A critical factor in Southwest's success has been its use of second tier airports such as Midway in Chicago, Hobby in Houston, City in Detroit, and Ontario in Los Angeles. These lower traffic airports allow Southwest to have a faster turnaround for its airplanes so they spend a greater percentage of their time in the air. Seventy percent of Southwest's flights have a turnaround time of 15 minutes. Southwest Airline's on-time performance reflects the dimension of service quality.