Delays are divided into three categories, namely "on time or small delay" (up to 15 minutes delay), "Medium delay" (15 – 45 minutes delay) and "Large delay" ( 45 minutes delay). In this way the graphic representation is more understandable as well as the possibility of directly comparing the variables related with delays. As represented one can observe that Airlines that were particularly good at being on time compared to other airlines were Delta Air Lines, American Airlines and Alaska Airlines.