|Air carrier delay||30.4|
|National aviation system delay||25.7|
|Aircraft arriving late||39.4|
Note: A flight is considered delayed when it arrived 15 or more minutes than the schedule. Delayed minutes are calculated for delayed flights only. When multiple causes are assigned to one delayed flight, each cause is prorated based on delayed minutes it is responsible for; the displayed numbers are rounded and may not add up to the total.
Source: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, Airline Service Quality Performance 234 as of Dec. 2011.