Notes: A flight is considered delayed when it arrives 15 or more minutes later
than the scheduled arrival. 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 to the total.
Source: U.S. Department of Transportation, Research and Innovative Technol- ogy Administration, Bureau of Transportation Statistics, Airline On-Time Sta- tistics and Delay Causes available at http://www.transtats.bts.gov/OT_Delay/ OT_DelayCause1.asp accessed August 2012.