Is it true that weather causes only 6 percent of flight delays?
That category consists of extreme weather which prevents flying. There is another category of weather within the NAS category. This type of weather slows the operations of the system but does not prevent flying. Delays or cancellations coded “NAS” are the type of weather delays that could be reduced with corrective action by the airports or the Federal Aviation Administration. During the first seven months of 2007, 77.8 percent of NAS delays were due to weather. During 2007, 76.9 percent of NAS delays were due to weather. NAS delays were 27.9 percent of total delays during that time. How many flights were really delayed by weather? A true picture of total weather-related delays requires several steps. First, the extreme weather delays must be combined with the NAS weather category. Second, a calculation must be made to determine the weather-related delays included in the “late-arriving aircraft” category. Airlines do not report the causes of the late-arriving aircraft but an allocation
