Causes of Flight Delays
Flight Delays in the US
The air carriers filing on-time performance data reported that 9.13 percent of their June flights were delayed by aviation system delays, compared to 7.49 percent in May 2007; 10.04 percent by late-arriving aircraft, compared to 6.71 percent in May; 8.13 percent by factors within the airlines control, such as maintenance or crew problems, compared to 5.76 percent in May; 1.42 percent by extreme weather, compared to 0.76 in May; and 0.09 percent for security reasons, compared to 0.06 percent in May. Weather is a factor in both the extreme-weather category and the aviation-systemcategory. This includes delays due to the re-routing of flights by DOT´s Federal Aviation Administration in consultation with the carriers involved. Weather is also a factor in delays attributed to late-arriving aircraft, although airlines do not report specific causes in that category. Data collected by BTS also shows the percentage of late flights delayed by weather, including those reported in either the category of extreme weather or included in National Aviation System delays. In June, 44.97 percent of late flights were delayed by weather, up 6.92 percent from June 2006, when 42.06 percent of late flights were delayed by weather, and up 14.78 percent from May when 39.18 percent of late flights were delayed by weather.