Airlines are causing more flight delays than the weather, according to data provided by the airlines to the Department of Transportation's Bureau of Transportation Statistics. Airline delays caused by computer glitches, mechanical breakdowns, a lack of flight crews, or any number of internal problems caused delays of 20.2 million minutes in 2015—a little over 38 years in sum.
Airline problems exceeded what is commonly seen as the main offender in flight delays, that being the weather. Weather delays only affected 0.68 percent of all flights, while airline delays affected 6.1 percent. Coming in second place was the the National Aviation System's own delays, at 5.85 percent. The Department of Transportation defines a delay as any flight that reaches the gate at least 15 minutes later than its scheduled arrival time.
Naturally, the airline industry feels that a focus on these numbers obscures the fact that most flights don't get delayed. Airlines for America, a trade group representing the industry, points to an on-time rate of about 80 percent and credits scheduling fewer flights at the busiest airports with easing congestion.
It's easy to point to reasons why most delays have fallen: tracking systems have gotten better at adapting to weather like thunderstorms, and fewer airlines after the economic crash of 2008 leaves the skies a little more open. However, airlines aren't required to report the reasons for their delays to government, so the main causes will likely remain a mystery.