Airline passengers frequently deal with delayed flights. While inconvenient, delays are often unavoidable due to various factors that interrupt scheduled itineraries. Since 2003, the U.S. Bureau of Transportation Statistics has compiled ongoing reports on the causes of flight delays, using five broad categories established by the Air Carrier On-Time Reporting Advisory Committee to classify all occurrences.
Air Carrier Delays
Air carrier problems rank among the most common causes of flight delays. Air carrier issues accounted for 30.4% of all reported flight delays in 2010, according to the U.S. Bureau of Transportation Statistics. Causes of delays within airlines' control include troubles with baggage handling, fueling, cleaning, general maintenance, crew problems and other similar difficulties. Such mishaps typically take place due to errors committed by airline personnel, though some problems, like unforeseen mechanical breakdowns, cannot be avoided.
Late-Arriving Aircraft Delays
The U.S. Bureau of Transportation Statistics lists late-arriving aircraft as another major delay category. Data shows that 39.4% of flight delays in 2010 occurred because of late-arriving aircraft. A ripple-effect of delays often takes place when a given aircraft arrives late from one destination and therefore takes off later than scheduled for its ensuing departure. In many cases, aircraft arrive late because of errors caused by airlines themselves. However, travelers must remember that uncontrollable factors such as extreme weather also play a big role in late arrivals.
Extreme Weather Delays
Extreme weather contributed to 4.4% of flight delays in 2010, according to the U.S. Bureau of Transportation Statistics. Planes are designed to withstand harsh climates and usually fly at altitudes high enough to avoid choppy conditions. Even so, extreme weather can make it dangerous for planes to fly, take off and land. In some cases brief delays occur because of passing thunderstorms or hailstorms. Exceptionally severe conditions such as blizzards and hurricanes can cause more extensive delays.
National Aviation System Delays
National Aviation System delays include a wide range of factors such as airport operations, high air traffic volume and non-extreme weather conditions. Major hubs with heavy air traffic congestion often experience delays as myriad airlines attempt to utilize limited runway space and coordinate with airport tower controllers. Delays in such circumstances technically count as National Aviation System Delays. According to the U.S. Government Accountability Office (GAO), any non-extreme weather condition that slows down the operations of air traffic but does not prevent flying can also be grouped into this category. For instance, strong winds or thick fog would qualify for this category as non-extreme weather conditions that cause airport controllers to reduce the speed of operations as a safety measure. Data from the U.S. Bureau of Labor Statistics indicates that 27.5% of delays fell into the National Aviation System category in 2010.
Some flight delays take place due to security issues. Airport security measures have increased significantly following the September 11, 2001 terrorist attacks. Suspicious activity and unidentified objects can cause security agents to close down or evacuate entire terminals until potential threats have been cleared. Agents may also ground flights and board aircraft to investigate security breaches. Thankfully, such cases are rare. Security delays accounted for just 0.2% of all flight delays in 2010, according to the U.S. Bureau of Transportation Statistics.