Most unreliable American airports

Long security and screening lines are just another part of travel we brace ourselves for. When it comes to security delays, Los Angeles International again takes the top spot, responsible for 8% of all delays of this kind at major airports.

August is the lead month for delays, with 11% of all security delays.

The best time to travel without a long wait through security? February, just 3.7% of all security delays occur at major airports.

Launching into late flights owing to the national aviation system—delays that result from airport operations, heavy traffic, and air traffic control—we see the majority of this type occurring at San Francisco International Airport. Roughly 11% of all NAS delays fly out of SFO.

San Francisco International is also the least punctual of all major airports when the elements outside take a turn for the worse, accounting for 8% of all flights delayed due to the weather.

Among categories of flight delays, California gets a pass for delays within the control of the air carriers themselves. Across the nation, flights can be held up by cleaning and aircraft maintenance, waiting on a late crew, or helping passengers who need it down the aisle.

The majority of air-carrier delays at major airports took place at Hartsfield–Jackson Atlanta International. Hartsfield–Jackson claimed 9% of delays of this type, affecting 13,936 flights in and out of this airport.

Not everyone who travels passes through major airports. The nation's smaller runways carry a significant number to and from their destinations.

To learn more, finder.com studied 319 minor airports—those ranking behind the major players in terms of traffic—to discover which bumped flight timing most often in the same categories.

Among minor runways, San Diego International Airport ranks #1 in flights behind schedule by 15 minutes or more, resulting in about 16,500 delays.

Northern Colorado Regional Airport, Ogden-Hinckley Airport in Utah, Santa Maria Public/Capt. G. Hancock Field Airport in California, and Tokeen Airport in Alaska all reported no delays of 15 minutes or more in 2017.

Unlike major airports, where the majority of these delays occur in June, minor airports experience the most delays of 15 minutes or more in January. The first of the month saw 18% of all delays in 2017.

The fewest delays of this type at minor airports occurred in November, accounting for only 5% of flights behind schedule by a quarter-hour or more.

When choosing among airlines, note that Allegiant Airlines accounted for only 0.10% of all delays of 15 minutes or more at minor airports, whereas Southwest Airlines accounted for 25% of such delays.

Those flying in or out of San Diego International Airport not only are more likely to experience flight delays of 15 minutes or more but also more likely to find themselves waiting due to air-carrier and national aviation system delays. The airport takes the lead for reported security delays affecting 4752 flights and national aviation system delays affecting 4255 flights.

Among minor airports last year, Alaska's Ted Stevens Anchorage International Airport experienced the highest number of security delays, accounting for almost 11% of delays of this type.

Weather can be the most unpredictable culprit of delays, and Florida's Tampa International is #1. About 455 flights were delayed in Tampa due to weather—or 4% of all reported weather delays—closely followed by San Diego International, which saw 400 weather delays.