American Airlines was the tardiest airline by a landslide this September

American Airlines had the lowest percentage of on-time arrivals this September, according to the U.S. Department of Transportation’s Air Travel Consumer Report released today. Only 58 percent of AA flights arrived on time and 3.1 percent of its flights were cancelled.

Weather is the most common cause of delays for carriers as it plays a part in both aviation system delays and extreme weather warnings. Factors within the airline's control, such as maintenance and crew problems, are the second most common cause.

In the case of American Airlines, factors within the airline's control are the primary cause of the exorbitant delays. AA believed that its pilots were intentionally delaying flights by writing up last-minute maintenance issues to protest new work and pay rules imposed by the airline. The Allied Pilots Association claimed they were not behind the delays.

Overall on-time arrival rates were an improvement 

Overall, airlines’ on-time arrival rates improved over August, but were lower than September of the previous year. The number of monthly consumer complaints varies in proportion to the number of on-flight arrivals, proving delayed flights equal unhappy flyers.

ExpressJet Airlines was second in line for the worst on-time performance with 81 percent of flights arriving on time, followed by United Airlines with 82 percent of on-time arrivals.

On the other hand, 96.4 percent of Hawaiian Airlines flights arrived on time making it the most punctual domestic airline, followed by AirTran (90.9 percent) and Delta (89.7 percent).

[gview file="http://www.dot.gov/sites/dot.dev/files/docs/2012NovemberATCR.pdf"]