Airline on-time performance dips in March

— -- The nation's 19 largest airlines reported a higher rate of on-time flights in March compared to a year ago, but their performance worsened from earlier this year, according to federal government data released Tuesday.

The airlines industry's on-time arrival rate in March was 78.4%. That's up from 71.6% in March 2008, according to the Department of Transportation's Bureau of Transportation Statistics, but couldn't top February's 82.6%. Flights are considered on time if they arrive within 15 minutes of schedule.

Monthly fluctuations of on-time rates are caused by a variety of factors that are beyond airlines' control, but aviation analyst Michael Boyd says variations in the 70% to 80% range are no cause for celebration. "78% is disastrous," Boyd says. "It means we have a 20% chance of having a defective flight. Airlines also have to pad their schedule. For a flight from Binghamton (N.Y.) to New York City, they put an hour and 15 minutes (in their schedule), not 45 minutes."

The DOT report cited several causes, including aviation system delays (responsible for 7.3%), late arriving aircraft (6.5%) maintenance/crew problems and other factors within airlines' control (4.8%) and extreme weather (0.62%).

Boyd says the Federal Aviation Administration's classification of delay causes are difficult to interpret and believes a majority of late flights are due to the aging infrastructure of the country's air traffic control system. "We don't have the infrastructure to handle the demand," he says. "We have a hub-and-spoke system. If you have a snow storm delay in Denver, it (messes) up the United system for a day and a half. There are a lot of episodic things that can happen that can affect (delays)."

The industry's on-time performance has been steadily improving since the second half of 2008, when airlines started to cut capacity by turning to smaller planes and eliminating routes. Some industry watchers say processing fewer passengers has allowed airlines to improve their on-time performance. Boyd disagreed, saying the trend is a "coincidence." "If you're not there on time, they leave."