Passenger satisfaction with airlines has declined for the third year in a row, landing at a four-year low, according to an industry-wide study released Tuesday.

The J.D. Power and Associates 2009 North America Airline Satisfaction Study found that passengers are less satisfied overall with their travel experiences. In particular, passengers are unhappy with in-flight services, flight crew and costs and fees. Their disappointment comes even as airlines have improved on-time arrivals and decreased wait times at the ticket counters.

The findings are not surprising considering most airlines instituted fees last year for checked baggage, in-flight beverages and on-board entertainment to offset higher operating costs amid a weakening economy, said Paula Sonkin, vice president of travel and real estate industries at J.D. Power and Associates.

"There's a heck of a lot airlines can do to improve customer satisfaction," Sonkin said. Increasing check-in and boarding efficiencies, for example, can translate to a more pleasant experience for passengers, while airlines also can cut costs by improving their service in those areas, she said.

Some airlines do a better job than others. Among traditional carriers, Alaska Airlines ranks highest in customer satisfaction for the second year in a row. Coming in second and third are Continental Airlines and Delta Airlines, respectively. US Airways demonstrated the worst service.

And for the fourth consecutive year, JetBlue Airways took the top slot among low-cost carriers.