FILE - In this April 23, 2013, file photo, a JetBlue plane takes off in view of the air traffic control tower at Seattle-Tacoma International Airport, in Seattle. Alaska Airlines and JetBlue Airways still rank highest in the annual J.D. Power survey of passengers on the nine largest North American airlines, and the firm says overall traveler satisfaction with the industry is at a 10-year high. J.D. Power said Wednesday, May 11, 2016, that Alaska ranked highest among traditional airlines for the ninth straight year and JetBlue was the top-rated low-cost carrier for the 11th year in a row. (AP Photo/Elaine Thompson, File)

Alaska Airlines and JetBlue Airways still rank highest in the annual J.D. Power survey of passengers on the nine largest North American airlines, and the firm says overall traveller satisfaction with the industry is at a 10-year high.

J.D. Power said Wednesday that Alaska Airlines ranked highest among traditional airlines for the ninth straight year and JetBlue was the top-rated low-cost carrier for the 11th year in a row.

The researchers said that satisfaction about airline cost and fees improved significantly over 2015. They credited lower fares and more acceptance of paying more for baggage and extra legroom. Widespread fees on checked bags began in 2008 but are now common and raised $3.8 billion for U.S. airlines last year.

The study's findings of happy travellers ran counter to the rising number of consumer complaints to the government about U.S. airlines. Those complaints spiked 34 per cent in 2015, although they accounted for a tiny fraction of the millions of people who fly every year.

J.D. Power reported results only for nine airlines that have at least $1 billion in annual passenger revenue, at least 40 destinations in the U.S. and Canada, and for which there were at least 100 survey responses. Smaller carriers such as Spirit Airlines and Allegiant Air were not included.

The research firm said that Alaska Airlines, which flies mostly on the West Coast and recently agreed to buy Virgin America, raised its 2015 score more than any other airline. Among other traditional carriers, Delta Air Lines ranked second, American Airlines was third, Air Canada fourth, and United Airlines last.

Southwest Airlines finished second among low-cost carriers, then Canada's WestJet, with Frontier Airlines last.

J.D. Power said the online survey covered more than 10,000 people who flew on a major North American airline between April 2015 and March 2016. Passengers were asked about satisfaction with costs, in-flight service, boarding and exiting the plane and getting baggage, flight crews, planes, the check-in process, and reservations.

News from © The Associated Press, 2016