Airline passenger revenues fell about 18 percent last year, reportedly making 2009 the worst-ever year and exceeding 2001’s 14 percent decline.

According to the Air Transport Association of America, the revenue decline was due to a 6 percent drop in passenger volume and a more than 12 percent plunge in the average price paid to fly one mile, CNN Money reports.

"The global recession, accompanied by high levels of unemployment, hit air travel demand especially hard in 2009," James May, ATA chief executive and president, said in a statement.

"Anecdotal evidence suggests a positive revenue trajectory in 2010," he noted, but added that the airline industry remains vulnerable because higher fuel prices would further impinge profits.

Last December, passenger revenue was down 4 percent versus the month before.

It was the 14th consecutive month of declining sales, as traffic fell 3 percent in the month.

However, the airline sector enjoyed a pair of surprising earnings beats today when Continental Airlines and Southwest Airlines each posted better-than-expected fourth-quarter profits, Forbes reports.

The boost was attributed to rising traffic, much of which was generated by leisure travelers taking advantage of low-price fares.

While Southwest CEO Gary C. Kelly sees strong revenue and booking trends continuing for 2010, he observes “the economic recovery is tepid” and “there is no doubt 2010 will be another challenging year.”