By Nico Grant

While oil prices dropped by half over the past 2.5 years, average U.S. plane ticket prices decreased 8.6 percent during the same period.

That disparity has spurred passenger and industry concerns about pricing by the major airlines, including Delta, whose new CEO, Ed Bastian, has faced a challenging first year.

Stocks dipped Friday as Delta, which runs flights out of New York’s major airports, canceled hundreds of flights with Hurricane Matthew bearing down on the Southeast. The Atlanta-based carrier faced a bigger crisis in August, when a power outage at its data center stymied its global operations – grounding thousands of flights over two days.

Delta also has come under fire for changing its popular SkyMiles program in recent years, requiring travelers to meet spending benchmarks in order to earn top benefits, rather than simply accruing miles flown. Chief rivals American and United implemented similar systems after Delta set the bar.

But Bastian, noting his company has poured $4 billion into bolstering service in the last year, says customers remain high priority.

“We’ve got a lot of investment we’re making to continue to improve our experience,” he said.