NEW YORK - David Neeleman stepped down as chief executive officer of JetBlue Airways Corp. yesterday, giving up day-to-day control of the airline he built from a scrappy low-fare upstart into a perk-heavy carrier with nearly 600 daily flights.

Neeleman, who will remain the airline's board chairman, is being replaced as chief executive by Dave Barger, who has been president.

The switch comes less than three months after two winter storms forced JetBlue to cancel nearly 1,700 flights. Neeleman acknowledged yesterday that it was time for him to step aside.

"I think the board has been talking about this for a long time," Neeleman said in an interview.

He had been chief executive since 1998. He said he would focus as chairman on strategic initiatives.

Still, some analysts said it would mark a significant change for a business whose brand became intertwined with Neeleman's personality.

"He has embodied the personalized service of that airline," said Richard Levick, president and chief executive of Levick Strategic Communications L.L.C., of Washington.

Pure energy, however, can carry a chief executive only so far.

"While Neeleman's infectious enthusiasm and entrepreneurial spirit [were] perfect for the company in its early start-up and hyper-growth phases, as the company matures, a renewed focus on operations will likely make JetBlue a stronger business," wrote William Greene, an analyst at Morgan Stanley, in a research note.

Neeleman conceded that his entrepreneurial skills did not translate well to the operational side of his business.

Storms on Valentine's Day and St. Patrick's Day essentially shut JetBlue down, forcing the cancellation of nearly 1,700 flights and stranding thousands of travelers throughout the Northeast.

The canceled flights and vouchers cost JetBlue $41 million, contributing to the company's first-quarter loss of $22 million, or 12 cents a share.

Neeleman characterized the change as "a natural evolution" of JetBlue's leadership structure rather than a direct result of the storms. The switch in leadership came at the request of the company's board, which wanted to separate the jobs of chief executive and chairman, he said.

Ray Neidl, an analyst at Calyon Securities Inc., said the change was not surprising. JetBlue has been consistently "rotating" new managers into the company in recent quarters, he said.

But one cannot ignore the impact the storms had on JetBlue, he said.

"That was probably the final straw" for Neeleman, Neidl said.